EP1167756B1 - Axial piston pump - Google Patents

Abstract

The cranked axis axial piston pump has a split rotor concentrically aligned containing an outer drive element (8) and an inner barrel (3). This barrel (3) contains the axially aligned pistons (6) reciprocating in chambers whose face (4) is pressed against the port plate (2) by the effect of a compression spring (11). This configuration reduces friction and allows compensation between the mating faces of the port plate and the barrel. The cranked hydraulic pump with axial pistons (6) consists of a rotating barrel (3) with a central axis (X) co-operating with a distribution port plate (2) associated with a support surface (4) set at right angles to this axis (X). The barrel (3) has a series of axial drillings (5) in which are mounted in a sliding fashion the corresponding pistons (6). A drive (8) distinct from the barrel (3) is provided to rotate about the axis (X) which ensures on one part the centring and driving of the barrel (3) about the axis of rotation (X) and on the other part the reaction for a spring (11) pushing the support surface (4) of the barrel (3) against the port plate (2).

Description

The present invention relates to the field of hydraulic pumps, including piston pumps axial axes of the broken axis type.

In general, axial piston pumps usually used include a body in which is rotatably mounted on its central axis a barrel presenting a series of axial holes in each from which slides a piston whose end is constraint to remain substantially in a fixed plane not perpendicular to the axis of the cylinder, causing their reciprocating motion in the holes during the rotation of said barrel.

The holes with their piston define and cylinders of varying volume in communication with suction and discharge ports of the pump through a dispensing ice fixed rise in the pump body and cooperating with the axial bearing face of the barrel on which open axial drilling. This ice cream dispenser presents two bean-shaped recesses diametrically opposed and connected respectively to the suction port and at the discharge port.

Document FR-A-1 261 358 thus describes a pump barrel, which is however not the type with broken axis. The barrel of this pump is in two coaxial bodies, rigidly secured by fixing bolts and centering studs. The spring providing support barrel against the dispensing ice is interposed between a shoulder of the lower body and the cap central of a rotating and oscillating hat, itself interposed between a central ball and spans hemispherical formed on the axial pistons. Such arrangement induces high friction prohibiting high rotational speeds.

Document FR-A-1,456,563 describes a pump in which the barrel is held in support against the dispensing ice by an elastic washer within reach taper against a counterpart shouldered shoulder on the support of the distribution ice, so with high friction. The centering of the barrel is furthermore provided by a central tube secured to the support of the ice cream dispenser. The trainer has therefore for only function to drive the cylinder in rotation, without intervene for the centering of the cylinder or for the pressing said barrel against the dispensing ice. The structure of such a pump is extremely complex, and involves high friction limiting diets Operating.

NL-A-248 888 finally illustrates a pump broken axis in which the cylinder is driven in rotation by a coach screwed on the cylinder, in being centered on a fixed axis. The support against ice distribution is ensured by Belleville washers in support against a ring mounted on a central axis integral with the support of the dispensing ice. The coach has again only function to drive the cylinder in rotation.

If we know today how to obtain faces of support of a flatness pushed, the tolerances of machining, especially the perpendicularity of the bearing surface to the axis of rotation of the barrel, make the deformations during operation do not guarantee that the barrel is permanently supported by all its bearing surface on the dispensing ice.

Moreover, to prevent the end of the piston does not slide on the board materializing the plane fixed, a classic improvement of this type of pumps is to turn this tray with the barrel along an axis normal to the fixed plane and concurrent with that of the barrel, by means of a homokinetic connection, by example a meshing with bevel gears. A link is then advantageously provided between each piston axial and the plate, rotated at both ends. We have thus eliminated any sliding friction between moving parts, except for the sliding of the piston his piercing.

Also as part of this development, the axial support of the barrel on the distribution window is obtained in a known manner by a spring bearing on the central area of the plateau, for example by through a central ball secured to the platter, and pushing the barrel against the ice of distribution. The spring is installed between two moving parts between them, which generates friction sliding between the spring and at least one of the parts, resulting in wear and particle emission polluting the inside of the pump.

In addition, the effort of the spring is added to those of rods forcing the pistons into the holes of the barrel to give a significant effort on the plateau, which overloads the bearings concerned.

The aim of the invention is to overcome these disadvantages by proposing a hydraulic pump to axial pistons, in particular of the broken axle type, not having the aforementioned drawbacks and limitations.

This problem is solved thanks to a pump comprising a rotary barrel with a central axis cooperating with a distribution window associated with a surface bearing substantially perpendicular to this axis, barrel having a plurality of axial bores in which are mounted sliding pistons corresponding, the said pump being remarkable in that that a driver separate from the cylinder is provided for rotate along a substantially coincident axis of rotation with said central axis, said coach providing a share the centering and rotational drive of the barrel along said axis of rotation, and secondly the support of an elastic means pressing the support surface the barrel against the dispensing ice.

Thus disengaged from the coach, the barrel is free to move axially and angularly under the effect of the spring to compensate for defects alignment of its support surface on the ice of distribution during rotation. Moreover, the effort thrust spring is taken over by the coach, avoiding to solicit the other parts of the pump. In addition, the spring is installed between two substantially immobile parts between them, thereby avoiding any sliding friction of the spring on one of the rooms.

According to an advantageous characteristic, the trainer receives the barrel in a hollow part, a reach inside the center coach the barrel on the axis of rotation, leaving free the axial sliding of the barrel with respect to the coach.

Advantageously, the reach is located substantially mid-axial length of the barrel.

As a result, parasitic radial forces due to pistons are countered substantially at the level of their introduction.

Preferably, the centering allows a certain angular movement of the barrel with respect to the coach.

Thus, the barrel is free to move angularly to stay permanently perfectly plated on the ice cream dispenser.

According to another advantageous characteristic, the connection in rotation of the barrel and the driver is provided by equivalent mechanical means in form matches carried by said barrel and coach. It may be a cooperation of two symmetrical pins on one of these elements, with homologous cavities practiced on the other element, or as a variant of a cooperation of grooves one of those items at the scope level with some hollow counterparts practiced on the other element.

The rotational drive thus produced induces a pure couple on the barrel, preserving the freedom of movement of the barrel with respect to the coach.

Advantageously, the coach has a transverse wall substantially perpendicular to its axis rotation on an inner side of which is compressed the elastic support means of the barrel against ice cream.

This wall against the effort of the means elastic and transmits it to the pump body via the link rotation of the coach on the body (connection by example provided by means of bearings), without this strain on other parts of the pump or create parasitic friction.

In an important embodiment in which the axial pistons are mounted articulated on a plateau rotational axis of rotation contributing to the axis of the coach, the plateau is advantageously linked in rotation to the coach, preferably using a conical gear.

In this case, the parasitic force introduced by the tooth contact of the bevel gear in addition to the couple of training is filtered by the coach, thus sparing the barrel. Moreover, the movements of the barrel do not disturb the conditions of meshing.

Advantageously, the tray is secured in rotation with the driving shaft of the pump.

According to a particular provision, in the case where it is a pump in which the axial pistons are articulated to the plate by means of connecting rods spherical ends, the plateau receives the ends tie rods in shaped associated receptacles, which are held on the board by means of a flange common circular connected to the plate by a screw Central.

• la figure 1 représente la coupe longitudinale d'une pompe hydraulique selon l'invention ;
• la figure 2 est une vue partielle en perspective éclatée représentant l'agencement du barillet, de la glace de distribution et de l'entraíneur dans une pompe selon l'invention.

Other characteristics and advantages will emerge more clearly on reading the description which follows of the figures of the appended drawings, among which:

• Figure 1 shows the longitudinal section of a hydraulic pump according to the invention;
• Figure 2 is a partial exploded perspective view showing the arrangement of the barrel, the dispenser ice and the coach in a pump according to the invention.

Referring to Figure 1, a pump according to the invention comprises a pump body 1 consisting of two parts 1 a and 1 b hosting the components of the pump. Part 1 a receives a distribution window 2 cooperating with a cylinder 3 according to a bearing surface denoted 4 perpendicular to the axis marked X of revolution of the barrel 3. This barrel 3 comprises a series of axial holes 5, (c ' that is to say extending parallel to the axis of revolution or central axis X) to serve as guides to pistons 6. A conduit 7 communicates the face 4 with the interior of the volume of space cylindrical delimited by each bore 5 and the piston 6 associated. It is through these ducts 7 that the oil is admitted or discharged into the cylindrical spaces.

Surrounding the barrel 3 is rotatably mounted a driver 8 composed of a cylindrical portion 9 accommodating the barrel 3, a transverse wall 10 forming a support for a spring 11 plating the barrel 3 against the dispensing window 2, and a conical pinion 12. The driver 8 is here made in the form of a unitary piece, but it may alternatively be provided that the transverse wall 10 is an insert. In this case, it will be provided an axial abutment, reported (a ring for example) or not (a shoulder for example), to ensure the axial locking of the transverse wall 10, this locking being maintained permanently by the action of the spring 11. the driver 8 is rotatably mounted on the portion 1a of the body 1, by means of bearings 13 in slant range, allowing the free rotation of the driver in a substantially axis coinciding with the central axis X of the barrel 3, and realizing its axial stop. These bearings 13 transmit the force from the spring 11 to the part 1a of the body 1.

The coach 8 includes the part cylindrical 9 receiving the barrel 3 in its interior, and it is provided with the transverse wall forming a support spring 11, which wall is either integrally with said cylindrical wall 9 is reported.

The barrel 3 is centered on the axis of rotation of the coach 8 by an inner reach 24 of the coach 8, bearing on a consistent range associated with the barrel 3. The short axial length of the scope, as well as the circumferential set installed preferably allows a certain angular deflection of the barrel 3 with respect to the coach 8, according to values that of course remain low but are sufficient to allow the barrel to float to hold perfectly against the distribution ice in permanence under the effect of the spring 11.

Furthermore, the driver 8 is provided with a conical pinion 12 intended to cooperate with a pinion 16 homologous arranged on a drive shaft 14 rotatably mounted by means of bearings 15 oblique range on the portion 1b of the body 1, and disposed along an axis Y which is concurrent with the X axis. This shaft 14 thus has at its end a conical pinion 16 meshing with the conical pinion 12 of the coach. On the face of this shaft 14 forming a plate 33 facing the driver 8, are disposed axially grains 17 each having a cylindrical portion 18 snaking into a bore 19 associated with the face of the shaft 14, and each having a spherical receptacle 20 swiveling the spherical end 21 of an associated rod 22, the other end 23 also spherical is rotated on the corresponding piston 6. The bore 19 is made substantially opposite the trace of the axis of the piston 6 on a plane normal to the Y axis passing through the center of the receptacles 20 of the grains 17. The grains 17 are connected to the plate 33 by a flange circular 34 reported, common to all grains, by means of a central screw 35.

The rods 22 pass through the wall transverse 10 by means of lights made in said wall 10. A light may be provided by rod 22, or alternatively lights that are common to several rods 22. In case this wall would be reported on the coach 8, we must ensure that that this wall is stopped in rotation with respect to the coach 8, to prevent this wall 10 turns with respect to coach 8 and come up against the connecting rods 22.

The central part of the plate 33 having been released from the support of the spring 11 as is known in the prior art, one can indeed take advantage of it for housing a screw 35 for holding the grains 17, and to realize the connection of the grains 17 to the plate 33 in a very simple, regardless of the number of grains. Such a connection makes it possible not to bind the diameter of distribution of the grains 17 on the plate 33 to the diameter of the shaft 14 at the level of the bearings thereof.

In FIG. 2, the barrel 3 can be distinguished support on the distribution ice 2 presenting two through-holes 25,26 through-holes in the form of beans intended to port holes 5 of the barrel 3 either with the repression, or with suction of the pump.

The coach 8 is presented in partial section, which reveals a cylindrical scope 24 come internally to the coach 8, which cooperates here with a range 27 counterpart of the barrel 3, located substantially at mid-axial length of it. The axial length of the range is reduced for, with the operating clearance installed between the two pieces, allow a slight floating of the barrel 3 with respect to the coach 8, so that the barrel 3 can constantly come against the dispensing ice cream 2, even if the bearing surface 4 of the barrel 3 or the ice cream dispenser 2 is not perfectly perpendicular to the X axis of rotation of the coach 8.

During the operation of the pump, links 22 are not always perfectly aligned with the axis of the pistons 6. This results in parasites normal to the axis of the pistons 6, whose resultant substantially passes through a normal median plane to the axis X of the cylinder 3. By providing the scope for this level, we ensure that these efforts do not generate parasitic spill torque of the barrel 3 with respect to the coach 8.

Moreover, a pin 28 of the barrel 3 is shown cooperating with the sidewall 29 of a notch 30 made in the cylindrical wall 9 of the coach 8, this with a view to rotating the barrel 3 by the coach 8. We have planned here an arrangement symmetrical, to make sure that the coach 8 forces the barrel 3 in rotation by means of a pure torque. Good understood, we can foresee a variant in which the pins 28 are integral with the coach 8, and the notches 30 are provided in the barrel, or any other arrangement using means equivalent counterparts, such as splines to the right of the span 24, these grooves being provided on one of the said coach and barrel, and cooperating with homologous depressions provided on the other of these elements (variant not illustrated here).

The invention is not limited to the particular mode which has just been described, but contrary any variant, which with means equivalent, reproduce the characteristics essential elements described here.

In particular, we can link coach 8 to a shaft leading from the pump, in which case the plate 33 will be driven by the coach 8.

Moreover, to bind in rotation the plate 33 at coach 8, we can consider other types of connections, such as a universal joint, by friction Or other.

Finally, the separation of the coach 8 from the barrel 3 also applies to axial piston pumps in line whose plate 33 is fixed in rotation, and on which slide pads at the end of the pistons axial 6, or axial piston pumps made of variable displacement line by inclination of the axis of rotation of the plate relative to the axis of the barrel, or by tilting the tray itself.

Claims (12)

1. A hydraulic pump having axial pistons (6), the pump comprising a rotary rotor (3) with a central axis (X) co-operating with an associated distribution seat (2) via a bearing surface (4) that is substantially perpendicular to said axis (X), said rotor (3) presenting a plurality of axial bores (5) slidably receiving corresponding pistons (6), the pump being characterized in that a driver (8) separate from the rotor (3) is provided to rotate about an axis of rotation that essentially coincides with said central axis (X), said driver (8) serving firstly to center and rotate the rotor (3) about said axis of rotation (X), and secondly to apply resilient thrust (11) to press the bearing surface (9) of the rotor (3) against the distribution seat (2).
2. A pump according to claim 1, characterized in that the driver (8) receives the rotor (3) in a hollow portion (31), and in that a bearing surface (24) formed inside the driver (8) centers the rotor (3) on the axis of rotation (X), while leaving the rotor (3) free to slide axially relative to the driver (8).
3. A pump according to claim 1 or claim 2, characterized in that the bearing surface (24) is situated axially substantially halfway along the rotor (3).
4. A pump according to any preceding claim, characterized in that the centering leaves the rotor (3) with a certain amount of freedom to move angularly relative to the driver (8).
5. A pump according to any preceding claim, characterized in that the rotor (3) and the driver (8) are linked in rotation by corresponding mechanical means of complementary shapes carried by said rotor (3) and driver (8).
6. A pump according to claim 5, characterized in that the rotary link between the rotor (3) and the driver (8) is provided by co-operation between two symmetrical lugs (28) provided on one of said elements and complementary cavities (29) formed in the other element.
7. A pump according to claim 5, characterized in that the rotary link between the rotor (3) and the driver (8) is provided by co-operation of fluting formed on one of the elements at the bearing surface (24) with complementary fluting formed on the other element.
8. A pump according to any preceding claim, characterized in that the driver (8) has a transverse wall (10) substantially perpendicular to its axis of rotation (X), with resilient means (11) compressed against an inside face thereof to thrust the rotor (3) against the distribution seat (2).
9. A pump according to any preceding claim, in which the axial pistons (6) are hinged to a rotary swashplate (33) whose axis of rotation (Y) intersects the axis (X) of the driver (8), characterized in that the swashplate (33) is coupled to rotate with the driver (8).
10. A pump according to claim 9, in which the rotary coupling is provided by means of bevel gearing (12, 16).
11. A pump according to claim 9 or claim 10, characterized in that the swashplate (33) is constrained to rotate with the drive shaft (14) of said pump.
12. A pump according to any one of claims 9 to 11, in which the axial pistons (6) are hinged to the swashplate (33) by means of links (22) having spherical ends (21, 23), the pump being characterized in that the swashplate (33) receives the ends of the links (21) in associated shaped sockets (20) which are held to the swashplate (33) by means of a common coupling plate (34) connected to the swashplate (33) by means of a central bolt (35).

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