WO2024180428A1

WO2024180428A1 - Proportional volumetric dosing device

Info

Publication number: WO2024180428A1
Application number: PCT/IB2024/051664
Authority: WO
Inventors: Renato Brevini; Stefano Brevini
Original assignee: Mixtron S.R.L.
Priority date: 2023-03-02
Filing date: 2024-02-21
Publication date: 2024-09-06
Also published as: IT202300003831A1

Abstract

A proportional volumetric dosing device (1,1',1'') is described, comprising: a motor (20) provided with: an inlet conduit (10) of a first liquid and an outlet conduit (15) of a mixture of the first liquid with a second liquid, a tubular body (105) into which the inlet conduit flows, a piston (30) provided with a portion (65) slidably inserted in the tubular body (105) and movable along a respective sliding axis (X) between a top dead centre position and a bottom dead centre position, an output shaft (31) integral in sliding with the piston, and a base portion coaxial to the sliding axis (X). The dosing unit also comprises a pump (25,25') provided with: an inlet port of the second liquid, a pumping unit of the second liquid, said pumping unit being in fluid communication with the inlet port of the second liquid, being driven by the output shaft (31) of the motor and being provided with an outlet of the second pumped liquid, and a base portion coaxial to the sliding axis (X) and by means of which the pump is fixed to the motor. In addition, the dosing unit includes a by-pass conduit (600,605) connecting the outlet of the pumping unit to the outlet conduit (15) of the motor by-passing the inlet conduit (10) and an axial cavity (116) of the tubular body comprised between the piston and the inlet conduit. Where the by-pass conduit (600,605) includes at least a portion passing through an interface area between the motor and the pump at said bases.

Description

PROPORTIONAL VOLUMETRIC DOSING DEVICE

TECHNICAL FIELD OF THE INVENTION

The invention relates to a proportional volumetric dosing device, in particular of the type that is driven solely by the energy provided by the flow of a first liquid into which the dosing device must mix a predetermined amount of a second liquid.

PRIOR ART

As is well known, a proportional volumetric dosing device is a device that allows a first liquid to be mixed with a second liquid, for example containing an additive or an active ingredient, for a variety of applications in all those sectors where it is necessary to mix a first liquid with a second liquid or an additive in precise proportions. The first liquid may typically be water and the second liquid, may be an oil, fertiliser, detergent, chemicals or pharmaceuticals in solution or the like depending on the application sector of the dosing unit.

Said dosing units operate without the need to be connected to sources of electrical energy, but only due to the effect of the pressure and flow rate of the first liquid.

These dosing units have a hydraulic motor provided with a body inside which a piston is translated, slidably inserted in a cylinder of said body along a sliding axis, and driving a pump of the dosing unit itself, whose function is to suck the second liquid from a conduit or tank.

In a first type of dosing unit, the second liquid is fed directly into the motor body, while in a second type of dosing unit, the second liquid is fed into a by-pass conduit which leads from the pump into an outlet conduit of the motor, thus by-passing the motor.

The second type of dosing unit is generally used when the second liquid causes wear (is corrosive) on the internal components of the motor, such as the piston and its lip seals or gaskets.

The by-pass conduit is generally made as a tube, which extends from a through-hole in a wall of a pump sleeve, through which the pump is attached to the motor, to a through- hole in a tubular portion of the motor, which makes the motor outlet conduit available.

A problem with this solution lies in the fact that this tube constitutes an additional encumbrance in relation to the dosing unit and, in addition to being not very compact, is therefore exposed to impacts.

An object of the present invention is to overcome the aforementioned constraints of the prior art by means of the features of the independent claim, which outlines an economical, robust and efficient solution. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

DISCLOSURE OF THE INVENTION

The invention makes available a proportional volumetric dosing device comprising a motor provided with:

- an inlet conduit of a first liquid and an outlet conduit of a mixture of the first liquid with a second liquid,

- a tubular body into which the inlet conduit flows

- a piston provided with a portion slidably inserted into the tubular body and movable along a respective sliding axis between a top dead centre and a bottom dead centre position,

- an output shaft integral in sliding with the piston,

- a portion of the base coaxial to the sliding axis (and from which the tubular body extends).

The dosing unit according to the invention comprises a pump provided with:

- an inlet port for the second liquid,

- a pumping unit (assembly of elements, pumping unit, comprising valves and/or gaskets, acting in direct contact with the liquid in order to pump it) of the second liquid, said pumping unit being in fluid communication with the inlet port of the second liquid, being driven by the output shaft of the motor and being provided with an outlet of the second pumped liquid,

- a portion of the base coaxial to the sliding axis and through which the pump is fixed to the motor wherein the dosing unit comprises:

- a by-pass conduit connecting (only) the outlet of the pumping unit to the outlet conduit of the motor by-passing the inlet conduit and an axial cavity of the tubular body comprised between the piston and the inlet conduit, said dosing unit being characterised in that the by-pass conduit includes at least a portion passing through an interface area between the motor and the pump at said bases.

This solution provides a dosing unit with by-pass that is more compact than known dosing units with by-pass, as well as being safer, since the by-pass conduit is no longer protruding from the pump body and motor body and is therefore protected from impacts. In addition, the path inside the dosing unit, i.e. the pump and motor bodies, proposed by the present solution is shorter than the usual path of known external bypass conduits, which is advantageous in the case of low dosages, i.e. small quantities of the second pumped liquid, which would otherwise be more difficult to mix with the first liquid.

According to an embodiment of the invention, said portion of the by-pass conduit passes through a wall of the base portion of the pump and a wall of the base portion of the motor, also passing through an area of mutual contact between said walls.

In this case, another aspect of the invention may envisage the pump comprising a sleeve by means of which the pumping unit is fixed to the motor and which comprises an internal volume of the sleeve itself in direct fluid communication with the outlet of the pumping unit, wherein the by-pass conduit comprises an inlet port made in an inner surface of the sleeve, a first section extending from the inlet port to the interface area, and a second section made in the motor body extending from the interface area to the outlet conduit, at which there is an outlet port of the by-pass conduit itself.

In accordance with another embodiment of the invention, said portion of the by-pass conduit passes through a separating septum, in which the output shaft is fluidly sealed and which divides a pump volume downstream of the outlet of the pumping unit from said motor volume in communication with the inlet conduit and which is at least partially defined by the tubular body and the piston.

In such a case, an aspect of the invention may also envisage the by-pass conduit comprising an inlet port made in a face of the separator septum facing the outlet of the pumping unit, a first section extending from said inlet port towards the tubular body of the motor, and a second section passing through a wall of the tubular body in contact with the separator septum and having an outlet port made in an outer wall of the tubular body or in the outlet conduit.

According to yet another aspect of the invention, the pump may comprise a sleeve by means of which the pumping unit is fixed to the motor and which comprises the pump volume downstream of the pumping unit outlet, and in which said separating septum is accommodated in the tubular body of the motor or in the pump sleeve occluding one side thereof. Regardless of the exact configuration of the by-pass conduit, this by-pass conduit can be provided with an outlet port whose central axis is parallel (coaxial) to a longitudinal axis of the outlet conduit.

The mixing of the first liquid with the second liquid is improved therein.

In order to further improve mixing, another aspect of the invention envisage the by-pass conduit at its outlet comprising a nozzle with a narrower passage cross-section than the rest of the by-pass conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be more apparent after reading the following description provided by way of non-limiting example, with the aid of the accompanying drawings.

Figure 1 is a sectional view of a proportional volumetric dosing device according to the invention.

Figure 2 is a sectional view of a proportional volumetric dosing device according to another embodiment of the invention.

Figure 3 is an enlargement illustrating a detail A present in both the proportional volumetric dosing device of figure 1 and the dosing unit of figure 2.

Figure 4 is a partial section view of a further embodiment of the present invention.

Figure 5 is an enlargement of a motor of the dosing units of the previous figures.

BEST MODE TO IMPLEMENT THE INVENTION

With particular reference to said figures, 1 ,1 ’, 1 ” indicates a proportional (piston) volumetric dosing unit, which is adapted to mix a first liquid (main liquid) entering from an inlet port 11 of an inlet conduit 10 with a second liquid (auxiliary liquid) so as to provide at the outlet, in an outlet port 16 of an outlet conduit 15, a mixed liquid, which is formed by a predefined percentage of first liquid and a predefined percentage of second liquid established by the volumetric dosing unit itself.

The proportional volumetric dosing device 1 ,1 ’,1 ” has a (hydraulic) motor 20, driven by the flow of the first liquid through the motor itself, and a pump 25,25’ for dispensing the second liquid, which is fixed to the motor and driven by it in order to deliver said second liquid.

The motor 20 may comprise a motor body 35, e.g. of tubular shape, to which the pump is fixed and which comprises the inlet conduit 10 and the outlet conduit 15. For example, the inlet and outlet conduits may protrude from the tubular body.

The motor comprises a piston 30 slidably accommodated in the motor body along a sliding axis X and which is moved along said sliding axis by the force generated by the flow of first liquid between a top dead centre position (abbreviated hereafter as TDC and visible in the figures) and a bottom dead centre position (abbreviated hereafter as BDC and not shown in the figures).

The motor comprises an output shaft 31 , which is coaxial to the sliding axis X, i.e. it is coaxial to the sliding axis X and extends longitudinally along said sliding axis, is movably integral with the piston 30 between the bottom dead centre position and the top dead centre position (i.e., it is also movable between a top dead centre position and a bottom dead centre position), and has a first axial end (always) connected (directly) to the piston and an opposite second axial end (always) inserted into the pump 25,25’. In particular, the first axial end is fixed without residual degrees of freedom to the piston.

The motor body 35 can comprise a cylinder within which the piston 30 is slidably inserted (to size) along the sliding axis X. This cylinder thus has a central axis coaxial to the sliding axis X.

In addition, the motor housing 35, at an end opposite an end to which the pump is fixed, can be closed (at the top) by a cover (or cap) 40. In the top dead centre position the piston 30 is proximal to the lid and in the bottom dead centre position the piston 30 is distal from the lid.

With particular reference to figure 13, said piston 30 may include a top 55 (facing the lid), e.g. an upper top.

The piston 30 is, for example, a differential type piston, which therefore has a first cylindrical body 60, which is provided with the top 55, and a second cylindrical body 65 integral (without residual degrees of freedom) to the first cylindrical body sliding along the sliding axis X and which extends from a face of the first cylindrical body opposite the top 55.

In particular, the first cylindrical body 60 comprises a first major (circular) face transverse to the sliding axis X and which makes the top 55 available, an opposite second major face transverse to the sliding axis X and from which the second cylindrical body 65 rises, and a cylindrical lateral cylindrical outer surface 70 (coaxial to the sliding axis X).

The second cylindrical body extends, for example from the second face, coaxially to the first cylindrical body and in the direction away from the top 55 (towards the pump and in the direction away from the cap).

The second cylindrical body has a smaller diameter than the diameter of the first cylindrical body. In particular, the second cylindrical body comprises a cylindrical lateral outer surface 75 coaxial to that of the first cylindrical body (and extending from the face of the first cylindrical body opposite the top) having a smaller diameter than the cylindrical lateral outer surface 70. Thus, there is an annular surface opposite the top (being part of the second major face of the first cylindrical body), transverse to the sliding axis X and extending between an end of the cylindrical lateral outer surface 70 proximal to the second cylindrical body at an end of the cylindrical lateral outer surface 75 proximal to the first cylindrical body 60.

The second cylindrical body 65 is preferably axially hollow (along the sliding axis X), i.e. it is a cylindrical tubular body (thin-walled), and is provided with the cylindrical outer lateral surface 75 and an opposing tubular inner lateral surface defining an inner axial cavity in direct fluid communication with the inlet conduit 10, as will become clearer below. The cylindrical outer lateral surface 75 and the tubular inner lateral surface define an opening made at one end of the second cylindrical body 65 distal from the first cylindrical body and which is in free and direct fluid communication with the inner cavity of the second cylindrical body.

A portion of output shaft 31 proximal to the first axial end of the output shaft itself is contained in the inner axial cavity of the second cylindrical body.

The motor 20, i.e., the motor body 35, comprises a first (outer) tubular body 100 comprising a cylindrical inner surface 1 10 which accommodates to size (with reduced clearance) the first cylindrical body 60 of the piston, guiding it slidably along the sliding axis X, and a second (inner) tubular body 105 at least partially accommodated in the first tubular body 100 comprising a cylindrical inner surface 1 15 which accommodates to size (with reduced clearance) the second cylindrical body 65 of the piston, guiding it in slidably along the sliding axis X.

The first tubular body also comprises a tubular outer surface 1 11 opposite the inner cylindrical surface, which together with said cylindrical inner surface defines a thickness of the first tubular body 100.

The outlet conduit 15 comprises a radially more internal portion, with respect to the sliding axis X, relative to the outer tubular surface 1 1 1 , and a radially more internal portion, with respect to the sliding axis X, relative to the outer tubular surface 1 1 1. The radially more external portion substantially protrudes from a section of the outer tubular surface 1 1 1. The inlet conduit 10 also comprises a radially more internal portion relative to the tubular outer surface 1 1 1 , and a radially more external portion that substantially protrudes from the tubular outer surface 1 1 1.

The cap 40 is fixed to the first tubular body closing one end of the first tubular body distal from the pump.

At one end of the first tubular body opposite the cap, the first tubular body is joined to the second tubular body, e.g. at one end of the second tubular body proximal to the pump. The second tubular body 105, on the other hand, is spaced by a non-zero amount from the cap 40, such that it is not closed by the cap. In particular, the second tubular body 105 has a longitudinal extension along the sliding axis X that is smaller than a longitudinal extension of the first tubular body 100. In further detail, the second tubular body 105 has a greater minimum distance from the lid than the first tubular body (which, for example, directly contacts the lid).

The second tubular body 105 is internally coaxial to the first tubular body 100 with respect to the sliding axis X and is dimensioned so that there is an (annular) gap between the inner cylindrical surface 1 10 of the first cylinder 100 (i.e. a portion of this surface 110 radially aligned with the surface 120 with respect to the sliding axis X), and an outer (cylindrical) lateral surface 120 of the second tubular body itself. This cavity is in direct fluid communication with the outlet conduit 15, in particular the outlet conduit is derived directly from said cavity. Instead, the inlet conduit 10 is isolated from this cavity by a wall of the inlet conduit itself; more specifically, this conduit does not communicate directly with the cavity.

Further, the cylindrical inner surface 1 15 defines an axial cavity 1 16 in direct fluid communication with the inlet conduit 10, i.e. the inlet conduit makes an outlet port (opposite the inlet port 1 1 ) in the cylindrical inner surface 1 15 in direct fluid communication with the inlet port.

The second cylindrical body of the piston slides within the axial cavity 1 16 and, for example, between top dead centre and bottom dead centre, a portion of the second cylindrical body is always contained within the axial cavity 1 16.

The axial cavity 1 16 and the inner cavity of the second cylindrical body are therefore always in fluid communication with each other.

While the cylindrical inner surface 105 of the first tubular body 1 10 is crossed by the outlet conduit, the outlet conduit does not intersect the second tubular body, so it does not communicate directly with the axial cavity 116.

The axial cavity 116 and the internal axial cavity of the first cylindrical piston body are always in direct fluid communication with each other. Consequently, the internal axial cavity of the first cylindrical piston body is always in direct fluid communication with the inlet conduit 10.

The first tubular body 100, i.e. its inner surface 1 10, together with the lid 40 and the first cylindrical body 60 of the piston delimits (entirely) a first chamber 45 of the motor, while the first tubular body 100, i.e. its inner surface 110, together with the first cylindrical body 60, the second cylindrical body 65 i.e., its outer surface 75, and the second tubular body 105, i.e., its outer surface 120, delimits (entirely) a second (annular) chamber 50 of the motor, wherein said chambers are separated by the piston and can be put in communication with each other (and with the cavity 1 16) in a manner which will be described in detail below.

A volume of the gap between the first tubular body and the second tubular body is part of the second chamber 50 (in particular, when the piston is at bottom dead centre, the volume of the second chamber 50 corresponds to the volume of the gap).

The first chamber 45 is in indirect fluid communication with the inlet conduit (as will become clearer below by means of appropriate valves and mechanisms for actuating said valves) and the second chamber 50 is in direct fluid communication with the outlet conduit, in particular the gap is in direct fluid communication with the outlet conduit. In further detail, the outlet conduit has an inlet opening made in the cylindrical inner surface 110. When the piston is at top dead centre the volume of the first chamber 45 is minimum and the volume of the second chamber 50 is maximum, and at bottom dead centre position the volume of the first chamber is maximum and the volume of the second chamber is minimum.

The cavity 1 16, the face of the first cylindrical body from which the second cylindrical body rises, and the inner cavity of the second cylindrical body of the piston delimit (entirely) a third chamber, which is in direct fluid communication with the inlet conduit 10 and in indirect fluid communication with the first chamber (and thus with the second chamber). When the piston is at top dead centre the volume of the third chamber is maximum, whereas when it is in the bottom dead centre position the volume of the third chamber is minimum.

The piston 30 has the top 55, e.g. made available by the first cylindrical body (and facing the lid), and also has an annular sealing lip 80 which rises from the top of the piston (or from the cylindrical lateral outer surface 70 of the first cylindrical body 60, or from both), in particular, which rises from an outer annular perimeter edge of the piston top, and which insists in contact with the inner cylindrical surface 1 10 of the first tubular body, creating a fluidic seal between the surface 1 10 and the first cylindrical body (between the first chamber and the second chamber). If the annular sealing lip were not present, the fluid could flow laterally to the piston in the gap between the cylinder and the piston due to the coupling clearance between said two elements.

The annular sealing lip 80 is in contact with the cylinder at least along a continuous circumference, i.e. without interruption. Preferably it is in contact therewith along a continuous cylindrical surface.

The piston 30 may comprise a further annular sealing lip 125, substantially shaped in a similar manner to the annular sealing lip 80 which slides in contact with the inner cylindrical surface 1 15 of the second cylinder 105 so as to achieve a fluidic seal between the surface 1 15 and the second cylindrical body 65 (thus separating the axial cavity 1 16 and the inner axial cavity of the second cylindrical body, i.e. the third chamber, from the second chamber 50).

The volumetric dosing unit can comprise an elastic element which pushes the annular sealing lip 80, i.e. the (free) end portion of the annular sealing lip against the cylinder, i.e. the first cylinder 100, even more specifically against the inner cylindrical surface 1 10 of the first cylinder 100.

The axial cavity of the second cylinder 105, i.e. the third chamber, is in communication with the outlet conduit 15 via a valve system. In particular, the axial cavity of the second cylinder 105, i.e. the third chamber, is in communication with the first chamber (only) via at least one valve and the first chamber is in communication with the second chamber (only) via a second valve.

For a detailed description of this valve system, please refer to document US201916423366, which is incorporated herein for reference purposes. With particular reference to figure 5, the valve system comprises at least one internal valve 130 and one external valve 135, wherein the expression internal valve means a valve proximal to the sliding axis X along a radial direction and the expression external valve means a valve radially further away from the sliding axis X than the internal valve. The internal valve 130 is interposed between the axial cavity of the second cylindrical body 65 and the first chamber 45, i.e. between the third chamber and the first chamber, and for example, comprises a shutter 175 adapted to be engaged in a relative valve seat 180 made in the first cylindrical body 65, at a through hole (parallel and eccentric to the sliding axis X) which places the axial cavity of the second cylindrical body and the first chamber 45 in fluid communication.

The external valve 135, on the other hand, controls the opening and closing of a through- hole made in the first cylindrical body, which places the first chamber 45 in fluid communication with the second chamber 50. The external valve comprises a shutter adapted to be engaged in a valve seat made at this through-hole.

The valves are associated with a rocker 185 that is articulated, at one end, to the top of the piston so as to perform small oscillations, about an articulation pin thereof, alternatively between a first position, in which the internal valve 130 is closed and the external valve 135 is open, and a second position, in which the internal valve is open and the external valve is closed. In particular, the internal valve 130 is constrained to the rocker by a portion thereof, so that when the rocker rotates from the second to the first position, the portion of the internal valve 130 is moved upwards and causes the shutter to close the valve seat.

On the other hand, the shutter of the external valve 135 is directly supported by the rocker and, by rotating from the second to the first position, the rocker brings the shutter to a position distal from the valve seat, opening the corresponding external valve 135.

The movement of the rocker, which determines the respective opening and closing positions of the internal and external valves, is delegated to a spring activation mechanism. In the embodiment illustrated the spring activation mechanism is configured to be engaged in a slot 190, provided with a lower surface and an upper surface, e.g. opposite each other and aligned along a parallel direction to the sliding direction X, obtained in a body of the shutter 175 of the internal valve.

This elastic activation mechanism comprises a pair of connecting rods 195, where each connecting rod is associated with a respective spring 200.

Each connecting rod is fixed to a respective hinge 205 placed on the piston 30 and, through a hinge 210, which is housed in the slot 190, at a first end of the respective spring 200.

In turn the springs 200 are fixed in a second end thereof to a hinge 215 placed on a rod 220 slidably associated with the piston 30 i.e. that is constrained to the piston 30 so as to be able to translate with respect to the piston itself.

In particular, the rod 220 can slide vertically inside a through hole 26a obtained in the body of the piston 30 itself.

Furthermore, the rod 220 has a raised element constrained to slide within a guide 52 of the piston 30 that terminates at one end with a lower abutment element and at the opposite end with an upper abutment element, where said abutment elements can alternatively engage with the raised element of the rod to determine the respective stroke ends thereof along the translation axis of the rod, an axis which is parallel to the sliding axis X.

The position of the rod 220 in relation to the piston 30 determines the activation of the spring activation mechanism and regulates the upward and downward stroke of the piston.

As mentioned above, the motor and pump are fixed to each other, e.g. rigidly by means of removable connecting parts, e.g. threaded.

For example, they are fixed to each other at a (single) mutual interface area, at which the pump and motor are mechanically joined. This interface area is crossed by the output shaft 31 and is coaxial thereto.

In particular, the motor body has a base portion to which a base portion of the pump is fixed, wherein both said base portions are crossed by the output shaft 31 and are coaxial to the sliding axis X.

With particular reference to Figures 3-5, the base portion of the motor body comprises an interface face (surface) 1 18 (transverse to the sliding axis X) which is directly facing, e.g. also (partially) in contact, on the base portion of the pump, i.e. on an interface face (surface) 119 of the base portion of the pump facing the motor.

The interface area comprises the interface face 1 18 and interface face 1 19, which are, for example, made at least partially available by the respective base portions and are radially delimited in their distance from the axis X by the respective base portions. The base portion of the motor body comprises a wall, transverse (perpendicular) to the sliding axis X, which comprises a (single) through-hole that crosses the interface face 118, which is crossed by the output shaft (and which would communicate with the axial cavity 1 16). Around the through-hole there is an annular surface at which the pump is fixed. This annular surface can be considered as an end of the second tubular body of the motor distal from the lid 40.

This through-hole may be sized around the output shaft 31 , i.e., in which the output shaft 31 slides in with little clearance and there is a fluidic seal in the through-hole that insists on the output shaft, or, as in the illustrated embodiment, the through-hole is sized such that the output shaft 31 is slidably accommodated therein with ample clearance such that fluid communication between the motor, i.e., the cavity 1 16, and the pump would be permitted. Such communication is prevented by a plug 230 (non-permeable, i.e., impermeable), i.e., a separating septum 230, which partially sealingly occludes the through-hole section passing through the interface face 1 18 and which is in turn provided with a single through-hole (the only possible communication passage between the motor i.e., the cavity 116, and the pump when the plug is in place) into which the output shaft 31 slides to size, which through-hole comprises a housing for a fluidic (dynamic) annular gasket 231 that is sealed against the output shaft 31 embracing it.

Between the through-hole of the base portion and the plug 230 there is an fluidic sealing (static) annular gasket 232, which prevents the passage of fluid from the axial cavity 1 16 between the plug and the hole in which the plug is inserted.

In addition, there may also be an additional fluidic sealing (static) annular gasket 233 placed in contact between the plug, the through-hole in which the plug is inserted, and the pump sleeve, as will become clearer below, so as to achieve a fluidic seal between these elements.

The gasket 232 and the gasket 233 are spaced from each other along the sliding axis X by a non-zero amount, in particular the gasket 232 is closer to the piston and the gasket 232 is closer to the pump.

In the embodiment shown, this plug 230 is fixed, e.g. removably, to the motor, i.e. to the through-hole. In particular, the plug 230 comprises a first portion proximal to the piston and a second portion distal from the piston and which is fixed (screwed) to the first portion by clamping between said first and second portions a step in the through-hole of the base portion, e.g. made within the step itself.

Regardless of the exact embodiment of the cap, it is to be considered part of the base portion of the motor and, for example, makes available part of the interface face 1 18 of the motor, in particular together with an annular surface of the motor body surrounding the cap, which is made available by the wall of the base portion of the motor.

From said base portion of the motor body, i.e. from the wall of said portion in which the through-hole is present, second tubular body rises (in the direction away from the pump) and, for example, the inlet and outlet conduits also extend therefrom. In particular, the second tubular body rises from a radially more external section to the through-hole (with respect to the sliding axis X).

The figures illustrate two embodiments for a pump adapted to be driven by the motor 20, in particular by the movement of the output shaft 31 in its motion between the BDC and TDC, of which one pump 25 and one pump 25’, which differ in their operating principle, in particular in the pump 25 the second end of the output shaft 31 is free, whereas in the embodiment 25’ a piston is rigidly fixed to the second end of the output shaft.

The pump 25 comprises a pumping unit of the second liquid which is in fluid communication with an inlet port 315 of the second liquid and has an outlet of the second pumped liquid.

It is specified that a pumping unit is an assembly of elements comprising valves and/or gaskets, which acts in direct contact with the liquid to pump it and direct it towards the outlet of the second liquid of the pump itself.

The pumping unit of the pump 25 comprises a tubular body 300 coaxial to the output shaft 31 and which comprises a (cylindrical) inner tubular surface 305 coaxial to the output shaft 31 . A portion of the output shaft starting at the second end of the output shaft itself, when said output shaft is at (near) the BDC, is accommodated entirely in an internal volume of the tubular body defined (partially) by the inner tubular surface 305.

This internal volume together with the output shaft 31 at least partially defines a pumping chamber, and in its motion between TDC and the BDC, the output shaft variably occupies the internal volume of the tubular body 300, thus varying the extension (value/size) of the pumping chamber. Specifically, when the output shaft 31 is at the BDC the pumping chamber has a minimum extension and when the output shaft 31 is at the TDC the pumping chamber has a maximum extension. The inner tubular surface 305 preferably has a passage cross-section such that the output shaft 31 is inserted into it with little clearance and, when inserted, there is a non-zero sized gap between the lateral surface of the output shaft itself and the inner tubular surface 305, into which the second liquid can flow.

The tubular body 300 comprises a first longitudinal end, distal from the motor, at or near which the inner tubular surface 305 makes available an inlet port 315 of the second liquid to be pumped, and an opposite second longitudinal end, proximal to the motor, and at or near which the inner tubular surface makes available an outlet port 320 of the second liquid.

The tubular body may comprise a (cylindrical) outer tubular surface opposed to the inner tubular surface, e.g. coaxial to the sliding axis X, which is a non-zero distance from the surface 305 defining a (non-zero) thickness of the tubular body itself.

The pump 25 then comprises a sleeve 330 (tubular and rigid) coaxial to the output shaft 31 , i.e. the sliding axis X, which connects the pumping unit, in particular the tubular body 300, to the motor, i.e. the motor body 35. For example, the sleeve 330 comprises a portion thereof fixed by means of threaded connection members to the motor, i.e. the motor body 35. In particular, the sleeve is fixed to the motor body 35 on a side opposite the lid 40, e.g. by contacting the annular surface around the plug 230.

Therefore, it is the sleeve 330 that makes the base portion of the pump 25 available, and also the interface face 1 19. In detail, the basic portion of the pump comprises (i.e. consists of) the end of the sleeve 330 in contact with the motor, i.e. the motor body, and it is substantially an annular wall (coaxial to the sliding axis X). The sleeve therefore also makes available an annular surface in contact with the motor, i.e. with the respective annular surface of the base portion of the motor, which is a portion of said annular wall in contact with the motor and forms part of the interface face 1 19.

The sleeve 330 comprises an internal volume 335, within the sleeve 330 itself, in fluid communication with the outlet of the pumping unit, in particular with the outlet port 320 of the second fluid, i.e. with the internal volume of the tubular body 300, i.e. with the pumping chamber of the pumping unit.

This internal volume 335 partially accommodates the tubular body 300. Specifically, the sleeve comprises a (cylindrical) inner tubular surface 340 that delimits the internal volume 335. The sleeve 335 also has an outer tubular surface 345, which together with the inner tubular surface defines a thickness of the sleeve itself.

The internal volume 335 is fluidically isolated from the inner cavity 1 16, in particular either by means of the interface face, the output shaft and the gasket that insists on the output shaft and that is housed in the through-hole, or, as in the illustrated embodiment, by means of the plug 230, the output shaft and the gasket that insists on the output shaft and that is housed in the plug 230.

The internal volume 335 is also delimited at one end by the tubular body 300 and at an opposite end by the motor body, i.e. by the interface face 1 18, for example by a face of the plug 230 facing the pumping unit.

In particular, the motor, i.e. the interface face 1 18 (the face of the plug 230 facing the pumping unit) together with the output shaft 31 (and the gaskets insisting on the output shaft) close off one side of the internal volume distal from the pumping unit, thereby preventing fluid communication between the internal volume and the axial cavity 1 16.

The sleeve is substantially shaped like a tubular body at one end fixed to the motor at an opposite end and its inner tubular surface has a diameter at least greater than the diameter of the outer tubular surface 325 of the tubular body 300.

The pumping unit comprises an elastic annular sealing gasket 350 crossed by the output shaft, i.e. by a section of the output shaft 31 , in its motion between the BDC and the TDC, which makes a fluidic (hermetic) seal on the output shaft 31 , and which together with the output shaft 31 , when the latter passes through the annular gasket itself, is adapted to occlude the outlet port 320.

Said section of the output shaft extends between a point on the output shaft in contact with the gasket 350, when the shaft is at the BDC, and a point proximal to the second end contacting the gasket 350 when it is at the TDC or the second end itself of the output shaft in the case where at the TDC the output shaft is external to the tubular body 300 and not inserted in the annular sealing gasket.

In particular, said section of the output shaft may comprise all or part of the portion of the output shaft contained within the internal volume of the tubular body 300 when said shaft is at BDC.

The annular sealing gasket 350 comprises an inner (tubular) annular surface (essentially defining a through-hole coaxial to the sliding axis X) into which said section of the output shaft is sealingly inserted to size (in other words, the inner annular surface sealingly embraces the section of the output shaft running through it).

When the annular sealing ring 350 occludes the outlet port 320 together with the output shaft, the second liquid present in the internal volume, i.e. in the pumping chamber, can push on an annular surface of the annular sealing gasket 350 around the inner annular surface and which extends from said inner annular surface.

The annular sealing gasket 350 comprises an outer (tubular) annular surface, e.g. cylindrical, opposite the inner annular surface and preferably coaxial to the sliding axis X.

The annular sealing gasket 350 further comprises a first flat face perpendicular to the sliding axis X, which connects the inner annular surface to the outer annular surface, and a second flat face perpendicular to the sliding axis X, opposite the first face, which connects the inner annular surface and the outer annular surface on one side of these opposite surfaces to the first face.

The first face provides the annular surface of the annular sealing gasket 350, which is located (externally) around the inner annular surface and has a smaller diameter than the diameter of the inner tubular surface 305 at the outlet port 320.

The annular sealing gasket 350 illustrated is, for example, a cylindrical body, preferably disc-shaped, in which a through-hole defining the inner annular surface 355 is made.

In the embodiment of the annular seal 350 illustrated, it comprises a plurality of (equal) protrusions, e.g. three in number, extending radially from the outer annular surface in the direction away from it.

Two protrusions adjacent to each other essentially form a groove (radial to the sliding axis X) in the annular sealing gasket corresponding to the outer annular surface of the annular sealing gasket, which groove extends parallel to the sliding axis and is designed to bring into fluid communication an environment over which the first face of the annular sealing gasket faces with an environment over which the second face of the annular sealing gasket faces. The plurality of protrusions thus forms a plurality of grooves in the annular seal at the outer annular surface of the annular seal, which extend parallel to the sliding axis and are designed to place in fluid communication an environment over which the first face of the annular sealing gasket faces with an environment over which the second face of the annular sealing gasket faces.

The tubular body 300 includes a housing seat for the annular sealing gasket 350 (coaxial to the sliding axis X) made at or near the second end in the tubular body 300 and at the outlet port 320 of the second liquid. The housing is in fluid communication (direct and always) with the internal volume 335 of the sleeve and is crossed by said section of the output shaft 31.

In the embodiment illustrated, the housing seat comprises a (flat) abutment surface that is derived from the inner tubular surface 305 of the tubular body 300 in the direction away from the sliding axis X and transverse (perpendicular) thereto, e.g. this abutment surface is annular, preferably shaped like a circular crown.

The housing also comprises a lateral surface (tubular, e.g. cylindrical), which is coaxial to the sliding axis X and extends from the abutment surface, e.g. parallel to the sliding axis X, preferably close to the motor.

The housing seat, i.e. its lateral surface, creates in the second end of the tubular body 300 an access port (crossed by said section of the output shaft) to the outlet port 320 and which is in fluid communication with the internal volume of the sleeve.

The housing and the annular seal must be shaped in such a way that an airtight seal is achieved along at least one closed circular loop surface when the annular sealing gasket is accommodated in the housing seat. For example, a hermetic seal is achieved by an annular portion, e.g. contiguous to the annular portion on which the second liquid pushes, of the first face of the annular sealing gasket when said first face is in contact with the abutment surface.

When the annular sealing gasket is not tightly sealingly housed in the housing seat, i.e. its sealing portions do not contact the housing seat and are spaced apart from it, the grooves and/or a (radial) clearance present between the outer annular surface of the annular sealing gasket and the lateral surface allow a fluidic connection between the internal volume of the tubular body, i.e. the pumping chamber, and the internal volume of the sleeve (in particular with the access opening made in the second end of the tubular body from the housing seat).

At an opposite end to the housing seat of the annular sealing gasket 350, the pumping unit may comprise a one-way valve 395 which governs the passage of the second liquid through the inlet 315 allowing only flow into the internal volume, i.e. into the pumping chamber, and not out of it.

For example, the tubular body 300 includes a housing for such a one-way valve 395, which is made at the first end and in fluid communication with the inlet port 315. Preferably, the pump also includes a plug 400 that can be removably fixed to the tubular body 300, e.g. the plug comprising a threaded surface for screwing onto a threaded surface of the tubular body 300, which holds the one-way valve 395 in the respective seat. This plug 400 includes a through-hole in fluid communication with the pumping chamber when the one-way valve 395 is open.

The inner tubular surface 305, together with the annular sealing gasket 350, the one-way valve 395 and the output shaft 31 (and the housing seats for the annular sealing gasket and the one-way valve respectively) define the volume of the pumping chamber.

The pumping unit comprises a thrust device, e.g. a spring 405, which generates a thrust on the annular sealing gasket 350, in particular by acting on the second face, in a direction that keeps the annular sealing gasket in contact with the housing seat, thus creating a hermetic seal with it.

The thrust device preferably generates a thrust on the annular sealing gasket, such that the annular sealing gasket is held in the housing seat and a hermetic seal is generated, when the output shaft 31 moves from BDC to TDC.

The thrust generated by the thrust device must then not be excessive, since when the output shaft 31 moves from top dead centre to bottom dead centre and is inserted into the inner annular surface of the annular sealing gasket, the force of the thrust device, i.e. the spring, must be able to be overcome by the second liquid.

As a result of the action of the thrust device on the annular sealing gasket, the movement of the piston and the incompressibility of the liquid, the annular sealing gasket 350 is movable, according to a balance (difference) of forces acting on it between a closed position, in which it makes a hermetic seal with the housing seat and the internal volume of the tubular body 300 i.e. the pumping chamber, is isolated from the internal volume 335 of the sleeve, and an open position, in which the annular sealing gasket is at least partially spaced from the housing and the internal volume of the tubular body, i.e. the volume of the pumping chamber, is in communication with the internal volume 335 of the sleeve.

In order to reduce the stagnation of the second liquid in the vicinity of the outlet port 320, an anti-stagnation conduit 410 is located at the second axial end of the tubular body (on one side of the housing seat opposite the abutment surface), which is coaxial to the sliding axis X, and which is crossed by the output shaft, extending in the direction towards the motor. This conduit 410 has a smaller diameter than the housing seat of the annular sealing gasket, in particular smaller than the lateral surface 385.

The anti-stagnation conduit comprises an inlet port, proximal to outlet port 320 and distal from the motor, and an opposite outlet port, distal from the outlet port 320 and proximal to the motor.

The anti-stagnation conduit 410 creates the outlet of the pumping unit in the embodiment shown. However, in a non-illustrated embodiment in which such a conduit 410 is not provided, the outlet of the pumping unit is formed by the outlet 320.

The pumping unit may comprise a retaining body 420 adapted to hold the pre-compressed thrust device spring in place and rigidly associated with the tubular body 300. In the illustrated case of the spring, it thus comprises a first longitudinal end in contact with the retaining body and a second longitudinal end in contact with the annular sealing gasket, in particular of the second face of the annular sealing gasket.

In both cases, the retaining body 420 partially closes the opening that the housing seat of the annular sealing gasket makes in the second end of the tubular body 300. The retaining body 420 can therefore also be considered as a plug equipped with the through- hole and partially closing said housing seat.

The retaining body 420 has a through-hole crossed by the output shaft 31 . For example, a volume of the housing seat of the annular sealing gasket 350 is in fluid communication with the internal volume of the sleeve via said through-hole of the retaining body. In particular, the through-hole of the retaining body is essentially the only route by which the second pumped liquid can move away from the housing seat. In the embodiment illustrated, the volume of the housing seat of the annular sealing gasket 350 is in fluid communication with the internal volume of the sleeve via said through-hole of the retaining body and the anti-stagnation conduit 410.

The tubular body 300 is inserted into the containment tubular body 420, and is retained inside it by means of the plug 400, which in this case is screwed into the containment tubular body 420 by squeezing the tubular body between the plug and a bottom wall of the containment tubular body opposite the plug 400.

In particular, the tubular containment body 425 comprises a first longitudinal end distal from the motor, which has an opening into which the tubular body 300 can be inserted (to size), and an opposite second longitudinal end, proximal to the motor and housed inside the internal volume of the sleeve, which has a bottom wall on which the second end of the tubular body 300 or the restraining body abuts.

The tubular body 300 is then clamped between the bottom wall and the plug 400.

The bottom wall is perforated to allow for the passage of the output shaft 31 , and the antistagnation conduit 410 is made available by the tubular containment body 425 and extends from the bottom wall.

The tubular containment body 425 comprises an inner tubular surface, into which the outer tubular surface of the tubular body 300 is inserted, and an opposite outer tubular surface, which extend from the bottom wall to the first longitudinal end of the tubular containment body itself.

Between the inner tubular surface of the tubular containment body 425 and the outer tubular surface of the tubular body 300, an annular sealing gasket is preferably interposed, e.g. positioned in a section comprised between the non-return valve and the second end of the tubular body 300.

The tubular body 300 may be movably associated with the motor, i.e., the sleeve 330, sliding along the sliding axis X, and for example, the pump 25 may comprise a mechanism for varying the position of the tubular body 300, configured to allow the sliding of the tubular body 300 along the sliding axis with respect to the sleeve 330 and the positioning, i.e. (stable) locking, of the tubular body 300 in a plurality of positions along the sliding axis X.

Since moving the tubular body 300 varies the point of the output shaft at said outlet port, the size of said section between the outlet port and the free end also varies, so the volume of second liquid pumped through the outlet port varies.

The stroke of the output shaft between BDC and TDC does not vary, i.e. it is constant. In other words, the distance of the free end in relation to a reference point taken on the motor (measured in a direction parallel to the sliding axis X), when the output shaft is at BDC, is always the same.

The position variation mechanism comprises a ring nut mechanism having a ring nut 430 rotatably associated with the sleeve and coaxial to the sliding axis X. In particular, said ring nut 430 is provided with a single residual degree of freedom in rotation about the sliding axis and is provided with an internal thread 435 which engages with an external thread 440 integral (without residual degrees of freedom) with the tubular body. In this way, a rotation of the ring nut 430 corresponds to a translation of the tubular body along the sliding axis.

Such an external thread 440 could be made on the outer tubular surface of the tubular body 330, however, it is preferably made in the tubular containment body.

The body 425 comprises an (annular) step made in one of its inner tubular surfaces and facing the motor, which goes into an (annular) step facing the first end of the tubular body 300 and the plug 400 clamps the further tubular body between itself and the step of the tubular body 300, thus making the tubular body integral with the further tubular body.

Returning to the ring nut, it has an enlarged end 450 (radially enlarged) which is housed in a conjugate annular groove formed in an enlarged portion of the sleeve 330 at the end of the sleeve distal from the motor.

This end of the sleeve 330 is then associated with a closing lid 455 configured to hold the enlarged end of the ring nut 430 in the annular groove.

Thanks to this configuration, the ring nut is associated with the sleeve with only one residual degree of freedom in rotation about the sliding axis X.

The sleeve 330 may comprise a locking system configured to selectively mechanically lock the tubular body 300, i.e. the additional tubular body, in a reached position, relative to the sleeve 330.

For example, the locking system is configured to mechanically lock by making a shape constraint, i.e. by making an obstacle connection.

Preferably, the shape constraint, i.e. the obstacle connection, which blocks the relative movement between the tubular body 300, i.e. the additional tubular body, and the sleeve is made by acting radially on an outer surface of the ring nut, in particular its enlarged portion.

This locking system comprises a lever, which is housed in a seat at the enlarged portion of the sleeve and which is constrained to the seat of the sleeve by an articulation hinge with an axis parallel to the sliding axis of the output shaft.

The lever has, at one end, a portion provided with reliefs and/or grooves, e.g. provided with a notching, adapted to engage with an outer portion of the ring nut 430 provided with reliefs and/or grooves configured to create a shape constraint with the reliefs and/or grooves of the portion.

Figure 2 shows the second embodiment of the pump, indicated as 25’, which comprises a pumping unit of the second liquid that is in fluid communication with an inlet port 315’ of the second liquid and has an outlet of the second pumped liquid.

The pump 25’ includes a sleeve 330 (tubular and rigid) coaxial to the output shaft 31 , i.e. to the sliding axis X, which connects the pumping unit, to the motor, i.e. to the motor body 35. For example, the sleeve 330 comprises a portion thereof fixed by means of threaded connection members to the motor, i.e. the motor body 35. Specifically, the sleeve is fixed to the motor body 35 on an opposite side to the lid 40.

Therefore, it is the sleeve 330 that makes the base portion of the 25’ pump available, and also the interface face 1 19. In detail, the basic portion of the pump comprises (i.e. consists of) the end of sleeve 330 in contact with the motor, i.e. the motor body, and it is substantially an annular wall. The sleeve therefore also makes available an annular face in contact with the motor, i.e. with the base portion of the motor, which is a portion of said annular wall in contact with the motor and forms part of the interface face 1 19.

The sleeve 330 includes an internal volume 335, inside the sleeve 330 itself, in fluid communication with the outlet of the pumping unit.

Specifically, the sleeve comprises a (cylindrical) inner tubular surface 340 that delimits the internal volume 335.

The sleeve 335 also has an outer tubular surface 345, which together with the inner tubular surface defines a thickness of the sleeve itself.

The internal volume 335 is also delimited at one end by the motor body, i.e. interface face 1 18, e.g. by a face of plug 230 facing the pumping unit.

The sleeve is basically shaped like a tubular body, with one end fixed to the motor at an opposite end distal from the motor. Inside the sleeve 330 the pumping unit is received, which includes a cylinder 585, for example, which has a threaded outer portion 850. The cylinder 85 has, in proximity to an upper end, a housing seat of an annular sealing gasket configured to prevent the passage of fluid between the tubular sleeve 330 and the cylinder 85.

At the distal end from the motor body 20, the cylinder 585 has a receiving seat of a oneway valve 590, located at a second liquid inlet port, which allows the second liquid to enter the cylinder 585 but prevents it from leaving.

A small piston 562 of the pump 25’ slides inside the cylinder 585, mechanically connected and rigidly connected to the output shaft in such a way that the stroke of the piston 562 is the same as that of the motor piston.

The internal volume of the cylinder 585, together with the small piston 562 partially define a pumping chamber 112 of the secondary fluid. In particular, the volume of the pumping chamber 1 12 is defined by the small piston 562, the cylinder 585 and the valve 590.

The small piston 562 comprises a plurality of openings 562a, arranged radially with respect to the sliding axis of the small piston 562 itself, for the outflow of the second liquid contained within the pumping chamber towards the internal volume 335 of the sleeve. A valve is associated with said openings 562a which allows the passage of the auxiliary fluid through them. In the embodiment illustrated, said valve comprises a friction gasket 564, housed in an annular groove of the small piston 562. The friction gasket 564, during the descent of the small doser piston 562, by rubbing along the inner surface of the cylinder 585 reaches a position in which it enables the outflow of the auxiliary fluid, previously sucked, through the channels 562a, whereas during the ascent of the small doser piston 562, by rubbing along the inner surface of the cylinder 585, the gasket 564 reaches a position in which it prevents the passage of the auxiliary fluid through the channels 562a, producing at the same time a depression in the pumping chamber 1 12.

The ascent and descent movement of the small doser piston 562 therefore allows the auxiliary fluid to be sucked into the pumping chamber and to be supplied to the internal volume 335.

On the threaded portion 850 of the cylinder 585 an outer ring nut 570 is screwed, which has an enlarged end that is housed in a conjugated annular hollow obtained in an enlarged end portion of the tubular sleeve 330.

A closing lid 810 is associated with the lower end of the tubular sleeve 330, such lid being configured to keep the enlarged end of the ring nut 570 in the annular hollow obtained in an enlarged end portion of the tubular sleeve 330.

Thanks to this configuration, and for example at a pair of tongues, the rotation of the ring nut 570 causes the axial translation of the cylinder 585, in this way varying the volume of the pumping chamber 1 12 and therefore the quantity of second liquid contained therein. As mentioned, by acting on the ring nut 750 it is possible to regulate the axial position of the cylinder 585 with respect to the tubular sleeve 330 and therefore to determine the volume of the pumping chamber for dosing the second liquid to be mixed.

The pump comprises a locking system 500 configured to mechanically lock the cylinder 585 against the sleeve 330.

For example, the locking system 500 is configured to mechanically lock the cylinder with respect to the tubular sleeve 330 by creating a shape constraint, i.e. by creating an obstruction connection.

The lever has, at one end, a portion provided with reliefs and/or grooves, e.g. provided with a notching, adapted to engage with an outer portion of the ring nut provided with reliefs and/or grooves configured to create a shape constraint with the reliefs and/or grooves of the portion.

Regardless of the exact pump embodiment, the basic portions of the motor and pump are joined to each other and in particular the annular surface coaxial to the axis X around the through-hole of the motor is contacted by a corresponding annular surface coaxial to the axis X of the sleeve 330 and defining an end of the sleeve proximal to the motor.

At least one between the motor and the pump comprises a wall, in the illustrated embodiment in the form of a separating septum or plug 230, which is crossed by the output shaft 31 and which divides the axial cavity 116 from the outlet of the pumping unit, in particular this wall creates a fluidic barrier between the internal volume 335 of the sleeve and the axial cavity 1 16. This wall closes the above-mentioned end of the sleeve 330 or the through-hole of the motor. Preferably, this partition wall includes the plug 230, i.e. is made of it, and closes the through-hole of the motor.

If there were no wall, i.e. if there were no plug 230 (and the seal on the output shaft), the sleeve 330 and the second tubular body of the motor would substantially make a single tubular body that would put the motor inlet conduit and the pumping unit outlet in direct fluid communication.

In particular, the only means of direct communication between these two volumes is the through-hole at the interface area between the pump and the motor in which the output shaft 31 slides sealingly, which through-hole is occluded by the output shaft and by the gasket 231 housed in said through-hole and which insists on the output shaft, creating a fluidic seal adapted to prevent fluidic communication between said volumes.

More specifically, the inner volume 335 of the sleeve and the axial cavity 1 16 are fluidi- cally separated by the plug 230, together with the shaft passing through the through-hole of the plug and the gasket 231 housed in that through-hole of the plug and insisting on the output shaft.

In the embodiment illustrated, the plug 230 is contained in the motor, but there is nothing to prevent it from being positioned inside the pump, i.e. inside the sleeve 330.

In this pump and motor configuration, wherein the outlet of the pumping unit 25,25, is isolated from the axial cavity 1 16 and from the inlet conduit, the volumetric dosing unit comprises a by-pass conduit 600,605 connecting (only) the outlet of the pumping unit i.e. the internal volume 335 of the sleeve 330, to the outlet conduit 15 of the motor (and/or to the cavity between the first tubular body and the second tubular body of the motor), bypassing the inlet conduit 10 and the axial cavity 1 16 of the second tubular body (i.e. the third chamber).

Consequently, the second liquid pumped by the pump 25,25’ does not enter the engine upstream of the piston 30.

Unlike dosing units of the prior art, the by-pass conduit 600,605 according to the invention does not protrude externally from the pump body and motor body, in particular, it does not protrude externally from the sleeve 330, i.e., it does not protrude externally from the outer lateral surface 340 of the sleeve, and it does not protrude externally from the portion of the motor which makes the outlet conduit 15 available (in further detail, it does not protrude radially, with respect to the sliding axis X, from the outer tubular surface 1 1 1 ). Additionally, the by-pass conduit 600,605 does not intersect the portion of the outlet conduit 15 that protrudes externally from the outer tubular surface 11 1 ).

In particular, the 600,605 by-pass conduit is (entirely) contained inside the motor and pump, i.e. inside the motor body and the pump body. As a further detail, a middle section of this conduit must also be inside either the motor or the pump, i.e. it must not protrude from the above-mentioned dosing unit elements.

The by-pass conduit 600,605 includes at least a portion, i.e. a section crossed by the second liquid, which passes through (only) the interface area between the motor and the pump at the pump and motor bases.

In further detail, this portion crosses the interface face 118 and the interface face 1 19. In other words, the by-pass conduit goes from the pump to the motor by crossing an imaginary plane at which the pump and motor are joined, and only crosses said plane at the respective bases (within them) of the motor and pump, i.e. it only crosses said plane at the interface face 1 18 and the interface face 1 19.

In a first embodiment of the by-pass conduit, denoted by reference number 600, the portion of the by-pass conduit that passes through the interface area, i.e. the entire by-pass conduit, crosses a separating septum (provided with a through-hole) in which the output shaft is sealingly housed and which divides a pump volume downstream of the pumping unit outlet from the motor volume that is at least partially defined by the tubular body and piston.

In detail, this separating septum is either the wall of the portion of the motor base or the sleeve that divides the axial cavity 1 16 from the internal volume 335 or, as in figures 1 -3, this separating septum is the plug 230, in which, for example, the by-pass conduit 600 has its first section.

The by-pass conduit 600 comprises an inlet port 610 made in the face of the plug facing the pumping unit (thus the face partially delimiting the internal volume 335) and an outlet port 615 which can be made either in the outlet conduit 15, i.e. in a tubular surface delimiting the outlet conduit 15, or preferably in the cavity between the first and second tubular body (thus flowing into the second chamber). For example, said outlet port 615 is made in the outer lateral surface 120 of the second tubular body 105 of the motor.

For example, there are a plurality of inlet ports 610 made on the face of the plug facing the pumping unit, which are joined together by an annular section of the by-pass conduit made inside plug 230.

A first section of the by-pass conduit, for example comprising the above-mentioned annular section, extends from the inlet port 610, which first section from the inlet port 610 propagates at least in part transversely to the sliding axis X in a direction away from said axis, through a lateral surface of the plug 230 coaxial to the sliding axis and contacting the through-hole, i.e. a lateral surface coaxial to the sliding axis X of the through-hole, of the motor base in which the plug 230 is inserted.

In further detail, the first section traverses a portion of this lateral surface of the plug 230 that is axially interposed (with respect to the sliding axis X) between the gasket 232 and the gasket 233 (without intersecting said gaskets or their respective housing seats).

The by-pass conduit does not pass through a face of the plug facing the piston (the lateral surface of the plug propagates from the face facing the pumping unit to the face facing the piston, e.g. the plug 230 may be substantially disc-shaped).

A second section, directly consecutive to the first, crosses the base portion of the motor where the through-hole in which the plug 230 is inserted is made and flows into the outlet conduit. In particular, the second section extends from the lateral surface of the through- hole to the surface 120.

The second section is essentially a terminal section of the by-pass conduit and, for example, this second section has a longitudinal axis, at least in the vicinity of the outlet port 615, which is parallel to a longitudinal axis along which the outlet conduit 15 extends. Preferably the second section is coaxial to the outlet conduit 15.

In addition, the outlet port is oriented so that the second liquid flows in the same direction along which the first liquid crosses the outlet conduit.

Additionally, there may be a nozzle 620 at the outlet port 615 which has a restricted cross- sectional area compared to the rest of the by-pass conduit, i.e. which has a restricted cross-sectional area at least compared to the second section of the by-pass conduit.

Such a nozzle is, for example, removably fixed (screwed) into the outlet port 615.

In a second embodiment of the by-pass conduit, indicated by reference numeral 605, the portion of the by-pass conduit passing through the interface area, i.e. the entire by-pass conduit, does not pass through the separator septum as in the first embodiment, but rather, passes through the wall of the base portion of the pump, i.e., the portion of the sleeve 330 in contact with the motor, and through the wall of the base portion of the motor, i.e., the portion of the motor in contact with the pump around the through-hole, e.g., in which the plug 230 is housed.

The by-pass conduit 600 comprises an inlet port 630 made in the sleeve 330, i.e. in the inner tubular surface 340, and an outlet port 635 which can be made either in the outlet conduit 15, i.e. in a tubular surface delimiting the outlet conduit 15, or preferably in the cavity between the first and second tubular body. For example, said outlet port 635 is made in the outer lateral surface 120 of the second tubular body 105 of the motor.

A first section of the by-pass conduit extends from the inlet port 630, which inlet port 630 propagates through the sleeve 330 between the inner tubular surface 340 and the outer tubular surface 345 (without crossing them) towards the motor.

At the interface face 1 19, the first section makes an opening. In particular, this opening is in the portion of sleeve 330 in contact with the motor, i.e. it makes an opening in the annular face of the sleeve in contact with the motor.

The by-pass conduit 605 then comprises a second section which (directly) from the first section, i.e. from the opening of said first section, extends inside the base of the motor, in particular inside the wall which makes the through-hole available, e.g. the through-hole in which the plug 230 is inserted, to the outlet port 635, made in the surface 120.

The second section makes an opening in the annular surface around the through-hole, i.e. around the plug 230, where this opening is directly communicating and contiguous to the opening of the first section.

The second section is essentially a terminal section of the by-pass conduit and, for example, this second section has a longitudinal axis, at least in the vicinity of the outlet port 630, which is parallel to a longitudinal axis along which the outlet conduit 15 extends. Preferably the second section is coaxial to the outlet conduit 15.

Regardless of the exact embodiments, in both cases the by-pass conduit 600,605 comprises an initial section in direct fluid communication with the internal volume 335 and a final section intersecting the gap between the first and second tubular body or the outlet conduit, in particular intersecting the radially more internal portion of the outlet conduit 15 with respect to the outer tubular surface 11 1 or the surface 120.

The operation of the proportional volumetric dosing device 10 takes place according to the following methods.

When the first fluid is supplied to the motor through the conduit, this fluid, its pressure and flow rate, cause the piston to move between TDC and BDC.

The movement of the piston between TDC and BDC pulls the output shaft 31 with it, which drives the pumping unit, allowing the pumping of a predetermined amount of the second liquid present in the internal volume 335 of the sleeve 330.

When the second liquid reaches the internal volume of the sleeve, from there it passes through the by-pass conduit 600,605 to the outlet conduit, or to the gap between the first tubular body and the second tubular body, where it mixes with the first liquid that has passed through the motor valves.

It should be noted that in this discussion, rigid means not noticeably deformable, i.e. appreciably deformable, under normal working loads to which it is subjected. In other words, a rigid element does not perform the function for which it was designed by means of its own deformation.

An elastic element, on the other hand, means a body that is conformed in such a way that it deforms (only) elastically under the normal working loads to which it is subjected and therefore also (or only) performs its function through its own elastic deformation. It should be noted that the definition “elastic deformation” is to be understood as opposed to “plastic deformation”, where plastic deformation is the type of deformation in which the body subjected to deformation does not return to its original shape once it is no longer subjected to the deforming force.

In the present case a gasket is elastically deformed to adhere to certain surfaces in order to generate a seal, possibly a hermetic seal.

Further, it should be noted that a monolithic body is defined as a body obtained from the solidification of a single casting, or injection, of (a single) material into a mould and, if necessary, subsequent processing of this solidified body by removal of material.

The term to size and with reduced clearance means that the elements with this coupling can slide in relation to each other without any particular effort, i.e. with low friction, and without tilting appreciably with respect to the sliding direction. If, on the other hand, there is a large amount of clearance, the elements may tilt significantly in the direction of travel and get stuck.

The invention thus conceived is susceptible to several modifications and variations, all falling within the scope of the inventive concept.

Moreover, all the details can be replaced by other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to the requirements without for this reason departing from the scope of protection of the following claims.

Claims

1. Proportional volumetric dosing device (1 ,1 ’,1 ”), comprising: a motor (20) provided with:

- an inlet conduit (10) of a first liquid and an outlet conduit (15) of a mixture of the first liquid with a second liquid,

- a tubular body (105) into which the inlet conduit flows,

- a piston (30) provided with a portion (65) slidably inserted into the tubular body (105) and movable along a respective sliding axis (X) between a top dead centre and a bottom dead centre position,

- an output shaft (31 ) integral in sliding with the piston,

- a portion of the base coaxial to the sliding axis (X), and a pump (25,25’) provided with:

- an inlet port for the second liquid,

- a pumping unit of the second liquid, said pumping unit being in fluid communication with the inlet port of the second liquid, being driven by the output shaft (31 ) of the motor and being provided with an outlet (320, 410, 652a) of the second pumped liquid,

- a portion of the base coaxial to the sliding axis (X) and through which the pump is fixed to the motor, wherein the proportional volumetric dosing device comprises:

- a by-pass conduit (600,605) connecting the outlet (320, 410, 652a) of the pumping unit to the outlet conduit (15) of the motor by-passing the inlet conduit (10) and an axial cavity (1 16) of the tubular body comprised between the piston and the inlet conduit, said dosing unit being characterised in that the by-pass conduit (600,605) comprises at least a portion that crosses an interface area between the motor and the pump at said bases.

2. Proportional volumetric dosing device (1 ”) according to claim 1 , wherein said portion of the by-pass conduit crosses a wall of the base portion of the pump and a wall of the base portion of the motor, also crossing an area of mutual contact between said walls.

3. Proportional volumetric dosing device (1 ”) according to claim 2, wherein the pump comprises a sleeve (330) by means of which the pumping unit is fixed to the motor and comprises an inner volume (335) of the sleeve itself in direct fluid communication with the outlet of the pumping unit, wherein the by-pass conduit (605) comprises an inlet port (630) made in an inner surface of the sleeve, a first section extending from the inlet port to the interface area, and a second section made in the motor body extending from the interface area to the outlet conduit, at which there is an outlet port (635) of the by-pass conduit itself.

4. Proportional volumetric dosing device (1 ,1 ’) according to claim 1 , wherein said portion of the by-pass conduit (600) crosses a separating septum (230) in which the output shaft (31 ) is slidably sealingly housed and which divides a volume (335) of the pump downstream of the outlet of the pumping unit from said volume (1 16) of the motor which is at least partially defined by the tubular body and the piston.

5. Proportional volumetric dosing device (1 ,1 ’) according to claim 4, wherein the bypass conduit (600) comprises an inlet port (610) made in a face of the separator septum (230) facing the outlet of the pumping unit, a first section extending from said inlet port towards the tubular body (105) of the motor, and a second section passing through a wall of the tubular body in contact with the separator septum and having an outlet port (615) made in an outer surface of the tubular body or in the outlet conduit.

6. Proportional volumetric dosing device (1 ,1 ’) according to claim 4 or 5, wherein the pump comprises a sleeve (330) by means of which the pumping unit is fixed to the motor and which comprises the volume (335) of the pump downstream of the outlet of the pumping unit, and wherein said separating septum (230) is housed in the tubular body of the motor or in the sleeve of the pump occluding one side thereof.

7. Proportional volumetric dosing device (1 ,1 ’,1 ”) according to claim 1 , wherein the bypass conduit (600,605) is provided with an outlet port (615,635) whose central axis is parallel (coaxial) to a longitudinal axis of the outlet conduit (15).

8. Proportional volumetric dosing device (1 ,1 ’,1 ”) according to claim 3 or 5 or 7, wherein the by-pass conduit (600,605) at its outlet port comprises a nozzle (620) with a restricted cross-sectional area in relation to the rest of the by-pass conduit.

9. Proportional volumetric dosing device (1 ,1 ’,1 ”) according to claim 1 , wherein the bypass conduit does not protrude externally from the pump and the motor body.

10. Proportional volumetric dosing device (1 ,1 ’,1 ”) according to claim 10, wherein the pump comprises a sleeve (330) by means of which the pump is fixed to the motor and which defines an internal volume in fluid communication with the outlet of the pumping unit, and wherein the by-pass conduit does not protrude externally from the sleeve.