vane oil pump with improved operation

Abstract

The invention relates to a vane oil pump (1) comprising a body (2) in which a fixed stator (3) and a rotor (4) rotating tangentially to said stator (3) are located. The pump (1) comprises vanes (5) positioned in radial grooves (6) of said rotor (4) and capable of sliding within these grooves between the stator (3) and a central retaining ring (7) of the stator (3). According to the invention, at least one side wall (8) closes the body (2) by coming into contact with the rotor (4). This side wall (8) comprises at least one connecting channel (10) establishing fluidic communication between a zone (11) of the body (2) that is external to the rotor (4) and in which the pressure is high, and a central zone (12) located inside the rotor (4) and in which the pressure is lower than that of said external zone. Figure 1

Description

Title of the invention: Vane oil pump having improved operation

[0001] The present invention relates to a vane oil pump having improved operation.

[0002] As a reminder, referring to [Fig. 1], a vane oil pump 1 is a volumetric transfer pump. It is generally constituted by a cast iron body 2 inside which there is a fixed stator 3 in the form of a cylindrical wall, and a steel rotor 4 in the form of a cylindrical part, which rotates tangentially to the stator 3. Vanes 5 arranged in the rotor 4 can slide in radial grooves 6 of said rotor 4 and are held in contact with the wall forming the stator 3 by a set of springs and centrifugal force. The vanes of the oil pump in operation are subjected to forces which bring them into contact with the cylindrical wall forming the stator or with a retaining ring. However, these forces can be sufficiently great for wear of the vanes to occur at these two interfaces, either with the stator or with the retaining ring.Such significant wear of the vanes would inevitably lead to malfunction of the oil pump.

[0003] A vane oil pump according to the invention is designed so as to slow down or even eliminate wear of its vanes after several operating cycles thereof.

[0004] The subject of the invention is a vane oil pump comprising a body in which is placed a fixed stator in the form of a cylindrical side wall and a rotor in the form of a cylindrical part placed in the rotor and rotating tangentially to said stator, said pump comprising vanes placed in radial grooves of said rotor and able to slide in these between the stator and a retaining ring placed in a central zone of the body, said vanes remaining permanently in contact with the stator by means of springs and coming punctually into contact with said central ring.

[0005] According to the invention, at least one side wall closes the body by coming into contact with the rotor, said side wall comprising at least one connecting channel putting into fluid communication a zone of the body which is external to the rotor and in which the pressure is high, and a central zone located inside the rotor and in which the pressure is lower than that of said external zone, said connecting channel contributing to balancing said two pressures in order to soften the contact of the vanes against the retaining ring. The principle of an oil pump according to the invention is to implement oil passages between an external zone of the rotor in which the pressure is high, and an inner zone thereof in which the pressure is lower, so as to reduce or even eliminate the pressure differential in said two zones. In this way, the contact between the vanes of the oil pump and the retaining ring will be attenuated, allowing said vanes to wear less quickly, and therefore to maintain their performance within the oil pump for longer. The side wall comprising said at least one connecting channel closes on the body of the oil pump to create a closed and sealed internal space in the body. The connecting channels being made in a side wall which is fixed to the body, do not exert any direct influence on the movement of the rotor relative to the stator as well as on the sliding of the vanes in the radial grooves of the rotor. They will therefore not disturb the operation of the oil pump.The side wall may have several connecting channels, which may or may not be parallel to each other.

[0006] According to a possible characteristic of the invention, the side wall closes a circular end of the rotor considered along its axis of revolution, said at least one connecting channel being located between the side wall of the body and said circular end. The rotor is in the form of a cylindrical part having two circular ends considered along its axis of revolution, the side wall comprising the connecting channel bearing against one of said ends. In other words, this side wall covers said end without disturbing the movement of the rotor relative to the stator.

[0007] According to a possible characteristic of the invention, the side wall of the body has dimensions which are greater than those of the circular end of the rotor against which it is in contact, said side wall projecting radially from said circular end over 360°.

[0008] According to a possible characteristic of the invention, said at least one connecting channel is rectilinear. The fact that the connecting channel is rectilinear is mainly linked to the overall geometry of the oil pump, imposing this particular shape of the connecting channel.

[0009] According to a possible characteristic of the invention, said at least one connecting channel is curved. The fact that the connecting channel is curved is mainly linked to the overall geometry of the oil pump, imposing this particular shape of the connecting channel.

[0010] According to a possible characteristic of the invention, said at least one connecting channel has a cross-section of constant shape and dimension over its entire length. In this way, the conditions for transferring the oil between the outer zone and the inner zone are perfectly controlled.

[0011] According to a possible characteristic of the invention, the cross-section of said at least one connecting channel has a shape to be chosen from a triangle, a rectangle, a circle and an ellipse. The precise shape of the cross-section of the connecting channel is not of paramount importance. On the other hand, it is important that the outline of this cross-section is clean and homogeneous, that is to say free of any secondary relief likely to create harmful turbulence in the oil flowing inside the connecting channel. For example, a star-shaped cross-section is to be avoided in the context of the present invention.

[0012] According to a possible characteristic of the invention, said at least one side wall has at least two connecting channels. The multiplication of connecting channels will promote fluid communication between the zone outside the rotor and the zone inside it, and will make it possible to effectively reduce the pressure differential between said two zones. On the other hand, the presence of too many connecting channels must not bias the operation of the oil pump, by creating a resulting oil passage that is too large between said two zones.

[0013] According to a possible characteristic of the invention, said at least one connecting channel is oriented in the direction of rotation of the rotor. In this way, the oil will tend to penetrate naturally and fluidly into the connecting channel, without creating a break in the movement of the fluid that could be caused by an orientation of the connecting channel in the opposite direction to that of rotation of said rotor.

[0014] According to a possible characteristic of the invention, the oil pump comprises two parallel side walls sealingly closing the body of said pump by coming into contact with two ends of the rotor, each of the two parallel side walls comprising at least one connecting channel. These two parallel side walls will seally close the body of the oil pump containing the oil, in order to prevent any leakage of oil to the outside of the oil pump. Preferably, the two side walls are fixed to the body, each using a seal.

[0015] A vane oil pump according to the invention has the advantage of wearing less quickly than existing oil pumps, thanks to the implementation of simple, but judiciously positioned connecting channels in said oil pump. Indeed, these channels will make it possible to rebalance the oil pressure in the oil pump, between a central zone and a peripheral zone of said oil pump, without requiring a major modification of the structure thereof. In addition, the connecting channels are positioned in said pump without occupying a large volume, which could harm the performance of said oil pump.

[0016] A detailed description of a preferred embodiment of a vane oil pump according to the invention is given below, with reference to the following figures:

[0017] [Fig. 1] [Fig. 1] is a front view of a vane oil pump according to the invention, a front side wall having been removed to view the interior of said oil pump,

[0018] [Fig.2] [Fig.2] is a front view of a rotor of a vane oil pump according to the invention, showing the location of the connecting channels,

[0019] [Fig.3] [Fig.3] is a side view of one end of the rotor of [Fig.2], showing the location of the connecting channels,

[0020] Referring to [Fig.l], a vane oil pump 1 according to the invention is a volumetric transfer pump. It is generally constituted by a cast iron body 2 inside which there are a fixed stator 3 in the form of a cylindrical wall, and a steel rotor 4 in the form of a cylindrical part placed inside the stator 3 and movable in rotation about its axis of revolution. More precisely, the rotor 4 is placed in the stator 3, so that their axes of revolution are parallel but offset from each other, so that the rotor 4 rotates tangentially to the stator 3. Vanes 5 of elongated shape are arranged in radial grooves 6 of said rotor 4 and can slide in said grooves 6 between the wall forming the stator 3 and a retaining ring 7 placed in a central zone of said stator 3.The vanes 5 are kept permanently in contact with the wall forming the stator 3 by a set of springs and centrifugal force. The vanes 5 of the oil pump 1 in operation are therefore subjected to forces, which bring them into contact with the cylindrical wall forming the stator 3 or with the central retaining ring 7. However, these forces can be sufficiently significant for wear of the vanes 6 to occur at their ends, which are in contact either with the stator 3 or with the central retaining ring 7. Such significant wear of the vanes 5 would inevitably lead to poor operation of the oil pump 1, which would quickly become inoperative.

[0021] It should be noted that the body 2 of the oil pump 1 containing the various elements such as the stator 3, the rotor 4, the vanes 5 and the central retaining ring 7 is closed by two side walls 8 not visible in the figures. In this way, said two side walls 8 and said body 2 form a closed and sealed space enclosing said elements.

[0022] In order to reduce the forces exerted on the vanes 5, in particular when they come into contact with the central retaining ring 7, an oil pump 1 according to the invention comprises calibrated connecting channels 10 making it possible to put into fluid communication a first peripheral zone 11 of high pressure situated between the rotor 4 and the stator 3, and a second central zone 12 of lower pressure situated inside the rotor 4. The rotor 4 is materialized by a cylindrical part having two circular ends 14, considered along the axis of revolution of said rotor 4. The two side walls 8 closing the body 2 of the oil pump 1 each come into contact with a circular end 14 of the rotor 4. These side walls 8 have dimensions which are greater than those of the circular ends 14 of the rotor 4, so that that said side walls 8 completely cover said circular ends 14 of said rotor 4 while being in contact with them. In order to remove any ambiguity, these two side walls 8, once they have been mounted on the body 2 of the oil pump 1, are fixed and have no degree of freedom.

[0023] Referring to [Fig. 3], the connecting channels 10 are made in at least one of the two side walls 8 closing the body 2 of the oil pump 1 and coming into contact with a circular end 14 of the rotor 4. These connecting channels 10 are therefore located between the side wall 8 which carries them and the circular end 14 of the rotor 2 against which said side wall 8 is in contact. The connecting channels 10 may be rectilinear or curved depending on the geometry of the oil pump in question 1, and / or the space available therein. The connecting channels 10 of the oil pump 1 may all be curved, or all rectilinear, or may consist of both rectilinear and curved channels. The cross-section of these connecting channels 10 may for example be circular, rectangular, triangular or elliptical.It is important that this cross-section is regular, in order to ensure a homogeneous and fluid flow of the oil in said connecting channels 10. The cross-section of these connecting channels 10 must not have secondary reliefs, likely to create turbulence within the oil flowing in said connecting channels 10. Preferably, the cross-section of each connecting channel 10 is constant over its entire length. To be fully effective, the connecting channels 10 must be oriented in the direction of rotation of the rotor 4 in the stator 3, as indicated by the arrow 13 in [Fig.2].

[0024] The presence of the connecting channels 10 makes it possible to increase the pressure in the second central zone 12 of the rotor 4 as a function of the increase in pressure in the first peripheral zone 11. However, this increase is weighted with the increase in speed N due to the orientation of the connecting channels 10 in the direction of rotation, corresponding to the inclination of an angle [30 as illustrated in [Fig. 2], due to the entrainment of the oil by friction with the surface of the rotor 4, in motion relative to the fixed side wall carrying said connecting channels 10. For an inclination angle [30 equal to 90°, the influence of the speed N is maximum, and for an inclination angle [30 equal to 0°, the influence of the speed N disappears.

[0025] By reducing the pressure differential between the first peripheral zone 11 and the second central zone 12, the contact conditions between the vanes 6 and the retaining ring 7 in the central position will be softened, allowing said vanes 6 to wear less quickly than the vanes 6 of existing oil pumps.

Claims

Claims

1. Vane oil pump (1) comprising a body (2) in which is placed a fixed stator (3) in the form of a cylindrical side wall and a rotor (4) in the form of a cylindrical part placed in the rotor (4) and rotating tangentially to said stator (3), said pump (1) comprising vanes (5) placed in radial grooves (6) of said rotor (4) and able to slide in these between the stator (3) and a retaining ring (7) placed in a central zone of the body (2), said vanes (5) remaining permanently in contact with the stator (3) by means of springs and coming punctually into contact with said central ring (7), characterized in that at least one side wall (8) closes the body (2) by coming into contact with the rotor (4), and in that said side wall (8) comprises at least one connecting channel (10) putting into fluid communication a zone (11) of the body (2) which is external to the rotor (4) and in which the pressure is high,and a central zone (12) located inside the rotor (4) and in which the pressure is lower than that of said outer zone, said connecting channel (10) contributing to balancing said two pressures in order to soften the contact of the vanes (5) against the retaining ring (7).,

2. Oil pump according to claim 1, characterized in that the side wall (8) closes a circular end (14) of the rotor (4) considered along its axis of revolution, and in that said at least one connecting channel (10) is located between the side wall (8) of the body (2) and said circular end (14).

3. Oil pump according to claim 2, characterized in that the side wall (8) of the body (2) has dimensions which are greater than those of the circular end (14) of the rotor (4) against which it is in contact, and in that said side wall (8) projects radially from said circular end (14) over 360°.

4. Oil pump according to any one of claims 1 to 3, characterized in that said at least one connecting channel (10) is rectilinear.

5. Oil pump according to any one of claims 1 to 3, characterized in that said at least one connecting channel (10) is curved.

6. Oil pump according to any one of claims 1 to 5, characterized in that said at least one connecting channel (10) has a cross-section of constant shape and dimension over its entire length.

7. Oil pump according to claim 6 characterized in that the cross section of said at least one connecting channel (10) has a shape to be chosen from a triangle, a rectangle, a circle and an ellipse.

8. Oil pump according to any one of claims 1 to 7, characterized in that said at least one side wall (8) has at least two connecting channels (10).

9. Oil pump according to any one of claims 1 to 8, characterized in that said at least one connecting channel (10) is oriented in the direction of rotation of the rotor (4).

10. Oil pump according to any one of claims 1 to 9, characterized in that it comprises two parallel side walls (8) sealingly closing the body (2) of said pump (1) by coming into contact with two ends (14) of the rotor (4), and in that each of the two parallel side walls (8) comprises at least one connecting channel (10).

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