EP3161314B1 - Positive-displacement piston pump and rotary distribution means - Google Patents

Description

The present invention relates to the field of piston positive piston pumps.

An interesting application of such a pump relates to the rubber gum feed of an extruder for forming a profile for the manufacture of a vehicle tire. Such a pump can of course be used for all kinds of viscous and liquid products.

Conventionally, a positive displacement pump comprises a product metering piston slidably mounted in a cylinder of the pump body forming a metering chamber, and means for actuating the piston, for example a cam in contact with one end of the latter.

A type of positive displacement pump also comprises a distribution valve rotatably mounted inside a sleeve of the pump body for communicating the metering chamber alternately with an intake chamber and an exhaust chamber of the sleeve, for example. via an orifice provided in the thickness of said sheath.

For this purpose, first and second groups of grooves are formed on the outer surface of the plug and arranged so as to pass in front of the opening of the sleeve during the rotation of the plug in order to successively communicate the metering chamber with the intake chamber and then with the exhaust chamber.

Thus, the pumped product flows from the inlet chamber to the metering chamber, then from this metering chamber to the exhaust chamber through the same orifice. For more details on a pump of this type, one can for example refer to the patent application EP-A1-0 604 888 .

With such a pump, it is necessary to provide a radial functional clearance between the outer surface of the rotary plug and the bore of the sleeve of the pump body receiving the plug. In In addition, this game tends to increase with the existing radial friction and wear between the bushel and the sheath. Therefore, leakage of the product present inside the inlet chamber directly to the exhaust chamber can occur, especially when the pumped product is rubber or other viscous product having a low viscosity.

Moreover, such leaks may also exist along the outer surface of the plug circumferentially between the intake grooves and the exhaust grooves in case of wear of this outer surface, for example by scratching, abrasion, etc., which can be caused by polluting particles contained in the product to be pumped.

With such uncontrolled product flows between the inlet and outlet grooves of the plug and / or between the plug and the barrel of the pump casing, the flow rate of the pump can be irregular.

The present invention aims to remedy this disadvantage.

More particularly, the present invention aims to provide a positive displacement piston pump with a regular flow and simple design.

In one embodiment, the positive displacement pump comprises a product metering chamber, a metering piston slidably mounted within said chamber, a sleeve defining at least a portion of an inlet chamber and a chamber of exhaust of the product, and a product distribution means rotatably mounted inside the sleeve about an axis and adapted to put the metering chamber in communication alternately with the inlet chamber and the exhaust chamber.

The dispensing means comprises an inlet member comprising means for passing the product able to come at least partly opposite an inlet orifice of the metering chamber to put said chamber in communication with the admission chamber. , and an escapement member comprising means for passing the product able to come at least partly opposite an orifice of output of the metering chamber to put said chamber in communication with the exhaust chamber. The intake and exhaust members are located axially on either side of an internal partition wall of the sleeve and each mounted axially in abutment against said partition.

The dispensing means also comprises means for holding the intake and exhaust members in abutment against the inner wall of the sheath.

The dispensing means is adapted to separate the intake and exhaust functions of the product which are each produced by a specific member. The means of passage of the product of each member provide a single function of admission or exhaust. The mounting axially in abutment of each inlet or exhaust member against the wall of the pump body and the maintenance of this axial contact to prevent product leakage between the inlet chamber and the exhaust chamber .

In addition, by the use of two separate members axially separated by the wall of the pump body, the passage means for admission are spaced axially from those provided for the exhaust, which prevents a circumferential flow of product between these means. There is thus an improved internal sealing pump favoring obtaining a regular flow. The flow is no longer linked to the wear of the dispensing means. Moreover, two orifices each specific to the product inlet or to the exhaust are also provided.

Preferably, each of the intake and exhaust members comprises a flat front face mounted axially bearing against the inner wall of the sheath. A planar contact between each intake or exhaust member and the partition promotes obtaining a good seal between the intake and exhaust chambers.

In one embodiment, each of the intake and exhaust members comprises a body provided with means for passing the product, and a friction ring integral in rotation with said body and mounted axially in abutment against the inner wall of the sheath. This arrangement reduces the frictional forces between the intake and exhaust members and the sheath.

In one embodiment, the holding means comprise at least one elastic prestressing means capable of exerting an axial prestressing force on one of the intake and exhaust members.

Thus, it is possible to guarantee the maintenance of the axial contact between the wall of the sheath and between the intake and exhaust members before the first use of the pump, ie when the product to be dosed does not fill the admission chambers. and exhaust. This axial prestressing force also makes it possible to compensate for axial play between the intake and exhaust members and between the partition in the event of frictional wear.

The dispensing means may also comprise a common support shaft on which the intake and exhaust members are mounted. Preferably, the holding means are also mounted on said shaft.

Advantageously, the intake and exhaust members and the inner wall of the sleeve are annular.

The internal partition may be located axially between the inlet and outlet ports of the metering chamber. In one embodiment, the inlet and outlet ports are formed in the thickness of the sheath.

The passage means may comprise grooves provided on the outer surfaces of the intake and exhaust members.

• la figure 1 est une vue schématique partielle en coupe d'une pompe volumétrique selon un exemple de réalisation de l'invention dans une position d'admission du produit, et
• la figure 2 est une vue schématique partielle en coupe de la pompe de la figure 1 dans une position d'échappement dudit produit.

The present invention will be better understood on reading the detailed description of an embodiment taken by way of non-limiting example and illustrated by the appended drawings in which:

• the figure 1 is a partial schematic sectional view of a positive displacement pump according to an exemplary embodiment of the invention in an intake position of the product, and
• the figure 2 is a partial schematic sectional view of the pump of the figure 1 in an exhaust position of said product.

On the figures 1 and 2 an exemplary embodiment of a volumetric pump, referenced 10 as a whole, is provided for dispensing a viscous product, such as an elastomer which may be unvulcanized rubber.

The pump 10 comprises a pump body 12 provided with a sleeve 14 delimiting an admission chamber 16 and a discharge or exhaust chamber 18, and a cylinder 20 defining a metering chamber 22. The sleeve 14 presents an axis XX 'of elongation and the cylinder 20 has an axis YY' of elongation orthogonal to the axis X-X '. The cylinder 20 is fixed on the sheath 14. In the illustrated embodiment, the metering chamber 22 is shifted radially outwardly with respect to the intake and exhaust chambers 18. In the entire embodiment of FIG. description, the terms "axial, radial and circumferential" are defined by considering the axis X-X '.

The pump 10 also comprises a product dispensing means 24 which is rotatably mounted inside the sleeve 14 about the axis X-X '. As will be described in more detail below, the dispensing means 24 is designed on the one hand to alternately communicate the metering chamber 22 with the inlet chamber 16 and the exhaust chamber 18 via two separate bodies, and secondly to prevent product leakage between these chambers. The intake and exhaust chambers 16 and 18 are separated from one another by the distribution means 24.

In the exemplary embodiment illustrated, the pump 10 further comprises an endless type feeding screw 26 disposed in the inlet chamber 16 and making it possible to move the product from an insertion orifice (not shown). the chamber towards the dispensing means 24 and put under pressure the pumped product. The distribution means 24 is secured to the screw 26 and the axis XX 'of said means coincides with that of the screw. Alternatively, it is possible to provide another booster means to obtain the forced mechanical transfer of the product to the dispensing means 24 against which said product is pressed under pressure. In another variant, the pump may be devoid of booster means depending on the product to be dosed.

The pump 10 further comprises a product dosing piston 28 which is slidably mounted along the axis YY 'inside the metering chamber 22. The sliding movement of the metering piston 28 is perpendicular to the axis XX The piston 28 is slidably mounted between maximum and minimum volume positions of the metering chamber 22 which correspond respectively to bottom and top dead spots of said piston.

During an admission phase of the product illustrated in figure 1 under the effect of the pressure of the product which is dispensed by the dispensing means 24 from the inlet chamber 16 to the metering chamber 22, the piston 28 moves from the top dead center to the bottom dead point. This displacement towards the bottom dead center is illustrated schematically by the arrow referenced 30. During an escape phase illustrated in FIG. figure 2 , the piston 28 moves from the bottom dead center to the top dead center under the effect of actuating means (not shown) of said pump. This movement towards the top dead center is represented by the arrow referenced 32. The actuating means may for example comprise a cam mounted in contact against the lower end of the metering piston 28. The rotational movements of the distribution means 24 and translation of the piston 28 are synchronized.

The dispensing means 24 comprises a member 34 for admitting the product, a member 36 for exhausting said product axially spaced from said intake member, and a common support shaft 38 of axis XX 'on which said members are mounted. The inlet and outlet members 34, 36 annular are integral in rotation with said shaft 38 via a key 40. The intake and exhaust members 34, 36 can slide axially on the shaft 38 along the key 40. The shaft 38 is integral with the screw 26 for feeding.

The intake and exhaust members 34, 36 are arranged axially on either side of an internal partition 42 of the sleeve and axially bear against said partition. The partition 42, of annular shape, axially separates the inlet chamber 16 from the exhaust chamber 18. The partition 42 extends inwards from the bore of the sheath. The partition 42 extends radially to the vicinity of the support shaft 38 while remaining radially at a distance therefrom. The partition 42 has two opposite flat front faces against which each of the intake and exhaust members 34, 36 is axially supported.

The inlet member 34 is disposed in the inlet chamber 16. The inlet member 34 comprises a body 44 and a friction ring 46 mounted axially bearing against said body. The body 44 and the friction ring 46 are integral in rotation with the shaft 38 via the key 40. The body 44 is mounted axially in abutment against a shoulder 38a of the shaft and the friction ring 46 comes axially in abutment against the wall 42 of the sheath. The shoulder 38a of the shaft is here located at an axial end of said shaft and extends radially outwards. The shoulder 38a forms a means for maintaining the axial position of the intake member 34 bearing against the partition 42 of the sleeve. The holding means is axially mounted in abutment against the inlet member 34. Alternatively, it may be possible to replace the shoulder 38a with another axial stop member, for example of the circlip type.

The body 44 comprises an axial cylindrical outer surface 44a centered in the bore of the sleeve 14 and two opposite end faces 44b, 44c radially defining said outer surface. The front face 44b is oriented axially on the side of the inner wall 42 of the sleeve and forms a bearing face for the friction ring 46. The front face 44c is oriented axially on the side of the product introduction orifice of the admission room 16. The front face 44c is mounted axially in abutment against the shoulder 38a of the shaft.

The body 44 of the intake member further comprises a plurality of recesses or grooves 44d formed on the outer surface 44a and opening on the end face 44c. The grooves 44d are spaced from each other in the circumferential direction, preferably evenly.

During rotation of the inlet member 34, and more generally of the distribution means 24, the grooves 44d run past an inlet orifice 48 of the metering chamber 22. The grooves 44d ensure the fluidic communication of the metering chamber 22 with the admission chamber 16.

The escapement member 36 has a similar design to that of the admission member 34. The exhaust member 36 is disposed in the exhaust chamber 18. The exhaust member 36 comprises a body 50 and a friction ring 52 mounted axially bearing against said body 50. The body 50 and the ring friction 52 are integral in rotation with the shaft 38 by means of the key 40. The friction ring 52 is mounted axially in abutment against the wall 42 of the sleeve axially on the opposite side to the inlet member 34.

The body 50 comprises an axial cylindrical outer surface 50a centered in the bore of the sleeve 14 and two opposite end faces 50b, 50c radially defining said outer surface. The end face 50b is oriented axially on the side of the inner wall 42 of the sheath and forms a bearing face for the friction ring 52. The front face 50c is oriented axially on the side of an evacuation orifice (not shown) the product of the exhaust chamber 18.

The body 50 of the exhaust member 36 also comprises a plurality of recesses or grooves 50d formed on the outer surface 50a, opening on the end face 50c and spaced relative to each other in the circumferential direction. During the rotation of the distribution means 24, the grooves 50d run past a outlet orifice 54 of the metering chamber 22. The grooves 50d ensure the fluidic communication of the metering chamber 22 with the exhaust chamber 18.

The grooves 50d of the exhaust member are arranged relatively to the grooves 44d of the inlet member so that when one of the grooves 44d comes opposite the inlet orifice 48 of the metering chamber 22, none of the grooves 50d of the exhaust member is positioned opposite the outlet orifice 54. In this position of admission of the product into the metering chamber 22, the outlet orifice 54 is closed off by the outer surface 50a of the exhaust member as shown in FIG. figure 1 .

Conversely, in the exhaust position of the product from the metering chamber 22, one of the grooves 50d comes opposite the outlet orifice 54 and the outer surface 44a of the inlet member seals the inlet port 48. Thus, the dispensing means 24 makes it possible to put the metering chamber 22 in communication with alternately the inlet chamber 16 and the exhaust chamber 18.

In the exemplary embodiment illustrated, the inlet orifice 48 and the outlet orifice 54 are formed in the thickness of the sleeve 14 of the pump body and open into the metering chamber 22. The orifices 48, 54 radially extend in the thickness of the sheath 14. The orifices 48, 54 are located radially facing the metering piston 26 and arranged radially beyond the top dead center of said piston. The orifices 48, 54 are located axially on either side of the partition 42, respectively on the side of the inlet chamber 16 and the exhaust chamber 18.

The rotary friction rings 46, 52, of generally annular shape, are mounted axially in abutment against the fixed partition 42 of the pump body. The partition 42 is in axial contact with the friction ring 46 of the intake member on one side and is in axial contact with the friction ring 52 of the exhaust member on the other side. Each friction ring 46, 52 comprises a front face 46a, 52a here radial plane mounted axially in contact against the partition 42 inside the sheath. Advantageously, each friction ring 42, 52 is made of a low coefficient of friction material and may have self-lubricating properties and good wear resistance, for example bronze, graphite, etc.

The dispensing means 24 further comprises an annular washer 56 mounted on the shaft 38 and coming axially in abutment against the exhaust member 36, and a nut 58 which is screwed onto a threaded portion of said shaft (not referenced) and blocking axially the washer 56. The washer 56 is mounted axially in abutment against the end face 50c of the exhaust member 36. The washer 56 may for example be of the Belleville type. The washer 56 is able to exert an axial force on the exhaust member 36 so as to apply an axial prestress tending to keep said member against the wall 42 of the sheath. Alternatively, it is possible to use any other resilient biasing means with axial elasticity able to exert an axial prestressing force on the exhaust member 36. It could also be possible to combine several prestressing means axially stacked between the nut 58 and the exhaust member 36.

The washer 56 and the nut 58 form means for holding the axial position of the exhaust member 36 in abutment against the partition 42 for separating the sleeve. These holding means are mounted axially in abutment against the exhaust member 36. Alternatively, it may be possible not to provide an elastic washer 56 and mount the nut 58 directly against the exhaust member 36. In another variant, it could also be possible to replace the nut with another axial stop element, for example of the circlip type.

Thanks to the invention, there is a pump comprising a distribution means designed to separate the intake and exhaust functions of the product which are each produced by a specific element. To ensure this separation, the passage means of each member provide a single function of admission or exhaust. Axial contact between each inlet member or exhaust and the bulkhead of the pump body makes it possible to avoid product leaks between the intake chamber and the exhaust chamber in an efficient and economical manner, even with the presence of a radial functional clearance between the dispensing means and the bore of the barrel of the pump body. The obtaining of a regular flow is favored.

In operation, the pressure of the product applied axially against the inlet member and / or the pressure of the product applied axially against the escapement member promotes the axial plating of said members against the partition wall of the sleeve. In the case of frictional wear, the pressure of the product on the intake side and / or the pressure of the product on the exhaust side make it possible to maintain this plating. The axial biasing force exerted by the washer also promotes the maintenance of axial contact between the wall of the sleeve and between the intake and exhaust members in case of wear.

Furthermore, given the arrangement of the inlet and exhaust members axially on either side of the partition wall of the sleeve, the passage means for the admission of the product are offset axially relative to the means of passage for the exhaust. This avoids a flow of product between the means provided for admission and those for the exhaust in case of wear on the outer surface of the dispensing means.

In the exemplary embodiment illustrated, each intake or exhaust member comprises a body and a separate friction ring to limit friction with the wall of the pump body. In a variant, each member could be constituted solely by the body and could preferably comprise an anti-friction and anti-wear coating. In another variant, a friction ring or a coating could be provided on each side face of the fixed internal wall of the pump body.

In another variant, each of the intake and exhaust members could comprise, in replacement of the ring of friction, a seal, for example ring or lip (s), rubbing against the partition wall of the sleeve. Alternatively, it could also be possible to provide a partition wall comprising, on each of its end faces, a seal coming to rub against the associated intake or exhaust member.

Claims (10)

1. Positive-displacement pump comprising a product metering chamber (22), a metering piston (28) mounted inside said chamber so as to slide, a sleeve (14) at least partially delimiting an intake chamber (16) and an exhaust chamber (18) for said product, and a product dispensing means (24) that is mounted so as to be able to rotate inside the sleeve and is able to place the metering chamber alternately into communication with the intake chamber and the exhaust chamber, characterized in that the dispensing means comprises:

   - an intake member (34) comprising product passage means (44d) that are able to at least partially face an inlet orifice (48) of the metering chamber in order to place said chamber in communication with the intake chamber, and

   - an exhaust member (36) comprising product passage means (50d) that are able to at least partially face an outlet orifice (54) of the metering chamber in order to place said chamber in communication with the exhaust chamber,

   - said intake and exhaust members (34, 36) being situated axially on either side of an internal partition (42) of the sleeve and each being mounted so as to bear axially against said partition, and

   - holding means (38a, 56, 58) for keeping the intake and exhaust members (34, 36) bearing against the internal partition (42) of the sleeve.
2. Pump according to Claim 1, wherein each of the intake and exhaust members (34, 36) comprises a flat front face (46a, 52a) mounted so as to bear axially against the internal partition (42) of the sleeve.
3. Pump according to Claim 1 or 2, wherein each of the intake and exhaust members (34, 36) comprises a body (44, 50) provided with passage means (44d, 50d), and a friction ring (46, 52) that rotates as one with said body and is mounted so as to bear axially against the internal partition (42) of the sleeve.
4. Pump according to any one of the preceding claims, wherein the holding means comprise at least one elastic preloading means (56) that is able to exert an axial preloading force on one of the intake and exhaust members (34, 36).
5. Pump according to any one of the preceding claims, wherein the dispensing means (24) comprises a common support shaft (38) on which the intake and exhaust members (34, 36) are mounted.
6. Pump according to Claim 5, wherein the holding means (38a, 56, 58) are mounted on said shaft (38).
7. Pump according to any one of the preceding claims, wherein the intake and exhaust members (34, 36) and the internal partition (42) of the sleeve are annular.
8. Pump according to any one of the preceding claims, wherein the internal partition (42) is situated axially between the inlet and outlet orifices (48, 54) of the metering chamber.
9. Pump according to any one of the preceding claims, wherein the inlet and outlet orifices (48, 54) are formed in the thickness of the sleeve (14).
10. Pump according to any one of the preceding claims, wherein the passage means (44d, 50d) comprise grooves formed in the outer surfaces of the intake and exhaust members (34, 36).

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