Air-dryer cartridge and helical spring for an air-dryer cartridge

Abstract

An air-dryer cartridge for a compressed air preparation system of a utility vehicle includes a drying agent container having a first housing part and a second housing part movable relative to each other, a cartridge housing for holding the drying agent container, and a helical spring is arranged to preload the second housing part in a direction to reduce a volume of the drying agent container. The helical spring has multiple coils, including a first outer coil at a first end of the helical spring and a second outer coil at a second end of the helical spring. At least one of the first and second outer coils has a greater diameter than inner coils of the helical spring between the first and the second end of the helical spring.

Claims

1. An air-dryer cartridge for a compressed air preparation system of a commercial vehicle, comprising: a drying agent container configured to hold a drying agent, the drying agent container including a first housing part and a second housing part movable relative to one another; a cartridge housing configured to receive the drying agent container; and a helical spring having a plurality of coils, the helical spring being configured to pretension the second housing part relative to the first housing part in a direction which minimizes a volume of the drying agent container, wherein a first outer coil at a first end of the helical spring has a larger diameter than inner coils of the helical spring between the first and a second end of the helical spring such that at least a portion of at least one of the inner coils is in contact with the first housing part or the second housing part when the helical spring is in an installed position, and the second housing part of the drying agent container includes at least one guide element configured to guide the helical spring, the at least one guide element located concentrically within the helical spring and having an axial height at least one-half of an axial height of the helical spring in an installed position.

2. The air-dryer cartridge as claimed in claim 1, wherein a second outer coil at the second end of the helical spring has a larger diameter than the inner coils of the helical spring.

3. The air-dryer cartridge as claimed in claim 2, wherein the first outer coil and the second outer coil of the helical spring are geometrically the same.

4. The air-dryer cartridge as claimed in claim 1, wherein the helical spring is supported against a surface that is curved in a direction away from the drying agent container.

5. The air-dryer cartridge as claimed in 2, wherein one or more of the first outer coil of the helical spring in an installed state of the helical spring is spaced apart from a first adjacent one of the inner coils, and the second outer coil of the helical spring in the installed state of the helical spring is spaced apart from a second adjacent one of the inner coils.

6. The air-dryer cartridge as claimed in claim 5, wherein in an non-installed state of the helical spring, one or more of an internal diameter of the first outer coil is larger by less than a wire diameter size of the helical spring than an external diameter of the first adjacent inner coil, and an internal diameter of the second outer coil is larger by less than the wire diameter size of the helical spring than an external diameter of the second adjacent inner coil.

7. The air-dryer cartridge as claimed in claim 1, wherein the helical spring on a side facing away from the second housing part of the drying agent container is supported by at least 1.2 coils.

8. The air-dryer cartridge as claimed in claim 7, wherein the helical spring on a side facing away from the second housing part of the drying agent container is supported by at least 1.4 coils.

9. The air-dryer cartridge as claimed in claim 1, wherein at least one part of the inner coils of the helical spring forms a cylindrical portion of the helical spring.

10. The air-dryer cartridge as claimed in claim 1, wherein a wire of the helical spring has a substantially circular cross section.

11. The air-dryer cartridge as claimed in claim 1, wherein the first end of the helical spring is supported on one of the second housing part of the drying agent container and the cartridge housing, and the second end of the helical spring is supported on the other of the second housing part of the drying agent container and the cartridge housing.

12. The air-dryer cartridge as claimed in claim 1, further comprising: a cover disposed between the drying agent container and the cartridge housing such that the cover is immovable relative to the first housing part of the drying agent container; and the helical spring is supported on the second housing part of the drying agent container and on the cover.

13. A helical spring for an air-dryer cartridge having a drying agent container configured to hold a drying agent with a first housing part and a second housing part movable relative to one another, and a cartridge housing configured to receive the drying agent container, comprising: a helical spring having a plurality of coils, the helical spring being configured to pretension the second housing part relative to the first housing part in a direction which minimizes a volume of the drying agent container, wherein one or more of a first outer coil at a first end of the helical spring and a second outer coil at a second end of the helical spring has in a larger diameter than at least one inner coil of the helical spring between the first and the second ends of the helical spring such that at least a portion of at least one of the inner coils is in contact with the first housing part or the second housing part when the helical spring is in an installed position, and the helical spring is configured to be guided by at least one guide element of the second housing part concentrically within the helical spring and having an axial height at least one-half of an axial height of the helical spring in an installed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a sectional view of a conventional air-dryer cartridge.

(2) FIG. 2 shows an enlarged detailed view of the air-dryer cartridge of FIG. 1.

(3) FIG. 3 shows a sectional view of an air-dryer cartridge according to a first embodiment of the invention.

(4) FIG. 4 shows an enlarged detailed view of the air-dryer cartridge of FIG. 3.

(5) FIG. 5 shows a sectional view of an air-dryer cartridge according to a second embodiment of the invention.

(6) FIG. 6 shows an enlarged detailed view of the air-dryer cartridge of FIG. 5.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) In order for the present invention to be better understood, the construction of a conventional air-dryer cartridge will first be explained in an exemplary manner.

(8) FIG. 1 shows the construction of the conventional air-dryer cartridge 10, and FIG. 2 shows the helical spring 9 used in said air-dryer cartridge 10 in more detail.

(9) The air-dryer cartridge 10 typically has a cartridge housing 5 having a closed housing cover and a flange 14 having at least one air inlet 15 and one air outlet 16. A drying agent container which is at least partially filled with a drying agent (granulate) 4 and which has a first housing part 2 having a plurality of air-flow openings and a second housing part 3, designed as a granulate cover, having a plurality of air-flow openings 34 is disposed in the cartridge housing 5. The flange 14 is attached to the cartridge housing 5 by means of a base plate 17, wherein the base plate 17 in the configuration visualized in FIG. 1 is connected to the cartridge housing 5 by way of a flanged seam. In order for the air-dryer cartridge 10 to be assembled on an air-dryer housing, the flange 14 on the cartridge neck thereof having the air outlet 16 is provided with an internal thread by way of which the air-dryer cartridge 10 can be screwed onto the air-dryer housing.

(10) At least one filter element 7 which in the embodiment of FIG. 1 is perfused in the radial direction of the drying agent container by the compressed air that enters the air-dryer cartridge 10 by way of the air inlet 15 is disposed between the flange 14 and the first housing part 2 of the drying agent container. After filtration, the compressed air flows upward through the intermediate space between the cartridge housing 5 and the first housing part 2 of the drying agent container and by way of the air-flow openings 34 in the second housing part 3 reaches the interior of the drying agent container. After perfusing the drying agent 4, the de-humidified compressed air exits the air-dryer cartridge 10 by way of the air-flow openings in the first housing part 2 and the air outlet 16.

(11) The second housing part 3 is designed as a drying agent cover which is inserted so as to be movable (in the upward/downward direction in FIG. 1) into a container opening 6 of the first housing part 2. The drying agent (granulate) 4 is held under a defined pretensioning so that a defined air passage cross section is maintained in the drying agent container over the service life of the air-dryer cartridge 10. A helical spring 9 which is supported on the second housing part 3 of the drying agent container, on the one hand, and on the curved housing cover of the cartridge housing 5, on the other hand, is disposed between the cartridge housing 5 and the drying agent container.

(12) As is illustrated in FIGS. 1 and 2, a substantially cylindrical helical screw 9 having a plurality of coils of identical diameter is usually used in conventional air-dryer cartridges 10. In order for the bearing face between the helical spring 9 and the cartridge housing 5 to be enlarged, the helical screw 9 is provided with ground ends 91, as can be seen in particular in FIG. 2. Pushing in a sharp edge at the end of the helical spring 9 into the cartridge housing 5 is to be prevented in this way. The ground ends 91 of the helical spring 9 are usually provided with a coating for the purpose of anti-corrosion protection.

(13) FIGS. 3 and 4 show the construction of an air-dryer cartridge according to a first embodiment of the invention.

(14) The air-dryer cartridge of FIGS. 3 and 4 differs from the conventional air-dryer cartridge shown in FIGS. 1 and 2 by way of the design embodiment of the helical spring for the defined pretensioning of the drying agent in the drying agent container. The construction and the functional mode of the air-dryer cartridge according to the invention otherwise correspond to that of the conventional air-dryer cartridge described above.

(15) In particular, the air-dryer cartridge 10 of this embodiment has a cartridge housing 5 having a flange 14 and a base plate 17, as well as a drying agent container, formed from a first housing part 2 and from a second housing part 3, for receiving a drying agent (granulate) 4. The second housing part 3 serves as a drying agent cover and is inserted in the container opening 6 of the first housing part 2 so as to be movable relative to the first housing part 2. As can be seen in particular in FIG. 4, the second housing part 3 is provided with a multiplicity of air-flow openings 34 through which the compressed air, after perfusing the filter element 7, can make its way into the interior of the drying agent container so as to be de-humidified by the drying agent 4 contained in said drying agent container.

(16) Moreover, a plurality of guide elements are configured on the second housing part 3. In the present embodiment, an inner guide element 31 which is disposed so as to be centric and which is designed, for example, as a substantially cylindrical mandrel is provided. Moreover, an annular outer guide element 32 which is disposed so as to be substantially coaxial with the inner guide element 31 is provided in the present embodiment. These guide elements 31, 32 serve the positioning of the helical spring 1 in the assembly of the air-dryer cartridge 10 and for holding the helical spring 1 in the correct position thereof over the service life of the air-dryer cartridge 10. The guide elements can also be dispensed with, only the inner guide element 31 can be provided, or only the outer guide element 32 can be provided in other embodiments of the invention.

(17) The cartridge housing 5 and the first housing part 2 of the drying agent container are disposed so as to be immovable relative to one another, while the second housing part 3 of the drying agent container is movable relative to the first housing part 2 and also relative to the cartridge housing 5. The drying agent 4 in the drying agent container can thus be held under a defined pretensioning by means of the helical spring 1, wherein the helical spring 1 is supported between the second housing part 3 of the drying agent container and the outwardly curved housing cover of the cartridge housing 5.

(18) As opposed to conventional air-dryer cartridges, the helical spring 1 of the air-dryer cartridge 10 according to the invention does not have a purely cylindrical design. As is illustrated in particular in FIG. 4, the helical spring 1 at the first end thereof (upper end in FIGS. 3 and 4) has a first outer coil 11, and at the second end thereof (lower end in FIGS. 3 and 4) has a second outer coil 13. A plurality of inner coils 12 lie therebetween.

(19) The outer coils 11, 13 of the helical spring 1 have in each case a diameter which is larger than the diameter of the inner coils 12. The helical spring 1 in FIG. 4 is shown in the installed compressed state of said helical spring 1. By virtue of the difference in diameter of the coils, it is possible for the second outer coil 13 to move upward while being compressed, without impacting on the inner coil 12 that is adjacent to said second outer coil 13. Likewise, it is possible for the first outer coil 11 to move somewhat downward while being compressed, without impacting on the inner coil 12 that is adjacent to said first outer coil 11. The first outer coil 11 can thus bear across a large area on the concave internal contour of the cartridge housing 5 without herein contacting the inner coil 12 that is adjacent to said first outer coil 11.

(20) The first and the second outer coil 11, 13 herein preferably have only a minor spacing from the inner coils 12 that are adjacent to said first and said second outer coil 11, 13, such that helical springs do not catch on or thread into one another in the manufacturing process. Depending on the wire diameter of the helical spring, said spacing in the non-installed state of the helical spring 1 is in the range of, for example, approximately 0.5 mm to approximately 1.5 mm. This radial spacing between the mutually adjacent coils is generally at maximum, for example, approximately 50% of the wire diameter and at least approximately 15% of the wire diameter. The delimitation of the radial spacing between the coils is a must in particular in the region of the spring end of the helical spring 1 and is not required across the entire outer coil 11, 13.

(21) In terms of an improved distribution of forces from the helical spring 1 to the cartridge housing 5 it is advantageous in this context for the helical spring 1 to bear on the housing cover of the cartridge housing 5 by way of approximately 1.5 coils, for example.

(22) On account of the positive distribution of forces of the helical spring 1 to the cartridge housing 5 the cartridge housing 5 as compared to the conventional construction can be embodied having a purely cylindrical helical spring 9 having a thinner wall thickness. This leads to savings in terms of material and a reduction in weight.

(23) Furthermore, the geometries of the two outer coils 11, 13 and of the inner coils 12 are substantially symmetrical. This means that the helical spring 1 illustrated in FIG. 4 can also be installed in a reversed orientation, that is to say “upside down”, the functionality being identical.

(24) Furthermore, the helical spring 1 according to the invention does not have any ground ends. The increased manufacturing complexity which would be required for the production of a helical spring 9, shown in FIGS. 1 and 2, of a conventional air-dryer cartridge 10 is thus dispensed with. A non-coated wire which is wound to form the helical spring and the spring ends of the outer coils of which are ground, upon which the wire of the helical spring has to be coated for the purpose of anti-corrosion protection is usually used for the helical spring 9 of the conventional air-dryer cartridge 10. As opposed therefor, a coated wire can be used and wound directly for the helical spring 1 of the air-dryer cartridge 10 according to the invention, such that the additional manufacturing steps of grinding and coating are dispensed with.

(25) In order for the guiding function of the inner guide element 31 of the second housing part 3 to be supported, at least one part of the inner coils 12 forms a substantially cylindrical portion. Apart from the improved positional guiding for the helical spring 1, this design embodiment also results in a kinking tendency of the helical spring 1 that is reduced as compared to pure dual-cone springs. The inner guide element 31 in the installed state of the helical spring 1 preferably protrudes into this helical spring 1 by way of at least one full inner coil 12 of the cylindrical portion of the helical spring 1. The inner guide element 31 in the exemplary embodiment shown protrudes into the helical spring 1 by way of more than half the height of the helical spring 1. The inner guide element 31 likewise reduces the kinking risk of the helical spring 1.

(26) By virtue of the smaller diameter of the inner coils 12, a helical spring 1 having a wire thickness that is thinner as compared to the conventional cylindrical helical spring 9 of FIGS. 1 and 2, without the spring force of said helical spring 1 being reduced. As a result, material and weight can be saved.

(27) In a tested embodiment of the invention the height of the helical spring 1 in the non-installed state was approximately 55 mm, the external diameter of the outer coils 11, 13 of the helical spring were at maximum approximately 41 mm, the internal diameter of the inner coils 12 was approximately 17 mm, and approximately 2.5 cylindrical inner coils 12 were present.

(28) In another embodiment of the invention (not illustrated) the helical spring 1 has only one first outer coil 11 having an enlarged diameter, while the second outer coil 13 has substantially the same diameter as the inner coils 12.

(29) FIGS. 5 and 6 show the construction of an air-dryer cartridge according to a second embodiment of the invention.

(30) The air-dryer cartridge 10 of this second embodiment differs from that of the first embodiment in particular by way of the design embodiment of the cartridge housing and the assembly of the latter on an air-dryer housing.

(31) In particular, the air-dryer cartridge 10 of this embodiment has a cartridge housing 5 that is releasably fastened, for example snap-fitted, to a flange 14 having a bayonet protrusion 18, and has a drying agent container, formed from a first housing part 2 and from a second housing part 3, for receiving a drying agent (granulate) 4. The second housing part 3 serves as a drying agent cover and is inserted in the container opening 6 of the first housing part 2 so as to be movable relative to the first housing part 2. As can be seen in particular in FIG. 6, the second housing part 3 is provided with a multiplicity of air-flow openings 34 through which the compressed air after perfusing the filter element 7 can make its way into the interior of the drying agent container so as to be de-humidified by the drying agent 4 contained in said drying agent container.

(32) An inner guide element 31 which is disposed so as to be centric and which is designed as a substantially cylindrical mandrel, for example, is provided on the second housing part 3. This inner guide element 31 serves for positioning the helical spring 1 in the assembly of the air-dryer cartridge 10 and for holding the helical spring 1 in the correct position thereof over the service life of the air-dryer cartridge 10. The guide element can also be dispensed with in other embodiments of the invention.

(33) An additional cover 20 is disposed between the cover portion of the cartridge housing 5 and the drying agent container. This cover 20 is fixedly connected to the first housing part 2 of the drying agent container. This connection is preferably designed as a snap-fit connection which comprises first connection elements 22 on the cover 20 and second connection elements 24 on the first housing part 2 of the drying. For example, the first connection elements 22 can be designed as belts which are guided from the cover 20 around the drying agent container and in the manner of a tie rod engage behind a second connection element 24 that is designed as a protrusion on the first housing part 2 of the drying agent container.

(34) The cover 20 within the cartridge housing 5 and the first housing part 2 of the drying agent container are thus disposed so as to be immovable relative to one another, while the second housing part 3 of the drying agent container is movable relative to the first housing part 2 and also relative to the cover 20. The drying agent 4 in the drying agent container can thus be held under a defined pretensioning by means of the helical spring 1, wherein the helical spring 1 is supported between the second housing part 3 of the drying agent container and the outwardly curved cover 20.

(35) This construction mode of the air-dryer cartridge 10, with the exception of in particular the helical spring 1 designed according to the invention, is in principle known from, for example, EP 2 448 801 B1, to the entire contents of which in terms of the construction and functional mode reference is hereby made.

(36) The helical spring 1 of the air-dryer cartridge 10 of this embodiment is configured in a manner analogous to that of the first embodiment of FIGS. 3 and 4.

(37) On account of the positive distribution of forces of the helical spring 1 to the cover 20, said cover 20 as compared to the conventional construction can be embodied by way of a purely cylindrical helical spring 9 having a thinner wall thickness. This leads to a saving in terms of material and a reduction in weight.

(38) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF REFERENCE SIGNS

(39) 1 Helical spring (according to the invention)

(40) 2 First housing part of the drying agent container

(41) 3 Second housing part of the drying agent container, in particular drying agent cover, or granulate cover, respectively

(42) 4 Drying agent, in particular drying agent granulate

(43) 5 Cartridge housing

(44) 6 Container opening

(45) 7 Filter element

(46) 9 Helical spring (according to the prior art)

(47) 10 Air-dryer cartridge

(48) 11 First outer coil

(49) 12 Inner coils

(50) 13 Second outer coil

(51) 14 Flange

(52) 15 Inlet opening

(53) 16 Outlet opening

(54) 17 Base plate

(55) 18 Bayonet protrusion

(56) 20 Cover

(57) 22 First connection element on 20

(58) 24 Second connection element on 2

(59) 31 Inner guide element, in particular mandrel

(60) 32 Outer guide element

(61) 34 Air-flow openings

(62) 91 Ground ends of 9