THREAD FOR AN AIR-DRYER CARTRIDGE

Abstract

A thread connection is provided between a filter cartridge and its base, as well as to a filter cartridge comprising such a thread. The thread has a reversed load flank.

Claims

1. A threaded device comprising a crest, a root, a load flank, a stab flank, and a pitch, wherein the crest is oriented rearward compared to a screwing axis and wherein the load flank makes an angle with an axis Y orthogonal to the screwing axis, wherein the angle is comprised between 15 and 45 and in that the crest is beveled, in such a way that its extremity is provided with a flat portion.

2. A threaded device according to claim wherein the stab flank 14 makes an angle with an axis orthogonal to the screwing axis wherein is comprised between 20 and 50 and wherein is higher than .

3. A threaded device according to claim 1 wherein the crest is provided with a flat portion which makes an angle with the screwing axis, or an axis parallel to the screwing axis, wherein is comprised between 0 and 30.

4. A threaded device according to claim 1 wherein the device is either a tilter or a housing comprising a filter.

5. A threaded device according to claim 4 wherein the filter is an air-dryer filter cartridge.

6. A threaded assembly comprising: a threaded device 1, comprising a crest, a root, a load flank, a stab flank, wherein the crest is oriented rearward compared to a screwing axis, and having an internal diameter D2 and an external diameter D3, a threaded base 2, comprising a crest 21, a root 22, stab flank 24, and a load flank 23, wherein the crest 21 is oriented toward the screwing direction of the device 1, and having an internal diameter D1 and an external diameter D wherein D1=DX*p, D3=D2X*p, and D2=D+J where X denotes a variable comprised between 1 and 2, p denotes the pitch of the thread, and J denotes the clearance, wherein at least the crest of the threaded device is beveled, in such a way that its extremity is provided with a flat portion.

7. A threaded assembly according to claim 6, wherein the load flank 13 and the load flank 23 each forms an angle with an axis orthogonal to the screwing axis, and wherein is comprised between 15 and 45.

8. A threaded assembly according to claim 6, wherein the stub flank 14 and the stab flank 23 each forms an angle with an axis orthogonal to the screwing axis, and wherein is comprised between 15 and 50.

9. A threaded assembly according to claim 6, wherein is greater than .

10. A threaded assembly according to claim 6, wherein the contact area between the load flank 13 of the device and the load flank 23 of the base 2 is at least a line corresponding to a medium diameter Dm, wherein $\mathrm{Dm}=\frac{D+D.Math..Math.3}{2}.$

11. A threaded assembly according to claim 6, wherein the contact area between the load flank 13 of the device and the load flank 23 of the base 2 extends on a distance d abroad Dm, wherein $d\text{'}\frac{D-D.Math..Math.3}{2}.Math..Math.\cos .Math..Math..$

12. A threaded assembly according to a claim 6, wherein the device is a filter or a housing comprising a filter.

13. A threaded assembly according to claim 12, wherein the filter is an air filter cartridge.

14. A vehicle equipped with a device as in claim 1.

15. A vehicle equipped with a threaded assembly as in claim 6.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1: view of a filter 1 screwed on the basis 2

[0013] FIG. 2: Cross section of the threaded part A of the device 1

[0014] FIG. 3: Cross section of the assembly of the device 1 and the base 2.

DETAILED DESCRIPTION

[0015] The present invention is directed to a device 1, adapted to be connected to a base 2, by the means of a threaded portion A. The threaded device 1 is for example a disposable filter or a bowl comprising a disposable filter. The profile of the threaded portion A of the device 1 comprises a crest 11, a root 12, a load flank 13, and a stab flank 14, which are organized helicoidally from one end to the other end of the threaded portion A, according to a pitch p. The device 1 is screwed on the base 2 following the screwing axis X-X. The load flank 13 is oriented rearward compared to the screwing direction X-X, in such a way that when a pressure P, or any other ripping out force, is applied to the device 1, then a force F is oriented inwardly, and increases the cohesion between the device 1 and the base 2. The rearward orientation of the load flank 13 is defined by an acute angle with an axis parallel to the screwing axis X-X passing through the root 12. The angle between the load flank 13 and the adjacent root 12 may be comprised between 45 and 90, more preferably between 60 and 80. The rearward orientation of the load flank is also characterized by an angle with an axis Y orthogonal to the screwing axis X-X. The angle may be comprised between around 15 and around 45. The angle is advantageously comprised between around 20 and around 45. The angle is preferably comprised between 25 and 35.

[0016] The stab flank 14 is also oriented rearward to the screwing direction X-X, in such a way that it forms an obtuse angle with the adjacent root 12, or with an axis parallel to the screwing axis X-X passing through the root 12. The angle between the stab flank 14 and the adjacent root 12 is preferably comprised between 95 and 160, more preferably between 100 and 120. The orientation of the crest 11 is also characterized by the fact that the stab flank 14 forms an angle with an axis Y orthogonal to the screwing axis X-X. The angle may be comprised between around 15 and around 50. It is advantageously comprised between around 20 and around 45. The angle is preferably comprised between around 25 and 40.

[0017] The load flank 13 and the stab flank 14 may be parallel to each other, meaning that the angles and are identical. It can be advantageous that is greater than , in such a way that the thickness of the crest 11 is decreasing from its base to its external end. Such a thicker base provides more resistance to the thread. In a preferred aspect, is 10% to 20% greater than .

[0018] The extremity of the crest 11 may be rounded. Advantageously, the crest 11 is beveled, in such a way that its extremity is provided with a flat portion q. The flat portion q allows a clearance between the crest 11 of the threaded portion A of the device 1 and the root 22 of the threaded part of the base 2. The advantage is that no resistance is provided in this part of the thread when screwing or unscrewing the device 1. The further advantage is that in case the pressure P, or any other ripping out force, is strong enough to stress the thread, there is enough space to allow the crest 11 moving toward the root 22 of the thread of the base 2. Thus, the surface of contact between the load flank 13 and the load flank 23 of the base 2 is increased and the strength of the assembly is reinforced. The flat portion q forms an angle with the screwing axis X-X comprised between around 5 and around 30. The angle is preferably comprised between around 10 and around 20. The flat portion q may extend from the load flank 13 until the stab flank 14 or from the load flank 13 until an intermediate position on the crest 11, thus providing an angular shape of the crest 11. The flat portion g preferably extends from the load flank 13 until around the middle of the crest 11.

[0019] The thread of the base 2 is complementary to the thread of the device 1, in such a way that the device 1 can be screwed on the base 2, and form an assembly, as shown in FIG. 3. In particular, the profile of the threaded portion of the base 2 comprises a crest 21, a root 22, a load flank 23 and a stab flank 24. The crest 21 may be provided with a flat portion q wherein q can make an angle with the screwing axis X-X, or any other parallel axis, comprised between around 5 and around 30, preferably between around 10 and around 20. The flat portion q may extend from the load flank 23 to the stab flank 24, or from the load flank 23 to an intermediate position on the crest 21. The flat portion q preferably extends from the load flank 23 until around the middle of the crest 21

[0020] In the assembly, the threaded part of the base 2 has an external diameter D, determined on the external extremity of the crest 21, and an internal diameter D1, determined in the fund of the root 22. D1 is defined according to the following rule:

D1=DX*p,

[0021] Wherein

[0022] D is the external diameter of the threaded part of the base 2, determined on the extremity of the crest 21,

[0023] D1 is the internal diameter of the threaded part of the base 2, determined in the fluid of the root 22,

[0024] X is a variable comprised between 1 and 2, preferably between 1.2 and 1.8, and more preferably between 1.3 and 1.5, and

[0025] P denotes the pitch of the thread.

[0026] D may be comprised between around 20 mm and around 500 mm, depending of the size and/or the shape of the filtering device. It is preferably comprised between around 30 mm and around 50 mm. It is more preferably comprised between around 35 mm and around 45 mm.

[0027] In the assembly, the threaded portion A of the device 1 has an internal diameter D2, determined in the fund of the root 12, and an external diameter D3, determined at the extremity of the crest 11. D3 is defined according to the following rule:

D3=D2X*p,

[0028] Wherein

[0029] D3 denotes the external diameter of the threaded portion A, determined at the extremity of the crest 11,

[0030] D2 denotes the internal diameter of the threaded portion A of the device 1, determined at the fund of the root 12,

[0031] X denotes a variable comprised between 1 and 2, preferably between 1.2 and 1.8, and more preferably between 1.3 and 1.5, and

[0032] p denotes the pitch of the thread, and

wherein D2=D+J

[0033] where J denotes the clearance between the device 1 and the base.

[0034] The assembly is maintained by the means of a contact area between the load flank 13 of the device 1 and the load flank 23 of the base 2. It has to be noted that in the assembly, the flat portion q of the crest 11 and the flat portion q of the crest 21, may increase or reduce the contact area between the device 1 and the base 2, depending on the angle and/or the extent of the flat portions q and q across the corresponding crests 11 and 21. The flat portions q and q are therefore determined in such a way that the contact area between the device 1 and the base 2 is at least a line of contact. Preferably, q and q are symmetrical, meaning that the contact area is at least a line corresponding to the medium diameter Dm, wherein

[00001]$\mathrm{Dm}=\frac{D+D.Math..Math.3}{2}$

[0035] The contact area between the load flank 13 and the load flank 23 may be broadened around Dm, to a distance d corresponding to the distance between the 2 flat portions q and q. The maximal value of the distance d is

[00002]$\frac{D-D.Math..Math.3}{2}.Math..Math.\cos .Math..Math..$

[0036] The distance d may vary according to the pressure P, which is applied to the assembly. Due to the angle , at least a part of the force F is directed inwardly and allows to increase the distance d, thus increasing the contact area between the device 1 and the base 2.