EP3623618B1 - Pump with to-and-fro system with rack and pinion and use of such a pump - Google Patents

Description

The present invention relates to a pump for a fluid product, the pump being of the type comprising a frame, a piston and a system for driving the piston to move the piston relative to the frame in translation according to a reciprocating movement along an axis displacement, the drive system comprising an input shaft extending along an axis of rotation, a motor adapted to drive said input shaft in rotation about the axis of rotation relative to the frame, and a system of conversion to convert the rotation of the input shaft around the axis of rotation into a translational movement of the piston.

The term "fluid product" is understood here and below to mean a product which has a viscosity of between 1 mPa.s and 2 kPa.s, this viscosity being for example measured using a Brookfield Plan Cone viscometer in normal conditions of temperature and pressure. This expression thus includes products in the liquid state, perfectly deformable and with low viscosity, but also products generally qualified as "pasty", more viscous than liquids and presenting an intermediate state between the liquid state and the solid state. .

The invention also relates to the use of such a pump for pumping a paint or a viscous product, a “viscous product” being defined here and below as a product having a viscosity of between 3000 and 300000 mPa.s.

Pumps of the aforementioned type are known and are commonly used to pump paints and viscous products. Generally, their motor consists of an electric, or pneumatic, or hydroelectric motor.

Most often, the conversion system of such pumps consists of a ball screw. A drawback of this solution is that it requires driving a reversal of the direction of rotation of the motor, which requires the use of a relatively expensive motor. In addition, the ball screw requires initial wedging which complicates the manufacture of the conversion system. In addition, the ball screw has a very limited lifespan.

Another known solution is to use a rack and pinion system as the conversion system. Such a solution is described for example in the document US 2014/0219819 A1 . Nevertheless, this solution still requires driving a reversal of the direction of rotation of the motor.

A third known solution consists in using a connecting rod-crank system to convert the rotation of the input shaft into translation of the pivot. This solution makes it possible to produce a reciprocating movement of the piston despite a constant direction of rotation for the motor. However, it has the disadvantage of requiring complex control of the engine rotational speed to maintain a substantially constant piston speed in each direction.

Finally, a fourth known solution consists in driving with the input shaft a cam against which the shaft of the piston is held in abutment. Again, this solution makes it possible to produce a reciprocating movement of the piston while maintaining a constant direction of rotation for the motor. However, it does not give complete satisfaction, since it is necessary to provide a return system for the piston against the cam which complicates the drive system and reduces the working stroke of the piston.

CN 107 795 449 A , KR 100 781 391 B1 and CN 106 762 500A describe each of the pumps comprising a piston movable according to a reciprocating movement.

An object of the invention is thus to provide a pump whose piston is driven in a simple and economical manner by a motor with a constant direction of rotation.

To this end, the invention relates to a pump of the type according to claim 1.

According to particular embodiments of the invention, the pump also has one or more of the additional characteristics of claims 2 to 10.

The invention also relates to the use of the pump defined above for pumping a paint, a varnish, a viscous product, or another liquid product.

• la Figure 1 est une vue en élévation et en coupe d'une pompe selon l'invention,
• la Figure 2 est une vue d'un détail marqué II de la Figure 1,
• la Figure 3 est une vue d'un détail marqué III de la Figure 1, et
• la Figure 4 est une vue en perspective d'un système de conversion de la pompe de la Figure 1.

Other characteristics and advantages of the invention will appear on reading the following description, given solely by way of example and with reference to the appended drawings, in which:

• the Figure 1 is a view in elevation and in section of a pump according to the invention,
• the Figure 2 is a view of a detail marked II of the Figure 1 ,
• the Figure 3 is a view of a detail marked III of the Figure 1 , and
• the Figure 4 is a perspective view of a pump conversion system from the Figure 1 .

The pump 10 represented on the Figure 1 typically comprises a frame 12 and a pumping unit 14.

With reference to the Figure 2 , the pumping unit 14 comprises, in a conventional manner, a cylindrical chamber 16 for receiving the fluid product to be pumped, and a piston 18.

The chamber 16 is integral with the frame 12 and is oriented along an axis A-A'. It is closed at a first axial end by a first wall 20, and at the opposite axial end by a second wall 22.

Piston 18 is mounted to move in translation inside chamber 16 along said axis A-A'. It achieves a sealed separation between a first part 24 of the chamber 16, which extends from the first wall 20 to the piston 18, and a second part 26 of the chamber 16 which extends from the second wall 22 to the piston 18. Depending on the position of the piston 18 inside the chamber 16, the volume of each of the first and second parts 24, 26 varies.

The piston 18 is integral with a shaft 28 oriented parallel to the axis A-A' and preferably, as shown, substantially coaxial with the axis A-A'. This shaft 28 extends through the second wall 22, in which a through hole 30 is provided for this purpose.

The pumping unit 14 also comprises a fluid product supply 32 to supply the chamber 16 with fluid product, and a fluid product discharge 34 to allow the fluid product to be evacuated from the chamber 16.

The supply 32 comprises a supply inlet 40 for connecting a fluid product supply pipe (not shown), a first supply branch 42 fluidly connecting said inlet 40 to a first supply orifice 44 formed in the first wall 20, and a first supply non-return valve 46 mounted in the first branch 42 so as to allow the circulation of fluid from the inlet 40 to the orifice 44 by prohibiting the discharge of fluid from the port 44 to inlet 40.

The evacuation 34 comprises an evacuation outlet 50 for connecting a fluid product evacuation pipe (not shown), a first evacuation branch 52 fluidly connecting said outlet 50 to a first evacuation orifice 54 made in the first wall 20, and a first evacuation non-return valve 56 mounted in the first branch 52 so as to allow the circulation of fluid from the orifice 54 towards the outlet 50 by prohibiting the discharge of fluid from the outlet 50 to port 54.

Thus, the pumping unit 14 is adapted so that the displacement of the piston 18 from the first wall 20 towards the second wall 22 causes the suction of the fluid product from the inlet 40 in the first part 24 of the chamber 16, and that the displacement of the piston 18 from the second wall 22 towards the first wall 20 causes the discharge of the fluid product out of the first part of the chamber 16, towards the outlet 50.

In the example shown, the pump 10 is a double-acting pump, that is to say the pumping unit 14 is adapted so that the displacement of the piston 18 from the second wall 22 towards the first wall 20 causes also the suction of the fluid product from the inlet 40 in the second part 26 of the chamber 16, and that the displacement of the piston 18 from the first wall 20 towards the second wall 22 causes also the discharge of the fluid product out of the second part 26 of the chamber 16, towards the outlet 50.

For this purpose, the supply 32 also comprises a second supply branch 58 fluidly connecting the inlet 40 to a second supply orifice 60 formed in the second wall 22, and a second supply non-return valve 62 mounted in the second branch 58 so as to allow the circulation of fluid from the inlet 40 to the orifice 60 by prohibiting the discharge of fluid from the orifice 60 to the inlet 40. In addition, the evacuation 34 also comprises a second evacuation branch 64 fluidly connecting the outlet 50 to a second evacuation orifice 66 provided in the second wall 22, and a second evacuation non-return valve 68 mounted in the second branch 64 so as to allow the circulation of fluid from port 66 to outlet 50 by preventing the discharge of fluid from outlet 50 to port 66.

Thus, the pumping unit 14 here consists of a four-ball pump. Alternatively (not shown), the pumping unit 14 consists of a two-ball pump.

Back to the Figure 1 , the pump 10 also comprises a system 70 for driving the piston 18 to move the piston 18 inside the chamber 16 in translation according to a reciprocating movement along the axis A-A'.

With reference to the Figure 3 , this drive system 70 comprises an input shaft 72, a motor 74 for driving said input shaft 72 in rotation about its axis relative to the frame 12, and a conversion system 76 for converting the rotation of the input shaft 72 around its axis in translational movement of piston 18 along axis A-A'.

The input shaft 72 is elongated along an axis B-B' orthogonal to the axis A-A'. It is also rotatably mounted relative to the frame 12 around this same axis B-B'.

The input shaft 72 is thus adapted to occupy different angular positions relative to the frame 12, each angular position being defined by an angle between 0° and 360° relative to a reference position of the shaft 72, a rotation complete shaft 72 around the axis B-B 'bringing the shaft 72 to its initial angular position.

The motor 74 comprises a stator (not shown) integral with the frame 12, and a rotor (not shown) mounted so as to be able to rotate about its axis relative to the frame 12. Said rotor is kinematically linked to the input shaft 72, typically via a reduction gear (not shown), so that the rotation of the rotor drives the rotation of the input shaft 72; alternatively, the rotor constitutes the input shaft 72.

The motor 74 is typically constituted by an electric motor, for example a brushless motor or an asynchronous motor.

The conversion system 76 comprises a carriage 80 mounted to move in translation relative to the frame 12 in a direction parallel to the axis A-A'. This carriage 80 is integral with the piston 18, via the shaft 28.

In the example shown, the carriage 80 has a generally parallelepipedal shape.

The conversion system 76 also includes a guide system 82 to guide the movement of the carriage 80 relative to the frame 12.

This guidance system 82 here comprises a pair of rails 84 together framing the carriage 80 in a direction orthogonal to the axes A-A' and B-B', each rail 84 being parallel to the axis A-A'. The system 82 also comprises, for each rail 84, two rotary rollers 86 mounted on the carriage 80 and forming the interface between the carriage 80 and the rail 84, each roller 86 being centered on its own axis parallel to the axis B-B' and being freely rotatable around this axis relative to the carriage 80.

In the example shown, each roller 86 is positioned at a respective edge of the carriage 80.

The conversion system 76 also includes a conversion device 90 for converting the rotation of the input shaft 72 around its axis B-B' into the reciprocating movement of the carriage 80 and, by this intermediary, of the piston 18 , along the axis A-A'.

According to the invention, this conversion device 90 consists of a to-and-fro system with rack and pinion.

This reciprocating system 90 comprises a half-pinion 92, a first rack 94 able to mesh the half-pinion 92 in a first direction, and a second rack 96 able to mesh the half-pinion 92 in a second direction opposed to the first meaning. By "capable of meshing the half-pinion in a second direction opposite to the first direction", it is understood here and below that, for a constant direction of rotation of the half-pinion 92, the meshing of the half-pinion 92 on the second rack 96 causes half-pinion 92 to move relative to second rack 96 in a direction opposite to the direction of movement of half-pinion 92 relative to first rack 94 when it is meshed with the latter.

The half-pinion 92 is rotatably mounted relative to the frame 12 around the axis BB' and is immobile in translation relative to the frame 12 along the axis A-A'. It is kinematically linked to the input shaft 72 so that the rotation of the input shaft 72 causes the rotation of the half-pinion 92. In particular, the half-pinion 92 is integral with the drive shaft. entry 72.

The half-pinion 92 comprises a toothed angular sector 98, the rest of the half-pinion 92 having no teeth. In other words, the teeth of the half-pinion 92 are all grouped together in the toothed angular sector 98.

The toothed angular sector 98 is continuous and the teeth are regularly distributed in this angular sector 98.

The angular sector 98 has an angular extent less than 170° and preferably between 90° and 130°.

The half-pinion 92 comprises a number N of teeth, this number N here being equal to five, without this being limiting.

The half-pinion 92 is interposed between the racks 94, 96.

Each of the first and second racks 94, 96 is formed in the carriage 80 and is, therefore, integral with the piston 18 and the other rack 94, 96.

Each rack 94, 96 is rectilinear and is oriented substantially parallel to the axis A-A'.

Each rack 94, 96 comprises, in known manner, a body 100 and teeth 102 projecting from this body.

These teeth 102 are preferably N+1 in number, that is to say that each rack 94, 96 comprises one tooth more than the half-pinion 92, the racks 94, 96 having the same number of teeth. Thus, in the example shown, each rack 94, 96 comprises six teeth 102.

Advantageously, all the teeth 102 have the same height, that is to say that the distance separating the body 100 from the top of a tooth 102 is equal to the distance separating the body 100 from the top of each other tooth 102. Thus , it is possible to use for the racks 94, 96 standard racks, and the management of stocks of racks necessary for the production of the pump 10 is facilitated

Racks 94, 96 are spaced apart in a direction orthogonal to axes A-A' and B-B'.

The racks 94, 96 face each other, i.e. the teeth 102 of each rack 94, 96 protrude from the body 100 of the rack 94, 96 in the direction of the other rack 94, 96.

Each tooth of the first rack 94 is, for example, substantially aligned along a direction orthogonal to the axis of displacement A-A' with a corresponding tooth of the second rack 96.

In addition, each tooth 102 of each rack 94, 96 is substantially aligned along said direction orthogonal to the axes AA' and BB' with a corresponding tooth 102 of the other rack 94, 96.

• une première configuration embrayée, dans laquelle le demi-pignon 92 est engrené sur la première crémaillère 94 ; cette configuration est rencontrée lorsque l'arbre d'entrée 72 occupe une position angulaire comprise dans un premier secteur ;
• une première configuration débrayée, dans laquelle le demi-pignon 92 n'est engrené sur aucune des crémaillères 94, 96, ses dents étant orientées à l'opposé du piston 18; cette configuration est rencontrée lorsque l'arbre d'entrée 72 occupe une position angulaire comprise dans un deuxième secteur juxtaposé au premier secteur ;
• une deuxième configuration embrayée, dans laquelle le demi-pignon 92 est engrené sur la deuxième crémaillère 96, comme montré sur les Figures ; cette configuration est rencontrée lorsque l'arbre d'entrée 72 occupe une position angulaire comprise dans un troisième secteur juxtaposé au deuxième secteur et disjoint du premier secteur ; et
• une deuxième configuration débrayée, dans laquelle le demi-pignon 92 n'est engrené sur aucune des crémaillères 94, 96, ses dents étant orientées vers le piston 18; cette configuration est rencontrée lorsque l'arbre d'entrée 72 occupe une position angulaire comprise dans un quatrième secteur interposé entre les premier et troisième secteurs et disjoint du deuxième secteur.

Due to the relatively restricted angular extent of the toothed sector 98 of the half-pinion 92 and the configuration of the racks 94, 96, the half-pinion 92 is configured to, during its rotation, mesh alternately with the first rack 94 and on the second rack 96, thus causing the movement of the carriage 80, and therefore of the piston 18, along the axis AA' alternately in a first direction and in a second direction. It is also configured to, during the transition phases between the first and second racks 94, 96, completely disengage from the rack 94, 96 which it leaves before meshing with the other rack 94, 96. Thus , the reciprocating system 90 has the following different configurations:

• a first engaged configuration, in which the half-pinion 92 is meshed on the first rack 94; this configuration is encountered when the input shaft 72 occupies an angular position comprised in a first sector;
• a first disengaged configuration, in which the half-pinion 92 is not meshed with any of the racks 94, 96, its teeth being oriented away from the piston 18; this configuration is encountered when the input shaft 72 occupies an angular position comprised in a second sector juxtaposed with the first sector;
• a second engaged configuration, in which the half-pinion 92 is meshed on the second rack 96, as shown in the Figures; this configuration is encountered when the input shaft 72 occupies an angular position comprised in a third sector juxtaposed with the second sector and separate from the first sector; and
• a second disengaged configuration, in which the half-pinion 92 is not meshed with any of the racks 94, 96, its teeth being oriented towards the piston 18; this configuration is encountered when the input shaft 72 occupies an angular position comprised in a fourth sector interposed between the first and third sectors and separate from the second sector.

In order to prevent any displacement of the piston 18 in these disengaged configurations, the conversion system 76 also comprises a mechanism 110, represented on the Figure 4 , immobilization of the piston 18 when the reciprocating system 90 is in the disengaged configuration.

With reference to the Figure 4 , this immobilization mechanism 110 comprises four abutment surfaces 112, 114, 116, 118 carried by the carriage 80, and an eccentric 120, that is to say a part eccentric with respect to its axis of rotation, kinematically linked to the input shaft 72 so that the rotation of the input shaft 72 causes the rotation of said eccentric 120 around an eccentric axis constituted here by the axis B-B'.

The abutment surfaces 112, 114, 116, 118 include a first abutment surface 112 and a second abutment surface 114 facing each other spaced apart along the axis A-A'.

Each abutment surface 112, 114 is at least partly orthogonal to the axis A-A'. In the example shown, each abutment surface 112, 114 has the overall shape of a truncated cylinder, a tangent plane of which consists of a plane orthogonal to the axis A-A'. In particular, this truncated cylinder has as its axis an axis parallel to the axis B-B' and is truncated by a plane orthogonal to the axis A-A'.

The abutment surfaces 112, 114, 116, 118 also include a third abutment surface 116 and a fourth abutment surface 118 oriented in opposite directions to each other.

Each abutment surface 116, 118 is at least partly orthogonal to the axis A-A'. In the example shown, each abutment surface 116, 118 has the overall shape of a truncated cylinder, a tangent plane of which is formed by a plane orthogonal to the axis A-A'. In particular, this truncated cylinder has as its axis an axis parallel to the axis B-B' and is truncated by a plane orthogonal to the axis A-A'.

The first and fourth stops 112, 118 are each oriented away from the piston 18. The second and third stops 114, 116 each oriented towards the piston 18.

Along the axis A-A', one encounters successively, starting from the piston 18 and moving away from it: the first stop 112, the third stop 116, the eccentric axis, the fourth stop 118 and the second stop 114. Thus, the first stop 112 and the third stop 116 are each interposed between the eccentric shaft and the piston 18, and the second stop 114 and the fourth stop 118 are arranged opposite the piston 18 relative to the eccentric axis.

The eccentric 120 is adapted to bear against the first and third abutment surfaces 112, 116 when the reciprocating system 90 is in its first disengaged configuration, and to bear against the second and fourth surfaces of stop 114, 118 when the reciprocating system 90 is in its second disengaged configuration.

For this purpose, the eccentric 120 comprises an arm 122 kinematically linked to the input shaft 72 so that the rotation of the input shaft 72 causes the rotation of said arm 122 around the eccentric axis, and a bearing member 124 mounted on said arm 122, said bearing member 124 having a primary bearing surface 126, facing away from the eccentric axis and capable of resting against the first and second abutment surfaces 112, 114, and a secondary bearing surface 128, oriented towards the eccentric axis and capable of resting against the third and fourth surfaces of stop 116, 118.

The arm 122 is in particular secured to the input shaft 72.

The support member 124 here consists of a roller mounted on the arm 122 so as to be, relative to the arm 122, freely rotatable about an axis parallel to the eccentric axis.

This pump 10 is thus particularly suitable for use for pumping a paint or a viscous product, due to the simple and particularly robust system for converting the rotational movement of the motor 74 into a reciprocating movement of the piston 18.

In addition, this pump 10 is particularly stable thanks to the immobilization mechanism 110 which prevents the pump 10 from swallowing the product discharged under the effect of the pressure difference existing between the upstream and downstream circuits.

Although, in the embodiment described above, the reciprocating system 90 only comprises a single half-pinion 92, the invention is however not limited to this single case. Thus, as a variant (not shown), the reciprocating system 90 comprises two half-pinions. In this variant, the two half-pinions are kinematically linked to each other so as to rotate in the same direction, and together they surround the first and second racks 94, 96, which are then not positioned face to face. but back to back.

Other variants of the pump 10 and in particular of the reciprocating system 90 are also possible without departing from the scope of the invention as defined by the appended claims.

Claims (11)

1. A pump (10) for a fluid product, the pump (10) comprising a frame (12), a piston (18), and a drive system (70) for driving the piston (18) to translate the piston (18) relative to the frame (12) back and forth along a displacement axis (A-A'), the drive system (70) comprising an input shaft (72) extending along a rotation axis (B-B'), a motor (74) adapted to rotate said input shaft (72) about the axis of rotation (B-B') relative to the frame (12), and a conversion system (76) for converting the rotation of the input shaft (72) about the axis of rotation (B-B') into translational motion of the piston (18), the conversion system (76) comprising a rack and pinion reciprocating system (90),

   the rack and pinion reciprocating system (90) comprising at least one half-pinion (92) kinematically linked to the input shaft (72) so that rotation of the input shaft (72) causes rotation of the or each half-pinion (92), a first rack (94) integral with the piston (18) and which is able to engage the half-pinion (92) or a first of the half-pinions, in a first direction, and a second rack (96) integral with the piston (18) and which is able to engage the half-pinion (92) or a second of the half-pinions, in a second direction opposite the first direction,

   the conversion system (76) comprising a carriage (80) mounted for translational movement relative to the frame (12), the piston (18) being integral with said carriage (80) and the racks (94, 96) forming part of said carriage (80),

   the rack and pinion reciprocating system (90) having at least one disengaged configuration in which no half-pinion (92) is meshed with either the first rack (94) or the second rack (96), and the conversion system (76) comprises a mechanism (110) for immobilising the piston (18) when the rack and pinion reciprocating system (90) is in the disengaged configuration, said immobilising mechanism (110) comprising:

   - at least one stop surface (112, 114, 116, 118) carried by the carriage (80), and

   - an eccentric (120) kinematically linked to the input shaft (72) such that rotation of the input shaft (72) causes rotation of said eccentric (120) about an eccentric axis, the eccentric (120) being adapted to bear against the abutment surface (112, 114, 116, 118) or at least one of the abutment surfaces (112, 114, 116, 118) when the rack and pinion reciprocating system (90) is in a disengaged configuration,

   characterised in that the eccentric axis is formed by the axis of rotation (B-B').
2. The pump (10) according to claim 1, wherein the rack and pinion reciprocating system (90) comprises a single half-pinion (92), said half-pinion (92) being interposed between the first and second racks (94, 96), said first and second racks (94, 96) facing each other.
3. The pump (10) according to claim 2, wherein each rack (94, 96) comprises at least one more tooth (102) than the half-pinion (92), the racks (94, 96) having the same number of teeth (102).
4. The pump (10) according to any of claims 1 to 3, wherein each rack (94, 96) comprises a plurality of teeth (102), said teeth (102) all having the same height.
5. The pump (10) according to any one of claims 1 to 4, wherein each rack (94, 96) is straight and is oriented substantially parallel to the displacement axis (A-A').
6. The pump (10) according to any one of claims 1 to 5, wherein the conversion system (76) comprises a guide system (82) for guiding the movement of the carriage (80) relative to the frame (12), said guide system (82) comprising at least one pair of rails (84) together framing the carriage (80) in a direction orthogonal to the axis of movement (A-A'), each rail (84) being parallel to the axis of travel (A-A'), and, for each rail (84), at least two rotatable rollers (86) mounted on the carriage (80) and interfacing between the carriage (80) and the rail (84).
7. The pump (10) according to any one of claims 1 to 6, wherein the abutment surfaces (112, 114, 116, 118) comprise a first abutment surface (112) and a second abutment surface (114) spaced apart along the axis of movement (A-A'), the eccentric (120) being interposed between said first and second abutment surfaces (112, 114).
8. The pump (10) according to any one of claims 1 to 7, wherein the eccentric (120) comprises an arm (122) kinematically linked to the input shaft (72) such that rotation of the input shaft (72) causes rotation of said arm (122) about the eccentric axis, and a roller (124) mounted on said arm (122) so as to be, relative to the arm (122), freely rotatable about an axis parallel to the eccentric axis, said roller (124) defining at least one abutment surface (126, 128) of the eccentric (120) against the or each abutment surface (112, 114, 116, 118).
9. The pump (10) according to any of the preceding claims, said pump (10) being a double-acting pump.
10. The pump (10) according to any of the preceding claims, wherein the motor (74) is an electric motor.
11. Use of a pump (10) according to any one of the preceding claims, for pumping a paint, varnish, or a product having a viscosity of between 3,000 and 300,000 mPa.s.

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