Housing and cover for friction damper of washing machine

Abstract

A shock absorber for a washing machine having a horizontal axis of rotation, comprising: a housing (2) in which a piston (3) slides; a friction ring (5) positioned inside the housing (2), surrounding the piston (3) and configured to exert a frictional effect on the piston upon relative movement between the piston and the housing; and a cover (4) provided with a central through-hole (46) into which the piston (3) is introduced, characterised in that the inner surface of the through-hole (46) comprises a plurality of longitudinal grooves (41) between which ribs (43) are interposed, said ribs (43) having a tapered profile from the outside to the center, said housing (2) comprising: a first portion (21), which is hollow inside, and a second portion (22), which is hollow inside and which is hollow inside; the cover (4) is accommodated in the first part by means of axial introduction; and a second portion (22) in which the piston (3) slides and in which a plurality of circumferential grooves (211) are provided, and the cover (4) comprises: an abutment surface (44) configured to abut a corresponding abutment surface (25) of the housing (2); and a portion (45) configured to be introduced into the internally hollow first portion (21) of the housing (2).

Description

[0001] The object of the present invention is a friction damper for a washing machine, which is provided with an optimized housing and a closed cover. Technical Field

[0002] It is known to use vibration dampers in washing machines. A vibration damper is a device fixed to the drum and frame of a washing machine to reduce the noise and vibration caused by the centrifugation of an electric washing machine.

[0003] All known embodiments comprise a generally tubular housing (or casing) open at one end and a piston sliding inside the housing, one of the housing and the piston being fixed to the frame of the washing machine and the other to the drum of the washing machine.

[0004] Furthermore, the damper comprises one or more friction rings, located between the sliding piston and the housing, and configured to damp the alternating vibrations of the piston caused by the rotation of the washing machine drum relative to the frame. According to the embodiment, these friction rings can be positioned in a cage sliding both towards the piston and the housing, mounted inside the housing but outside the piston, or they can be fixed, inserted in a suitable housing obtained in the inner wall of the housing.

[0005] The shock absorber also comprises a cover with a central through hole, which is arranged at the open end of the housing (in which the piston is inserted) to receive a friction ring which sometimes also has the function of guiding and lubricating the piston. Background Art

[0006] In the prior art, various embodiments of friction dampers for washing machines are known, the working principle of which is basically the same as that described above. EP1584730 describes a friction damper for a washing machine, which is provided with a closing cover with an elastic tongue. A variant scheme is described in EP1637640, in which a damper is described, whose cover includes internal teeth, which serve as a stop for a retaining frame, and a friction ring is arranged inside the retaining frame. A damper for a washing machine is described in EP3809010, in which the cover and the housing are assembled together by axial movement after being precisely positioned relative to each other. A similar embodiment is described in DE202016102547, which means that it also requires the housing to be precisely positioned to the cover. Slightly different covers from those just cited are described in EP1754908 and EP2406519.

[0007] US2017 / 292215 describes a friction damper for a washing machine, comprising a housing, a piston, a cover and a damping element.

[0008] The cover shown in US2017 / 292215 (referenced in FIG. 15 for ease of reading) comprises a plurality of bearing blocks for the sliding of the piston, which have a very limited axial extension relative to the axial extension of the cover and have a conical shape on the outside of the cover. In other words, the contact surface between the bearing blocks and the piston is subdivided into a small number of short and wide surfaces. This arrangement is not optimal for the lubrication of the connection between the piston and the cover, because it does not allow the grease to seal the free space between the cover hole and the piston during operation.

[0009] Furthermore, the cover just cited requires a precise angular positioning to the housing during the assembly step, since said cover has a series of hooks that must be assembled in corresponding holes provided on the housing.

[0010] In any case, other embodiments known in the prior art are also limited, in that in all cases, in order to assemble the cover to the housing, precise angular positioning is required, or a relative rotational movement between the cover and the housing is required. In addition, the durability of the lubrication of the relative sliding movement between the piston and the cover cannot be guaranteed.

[0011] However, in embodiments known in the prior art, the housing is provided with slits / elongated holes useful for accommodating corresponding cover teeth (or vice versa, the cover is provided with slits / elongated holes to accommodate corresponding teeth provided on the housing).

[0012] The arrangement of the teeth on the housing and the corresponding holes in the cover creates an inlet path for water, typically generated by condensation at the shock absorber, which can enter the outer shell of the friction strip, thereby soaking the friction strip and changing its friction characteristics, which in turn causes the shock absorber to operate outside the design conditions.

[0013] Purpose of the Invention

[0014] The object of the present invention is therefore to provide a shock absorber for a washing machine with a horizontal axis of rotation, which overcomes the limitations of the known embodiments of the prior art and in particular has a cover that can be assembled to the housing without requiring precise angular positioning and relative rotational movement between the cover and the housing, wherein the durability of the lubrication of the relative sliding movement between the piston and the cover is ensured.

[0015] According to another object, the invention provides a damper for a washing machine with a horizontal axis of rotation, in which damper there is no inlet path for water in the connection between the cover and the housing.

[0016] Brief Description

[0017] The present invention achieves the aforementioned objects by means of a shock absorber for a washing machine having a horizontal axis of rotation, the shock absorber comprising: a housing (2) in which a piston (3) slides; a friction ring (5) positioned inside the housing, surrounding the piston (3) and configured to exert a friction effect on the piston when relative movement occurs between the piston and the housing; and a cover (4) provided with a central through hole (46) into which the piston (3) is introduced, characterized in that the inner surface of the through hole (46) comprises a plurality of longitudinal grooves (41) between which ribs (43) are interposed, the ribs (43) being arranged to extend along the inner surface of the through hole (46) and extending along the inner surface of the through hole (46). 3) having a tapered profile from the outside to the center, the housing (2) comprising: an internally hollow first part (21), and a second part (22), the cover (4) being accommodated in the first part by axial introduction, the piston (3) sliding in the second part, and a plurality of circumferential grooves (211) being provided in the hollow first part (21), and the cover (4) comprising: an abutment surface (44), the abutment surface being configured to abut against a corresponding abutment surface (25) of the housing (2); and a part (45), the part being configured to be introduced into the internally hollow first part (21) of the housing (2). DETAILED DESCRIPTION

[0018] The following will refer to the attached Figures 1 to 14 Some preferred embodiments of the present invention are described in detail. Figures 1 to 3 Three assembled views showing a preferred embodiment of a shock absorber according to the invention; Figures 4 to 9 Various views showing a housing to be used with a shock absorber according to the invention; Figures 10 to 14 Various views are shown of a preferred embodiment of a cover to be used with a shock absorber according to the present invention.

[0019] like Figure 1 As shown, the device (1) comprises a housing (2) in which a piston (3) slides.

[0020] The housing (2) and the piston (3) are both provided with fastening rings (24, 34) for fixing to the frame and drum of a washing machine, in particular to a washing machine with a horizontal rotation axis.

[0021] like Figure 6 As shown, the housing (2) according to the present invention comprises: a first part (21) which is hollow inside and in which the cover (4) is installed by axial introduction; and a second part (22) in which the piston (3) slides.

[0022] In particular, the hollow first portion (21) is provided with a plurality of circumferential grooves (211).

[0023] Fig.11 and Fig.12 A cover (4) is shown, which is provided with an abutment surface (44) configured to abut against a corresponding abutment surface (25) of the housing (2), and the cover (4) is also provided with a portion (45) configured to be introduced into the first portion (21) of the hollow interior of the housing (2).

[0024] In particular, the portion (45) of the cover (4) configured to be introduced into the interior of the housing (2) comprises a plurality of circumferential ribs (42) configured to be interference fit with corresponding circumferential grooves (211) of the housing (2).

[0025] Thus, once the cover (4) has been axially introduced into the housing (2) until it is in abutment with its own surface (44), it can no longer be removed from its own seat.

[0026] The coupling of the housing (2) and the cover (4) is the first characteristic of the device (1) according to the invention which makes it superior to the devices known in the prior art; in fact, for the assembly of the cover (4), it is not necessary to follow any angular reference. The cover (4) is completely symmetrical about its own axis in terms of its outer geometry and can therefore be correctly assembled simply by an axial movement, whatever its own angle of rotation (no relative rotation between the cover and the housing is required during the assembly step).

[0027] For devices that require the cover to be screwed onto the housing (and therefore require relative rotational movement) and for devices that require a good determination of the angular position of the cover relative to the housing for assembly, this is obviously a very advantageous condition when organizing an automated production line.

[0028] The cover (4) also comprises a central through hole (46) into which the piston (3) can be introduced. The inner surface of the through hole (46) is provided with a plurality of longitudinal grooves (41), between which ribs (43) are inserted.

[0029] The rib (43) extends along the entire axial extension of the cover.

[0030] Preferably, the number of ribs (43) is greater than 12, more preferably 18 to 20.

[0031] The radial depth of the groove (41) is small compared to the dimensions of the cap, wherein the difference in radius between the recess of the groove (41) and the head of the rib (43) is preferably equal to about 1 / 20 of the diameter of the central hole of the cap (4).

[0032] The alternating appearance of grooves and ribs serves to optimize the lubrication of the piston (3) during sliding.

[0033] It is observed that, in fact, the piston (3) slides in the central hole of the cover, guided by the friction ring (5) made of polyurethane. Therefore, the device does not rely on the contact between the piston and the rib to guide the piston movement. The contact between the piston and the rib is occasional, which is related to the presence of temporary vibrations or stresses, but it is lubricated by the grease introduced during the assembly step, which is deposited in the longitudinal grooves (41) and also forms a lubricating veil on the top of the rib (43). Fig.14 As shown, the rib (43) has a tapered profile from the outside towards the center. The base (431) of the rib (43) is larger than the head (432) of the rib, and the cross-section of the rib is such that there is no gap underneath the rib itself.

[0034] As a result, the grease never gets underneath the ribs and is fully available for improved lubrication.

[0035] Furthermore, the fact that the number of ribs is high and the grooves have a limited depth allows the grease introduced during the lubrication step to substantially seal the free space between the cover and the piston, thus preventing dirt and moisture from penetrating into the interior of the housing.

[0036] During the operating steps, the relative movement between the piston (3) and the housing (2) and the vibrations to which the device (1) is inevitably subjected cause the grease accumulated in the longitudinal grooves to be distributed in a substantially uniform manner over the surface of the piston.

[0037] In particular, the grooves act as distributed reservoirs for lubricant.

[0038] It is observed that in the case of the embodiment shown, there is no need to provide an elongated hole for the hook coupling, and the cover closed on the housing is sealed. Therefore, there is no possibility of water entering the housing to damage the friction ring and impair the performance of the grease.

[0039] This fact significantly prolongs the life of the device according to the invention compared to the devices known from the prior art.

Claims

1. A shock absorber for a washing machine having a horizontal rotation axis, the shock absorber comprising: A housing (2) in which a piston (3) slides; a friction ring (5) positioned inside the housing (2), surrounding the piston (3) and configured to exert a friction effect on the piston when relative movement occurs between the piston and the housing; and a cover (4) provided with a central through hole (46) in which the piston (3) is introduced. Features - the inner surface of the through hole (46) comprises a plurality of longitudinal grooves (41), between which ribs (43) are inserted, the ribs (43) having a tapering profile from the outside towards the center, The housing (2) comprises: a first part (21) which is hollow inside and in which the cover (4) is accommodated by axial introduction; and a second part (22) in which the piston (3) slides, And among them - the first hollow portion (21) is provided with a plurality of circumferential grooves (211), and The cover (4) comprises: an abutment surface (44) configured to abut against a corresponding abutment surface (25) of the shell (2); and a portion (45) configured to be introduced into the first hollow portion (21) inside the shell (2), and the portion is provided with a plurality of circumferential ribs (42) configured to be connected to the circumferential groove (211).

2. The shock absorber for a washing machine having a horizontal rotation axis according to claim 1, characterized in that The rib (43) extends along the entire axial extension of the cover.

3. A shock absorber for a washing machine having a horizontal rotation axis according to claim 1 or 2, characterized in that: The number of the ribs (43) is greater than twelve.

4. The shock absorber for a washing machine having a horizontal rotation axis according to claim 3, characterized in that The number of the ribs (43) is between 18 and 20.

5. Shock absorber for a washing machine with a horizontal axis of rotation according to any one of the preceding claims, characterized in that The difference in radius between the recess of the longitudinal groove (41) and the head of the rib (43) is between 2.5% and 10% of the diameter of the central hole of the cover (4).

6. The shock absorber for a washing machine having a horizontal rotation axis according to claim 5, characterized in that The difference in radius between the recess of the longitudinal groove (41) and the head of the rib (43) is equal to about 1 / 20 of the diameter of the central hole of the cover (4).

7. Shock absorber for a washing machine with a horizontal axis of rotation according to any one of the preceding claims, characterized in that The rib (43) has a tapered profile from the outside towards the center, wherein the size of the base (431) of the rib (43) is greater than the size of the head (432) of the rib, and the shape of the cross-section of the rib (43) is such that there is no gap arranged under the rib itself.

8. The shock absorber for a washing machine having a horizontal rotation axis according to claim 1, characterized in that The portion (45) of the cover (4) configured to be introduced into the housing (2) comprises a plurality of circumferential ribs (42).

9. Shock absorber for a washing machine with a horizontal axis of rotation according to any one of the preceding claims, characterized in that The circumferential rib is configured to be interference-fitted with a corresponding circumferential groove (211) provided on the inner surface of the first hollow portion (21) of the housing (2), so that once the cover (4) is axially introduced into the housing (2) until it abuts against the surface (44) of the cover itself, the cover can no longer be removed from its seat.

10. Shock absorber for a washing machine with a horizontal axis of rotation according to any one of the preceding claims, characterized in that The housing (2) and the piston (3) are both provided with fastening rings (24, 34) for fastening to the frame and drum of a washing machine.

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