Hydraulic coupling device

1 . A hydraulic coupling device comprising:

an inner sleeve having a tapered outer surface,

an outer sleeve having a tapered inner surface mounted on the tapered outer surface of the inner sleeve,

a nut screwed onto the inner sleeve, and

a cylinder formed separately from the outer sleeve and secured to the outer sleeve, the cylinder having a frontal face axially abutting against a frontal face of the outer sleeve to form a joint,

wherein at least part of the nut extends into the cylinder,

wherein a surface of the cylinder forms a first wall of a chamber, a surface of the nut forms a second wall of the chamber and a surface of the outer sleeve forms a third wall of the chamber,

wherein the chamber is fillable with a hydraulic fluid,

wherein the chamber is radially defined by the tapered outer surface of the inner sleeve and the surface of the cylinder and axially defined by the surface of the nut and the surface of the outer sleeve,

wherein the cylinder, the nut and the outer sleeve are configured such that a fluid pressure increase in the chamber presses the outer sleeve axially away from the nut, and

wherein a) the frontal face of the cylinder and/or the frontal face of the outer sleeve is provided with a coating having a coefficient of friction higher than a coefficient of friction of the frontal face of the cylinder and the coefficient of friction of the frontal face of the outer sleeve, and/or b) at least one protrusion extends from the frontal face of the cylinder into a complementary recess in the frontal face of the outer sleeve or at least one protrusion extends from the frontal face of the outer sleeve into a complementary recess in the cylinder.

2 . The device according to claim 1 ,

wherein the cylinder is formed of a first material and the outer sleeve is formed from a second material different than the first material.

3 . The device according to claim 1 ,

wherein the cylinder protrudes radially outwards with respect to a radially outermost surface of the outer sleeve.

4 . The device according to claim 1 ,

wherein the nut comprises a main portion having a first radial width and a nose having a second radial width less than the first radial width, the nose protruding axially towards the outer sleeve.

5 . The device according to claim 4 , further comprising:

a first seal radially interposed between the inner sleeve and the nose, and

a second seal radially interposed between the cylinder and the nose.

6 . The device according to claim 5 , further comprising:

a third seal axially interposed between the outer sleeve and the cylinder.

7 . The hydraulic coupling device according to claim 1 ,

wherein the frontal face of the cylinder includes at least one protrusion extending into a complementary recess in the frontal face of the outer sleeve or the frontal face of the outer sleeve includes a at one protrusion extending into a complementary recess in the cylinder.

8 . The device according to claim 7 ,

wherein the frontal face of the cylinder and/or the frontal face of the outer sleeve is provided with a coating having a coefficient of friction higher than a coefficient of friction of the frontal face of the cylinder and the coefficient of friction of the frontal face of the outer sleeve.

9 . The device according to claim 8 ,

wherein the coefficient of friction of the coating is greater than or equal to 0.3.

10 . The device according to claim 8 ,

wherein the coefficient of friction of the coating is greater than or equal to 0.45.

11 . The device according to claim 7 ,

wherein the cylinder protrudes radially outwards with respect to a radially outermost surface of the outer sleeve.

12 . The device according to claim 7 ,

wherein the nut comprises a main portion having a first radial width and a nose having a second radial width less than the first radial width, the nose protruding axially towards the outer sleeve.

13 . The device according to claim 12 , further comprising:

a first seal radially interposed between the inner sleeve and the nose, and

a second seal radially interposed between the cylinder and the nose.

14 . The device according to claim 1 ,

wherein the nut includes a main portion having a first outer diameter and a nose having a second outer diameter less than the first outer diameter,

wherein a first seal is radially interposed between the inner sleeve and the nose, wherein a second seal is radially interposed between the cylinder and the nose,

wherein a third seal is axially interposed between the outer sleeve and the cylinder,

wherein the cylinder is made of a material different from a material of the outer sleeve,

wherein the cylinder protrudes radially outwards with respect to a radially outermost surface of the outer sleeve, and

wherein the nose extends axially from the main portion towards the outer sleeve.

15 . The device according to claim 1 ,

wherein the tapered outer surface of the inner sleeve forms a fourth wall of the chamber,

wherein the second wall of the chamber extends radially and faces the third wall of the chamber, and

wherein the first wall of the chamber faces the fourth wall of the chamber.

16 . The device according to claim 15 ,

including an injection conduit having a first end opening into the chamber and a second end opening located in an outer surface of the device.

17 . The device according to claim 16 ,

wherein the outer surface of the device comprises a radially outermost surface of the outer sleeve, and

wherein the first end of the injection conduit is located in the third wall of the chamber.

18 . The device according to claim 16 ,

wherein the pressure increase in the chamber is caused by a fluid output from the first end of the injection conduit filling the chamber, and

wherein the chamber is configured such that the fluid contacts the first wall of the chamber and the second wall of the chamber and the third wall of the chamber when the chamber is filled with the fluid.

19 . The device according to claim 1 ,

wherein the chamber is filled with a fluid, and

wherein the first wall of the cylinder is directly contacted by the fluid.

20 . The device according to claim 1 ,

including an injection conduit having a first end opening into the chamber and a second end opening located in an outer surface of the device.