SWITCHABLE DAMPER

Abstract

A switchable damper comprises a housing having a longitudinal axis, a plunger displaceable along the longitudinal axis, a piston arranged between the housing and the plunger, a friction lining arranged on the piston and a switching unit, which is switchable between a blocking arrangement, in which the piston is blocked with respect to a displacement along the longitudinal axis, and a free-moving arrangement, in which the piston is released with respect to a displacement along the longitudinal axis.

Claims

1. A switchable damper (1; 1a; 1b) comprising a. a housing (2; 2a; 2b) having a longitudinal axis (3), b. a plunger (4) displaceable along the longitudinal axis (3), c. a piston (20) arranged between the housing (2; 2a; 2b) and the plunger (4), d. a friction lining (21) arranged on the piston (20), e. a switching unit (23; 23a; 23b) which is switchable between a blocking arrangement, in which the piston (20) is blocked with respect to a displacement along the longitudinal axis (3), and a free-moving arrangement, in which the piston (20) is released with respect to a displacement along the longitudinal axis (3).

2. A switchable damper according to claim 1, wherein the friction lining (21) is arranged radially to the longitudinal axis (3) between at least one of the plunger (4) and the piston (20) and between the piston (20) and the housing (2; 2a; 2b).

3. A switchable damper according to claim 1, wherein the switching unit (23; 23a; 23b) has a switching actuator (28; 28a 28b) to switch between the blocking arrangement and the free-moving arrangement.

4. A switchable damper according to claim 3, wherein the switching actuator (28; 28a 28b) has a switching drive (24; 24a; 24b) and an adjusting element (31; 31b).

5. A switchable damper according to claim 3, wherein the adjusting element (31; 31b) is arranged concentrically to the longitudinal axis (3), wherein activating the switching drive (24; 24a; 24b) causes the adjusting element (31; 31b) to rotate about the longitudinal axis (3).

6. A switchable damper according to claim 3, wherein the switching drive is designed as a switchable stroke magnet (24).

7. A switchable damper according to claim 6, wherein said switchable stroke magnet (24) is connected by means of a force transmission element (26) to a rotatable adjusting ring (27).

8. A switchable damper according to claim 6, wherein the force transmission element (26) is designed to be flexible.

9. A switchable damper according to claim 8, wherein the switching unit (24) has a safety unit.

10. A switchable damper according to claim 9, wherein the safety unit comprises power storage elements.

11. A switchable damper according to claim 9, wherein the power storage elements are configured as at least one of a spring element (29) arranged between the force transmission element (26) and the adjusting ring (27) and a condenser in the stroke magnet.

12. A switchable damper according to claim 6, wherein the switching drive is a switchable electric motor (24a), wherein the adjusting element (31) is driveable by means of a gear wheel (36).

13. A switchable damper according to claim 6, wherein the switching drive is a switchable rotary magnet (24b), wherein the adjusting element (31b) is coupled directly to the rotary magnet (24b).

14. A switchable damper according to claim 6, wherein the adjusting element (31; 31b) has the shape of a sleeve.

15. A switchable damper according to claim 14, wherein the adjusting element (31; 31b) has at least one torque transmission element (32; 32b).

16. A switchable damper according to claim 6, wherein the switching unit (23; 23a; 23b) has a shaped element (33) which is engageable with a mating shaped element (34) in the blocking arrangement.

17. A switchable damper according to claim 16, wherein the shaped element (33) is a radial pin which is engageable in the mating shaped element (34) designed on a shaped gate.

18. A switchable damper according to claim 17, wherein the mating shaped element (34) is arranged on the piston (20).

19. A switchable damper according to claim 17, wherein the shaped element (33) is arranged on the adjusting element (31; 31b).

20. A switchable damper according to claim 1, comprising an impact damping unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a perspective illustration of a switchable damper according to the invention in a first embodiment example,

[0024] FIG. 2 shows a longitudinal section through section line II-II in FIG. 1,

[0025] FIG. 3 shows a perspective illustration of the adjusting element of the damper in FIGS. 1 and 2,

[0026] FIG. 4 shows a perspective illustration of the piston of the damper according to FIGS. 1 and 2,

[0027] FIG. 5 shows a perspective illustration of a partial section of the piston and of the adjusting element in a blocking arrangement,

[0028] FIG. 6 shows a perspective illustration of a switching actuator of the damper according to FIGS. 1 and 2,

[0029] FIG. 7 shows a perspective illustration of a partially cutaway section of the damper according to FIG. 1 in the blocking arrangement,

[0030] FIG. 8 shows an illustration according to FIG. 7 of the damper in the free-moving state,

[0031] FIG. 9 shows an illustration according to FIG. 1 of a damper according to a second design example,

[0032] FIG. 10 shows a perspective illustration of the switching actuator of the damper according to FIG. 9,

[0033] FIG. 11 shows an illustration according to FIG. 1 of a damper according to a third design example and

[0034] FIG. 12 shows a perspective illustration of the switching actuator of the damper in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A switchable damper designated as 1 throughout in FIGS. 1 to 8 can be used in a washing machine to dampen an imbalance of the washing drum.

[0035] The damper 1 comprises a substantially cylindrical housing 2 with a longitudinal axis 3. A substantially tube-shaped plunger 4 is arranged concentric to the longitudinal axis 3, and can be displaced along the longitudinal axis 3 relative to the housing 2. The plunger 4 can also have a full cross section. The plunger 4 is arranged with a first end inside the housing 2 and with a second end leading out of the housing 2. On the second end away from the housing 2, the plunger 4 has a plunger fastening element 5. The plunger fastening element 5 has a through-sleeve 6 whose sleeve axis is orientated perpendicular to the longitudinal axis 3.

[0036] The housing has a housing fastening element 7 at one end of the damper 1 opposite the plunger fastening element 5, wherein said housing fastening element is designed to be substantially identical to the plunger fastening element 5 and has a sleeve 6. The plunger fastening element 5 is attached solidly to the plunger 4. The housing fastening element 7 is attached solidly to the housing 2. The housing fastening element 7 is fastened in particular to an end face of a guide section 19 of the housing 2.

[0037] The damper 1 is arranged with the fastening elements 5, 7 in the washing machine, in particular between its frame and the washing drum, in order to dampen a movement of the washing drum, in particular due to an imbalance during rotation, with respect to the frame.

[0038] The housing 2 is made in a plurality of parts and comprises a switching housing portion 8 shown on the right in FIG. 2 and a friction damping housing portion 9 attached detachably to it. The switching housing portion 8 and the friction damping housing portion 9 are arranged one behind the other along the longitudinal axis 3. The switching housing portion 8 is attached to the friction damping housing portion 9 at the end face away from the housing fastening element 7. The attachment can be implemented by snap-in elements 10 corresponding to each other.

[0039] The friction damping housing portion 9 is closed by means of a guide cap 11 on the end of the housing 2 towards the plunger fastening element 5. The guide cap 11 has a central guide opening 12, through which the plunger 4 is guided into an inner chamber of the housing 4. The guide cap 11 has at least one positioning tab 13 extending along the longitudinal axis 3, wherein said positioning tab engages in a recess 14 provided for it on the housing 2, in particular the friction damping housing portion 9. The positioning tab 13 enables the rotary position of the guide cap 11 to be established uniquely relative to the housing 2. The positioning tab 13 also serves to prevent the guide cap 11 from rotating about the longitudinal axis 3 relative to the housing 2.

[0040] Four cap free-running stops 16 are formed as one part on the guide cap 11 on an inner side of the end face 15. The cap free-running stops 16 are orientated parallel to the longitudinal axis 2 and are arranged in the shape of circular segments around the plunger 4 in a plane perpendicular to the longitudinal axis 3. The guide cap 11 is produced, in particular, from an elastic material, in particular from plastic. More or fewer than four cap free-running stops 16 can be provided. The cap free-running stops 16 are arranged spaced apart from each other in a tangential direction in relation to the longitudinal axis 3, in particular spaced apart equally. An open space is provided between two adjacent cap free-running stops 16.

[0041] A housing base 17 is formed as one part on the end face of the friction damping housing portion 9 opposite the guide cap 11. The housing base 17 is orientated perpendicular to the longitudinal axis 3. Four base free-running stops 18, for example, extend out from the housing base 17 towards the guide cap 11. Each of the base free-running stops 18 is orientated parallel to the longitudinal axis 3 and is designed to correspond with the cap free-running stops 16. The guide section 19 is formed as one part on the housing base 17 away from the base free-running stops 18. The guide section 19 serves to guide the plunger 4 when it is displaced axially inside the housing 2. The internal diameter of the guide section 19 corresponds substantially to the external geometry of the plunger 4. At the end opposite the plunger 4, the housing fastening element 7 is arranged on the guide section 19. The guide section 19 is guided through the switching housing portion 8 and the housing fastening element 7 projects beyond the rear end of the housing 2, shown on the right in FIGS. 1 and 2.

[0042] A piston 20 is arranged in the housing 2, in particular in the friction damping housing portion 9. The piston 20 is designed substantially as a hollow cylinder. The piston 20 can be displaced along the longitudinal axis 3 in the housing 2 and relative to the plunger 4. The piston 20 is arranged between the plunger 4 and the housing 2 in the radial direction of the longitudinal axis 3.

[0043] The piston 20 has an inner annular groove in which a friction lining 21 is arranged. The friction lining 21 is guided by the piston 20 where it is accommodated. A movement of the piston 20 along the longitudinal axis 3 causes the friction lining 21 to be displaced. The friction lining 21 is designed, in particular, as friction strips whose front faces can be made even or uneven, for example, jagged or wavy or in some other type of profile. The internal cylindrical friction surface of the annular friction lining 21 is in contact with an external side of the plunger 4. A relative movement between the plunger 4 and the friction lining 21 results in a frictional force acting against the movement, in other words it causes frictional damping.

[0044] The internal groove of the piston 20 is delimited on both sides in the axial direction by guide ribs 22. The guide ribs 22 are designed integrally with the piston 20. The guide ribs 22, with respect to the internal groove, project radially inwards relative to the longitudinal axis 3. The guide ribs 22 are each made in the shape of annular segments in a plane perpendicular to the longitudinal axis 3. The internal contour defined by the guide ribs 22 corresponds substantially to the external contour of the plunger 4, wherein the internal contour in the area of the guide ribs 22 is larger than the external contour of the plunger 4 to the extent that it is not possible for the piston 20 to come into direct contact with the plunger 4.

[0045] Four guide ribs 22 are provided respectively at the end faces of the piston 20. Regarding their tangential extension, the guide ribs 22 are designed around the longitudinal axis 3 such that they can engage in the intermediate spaces between the longitudinal cap ribs 16 or, respectively, in the intermediate spaces between the longitudinal base ribs 18. According the illustration of the damper in FIG. 2, the piston 20 is arranged adjacent to the guide cap 11. The guide ribs 22 which face the guide cap 11, engage in the intermediate spaces between adjacent longitudinal cap ribs 16. As a result, the piston 20 cannot rotate relative to the housing 2 unintentionally. Regarding their tangential position, the four longitudinal cap ribs 16 are arranged so that they are rotated through 45° relative to the longitudinal base ribs 18. The friction lining 21 in the piston 20 is located free to move in the axial direction of the longitudinal axis 3 at least locally through the intermediate spaces between two guide ribs 22. This area where the friction lining 21 is free to move can be restricted by the end faces of longitudinal cap ribs 16 or longitudinal base ribs 18. The friction lining 21 serves as a stop buffer.

[0046] The damper 1 also has a switching unit 23 which enables switching between a blocking arrangement and a free-moving arrangement of the piston 20. The switching unit 23 comprises a switching actuator 28 with a switching drive 24. According to the design example shown, the switching drive 24 is designed as a stroke magnet which causes a linear stroke movement and is triggered by electrical switching.

[0047] The stroke magnet is fitted on the housing 2 of the damper 1 such that the linear stroke axis 25 is orientated parallel to the longitudinal axis 3 of the damper. In the area of the switching housing portion 8, in which the stroke magnet is arranged, the housing 2 is non-round, that is, it is designed so that it deviates from a cylindrical shape. The stroke magnet is connected to an adjusting ring 27 by means of a force transmission element 26. The switching drive 24 as a switchable stroke magnet, the force transmission element 26 and the adjusting ring 27 form the switching actuator 28, which is illustrated in FIG. 6. The force transmission element 26 is designed as a flexible wire which is guided, in particular, along a rigid guide channel The force transmission element engages, in particular, substantially radially with the adjusting ring 27 and can be displaced there against a spring force provided by an energy storage element in the form of a spring element 29. The adjusting ring 27 has two openings 30, arranged eccentrically to the longitudinal axis 3, in which a sleeve-shaped adjusting element 31 with engagement tab on the face 32 engages. The adjusting element 31 is a component part of the switching unit 23. The switching unit 23, in particular in the form of the adjusting element 31, enables a positive connection to be made with the piston 20 in the blocking arrangement and the piston 20 to be released in the free-moving arrangement. For this, the adjusting element 31 has a radial pin as a shaped element 33 on an inner side of the inner cylinder cover face which can engage with a mating shaped element 32 on a shaped gate. The mating shaped elements 32 are formed integrally on an outer side of the substantially cylindrically designed piston 20. According to the design example shown, two shaped gates are provided on the piston 20 wherein each shaped gate has two mating shaped elements 34. The mating shaped elements 34 are each designed to be substantially U-shaped wherein the parallel legs of the U extend in a circumferential direction about the longitudinal axis 3 in the installed condition of the piston 20. The shaped gates are arranged diametrically opposite on the outer side of the piston 20 relative to the longitudinal axis 3. Each opening of the U is orientated in a circumferential direction about the longitudinal axis 3.

[0048] The function of the friction damper 1 is explained in more detail below. According to the arrangement of the adjusting element 31, as shown in FIG. 7, the damper 1 is positioned in the blocking arrangement. In the blocking arrangement, the shaped element 33 is located in one of the mating shaped elements 34. The parallel legs of the U of the mating shaped elements 34 form an undercut in a direction parallel to the longitudinal axis 3. A displacement of the piston 20 relative to the housing 2 and/or to the plunger 4 is blocked. A displacement of the plunger 4 relative to the housing 2 causes a friction force on the plunger 4 due to the friction lining 21 bearing on it radially and blocking it axially. In this arrangement, the friction damping function of the damper 1 is switched on, that is, activated.

[0049] In order to switch the damper 1 over to the free-moving arrangement, the switching unit 23 is activated by operating the switching actuator 28. By switching on the stroke magnet 24, the force transmission element 26 which engages with the stroke magnet 24 is displaced along the stroke axis 25. The force transmission element 26 is driven radially along the curved guide channel to the adjusting ring 27. The force transmission element 26 exerts a torque on the adjusting ring 27 about the longitudinal axis 3 and causes the adjusting ring 27 to rotate about the longitudinal axis 3. Together with the adjusting ring 27, the adjusting element 31 is rotated which is retained with the engagement tabs 32 in the openings 30 of the adjusting ring 27. Due to the rotation of the adjusting element 31, the shaped element 33 is rotated relative to the piston 20, the plunger 4 and the housing 2 about the longitudinal axis 3. The shaped element 33 is displaced out of the mating shaped element 34. The free-moving arrangement of the damper is shown in FIG. 8. In the free-moving arrangement of the mating shaped element 34, the shaped element 33 is arranged offset in a circumferential direction, that is, in a tangential direction, with respect to the longitudinal axis 3. The piston 20 is released by the adjusting element 31. In the free-moving arrangement, the piston 20 can be displaced along the longitudinal axis 3 relative to the housing 2 and relative to the plunger 4.

[0050] In order to transfer the damper 1 back to the blocking arrangement, the stroke magnet 24 is switched in the correspondingly opposite direction, thereby rotating the adjusting element 31 in the opposite direction about the longitudinal axis 3.

[0051] The spring element 29 is a part of a safety device which enables the switching unit 23 to be switched again in the event of a power failure. For this, a condenser (not shown) is provided which can store electrical energy which is sufficient to switch the stroke magnet 24 if the power supply is interrupted. The movement of the stroke magnet 24 is stored mechanically in the spring element 29.

[0052] Both mating shaped elements 34 of a shaped gate are arranged with a gap between each other along the longitudinal axis 3. It is possible, thereby, that the piston 20 can be blocked in different positions by means of the adjusting element 31 and its shaped element 33 along the longitudinal axis 3. In particular, lead-in chamfers can be provided on the mating shaped element 34 along the rotary direction of the adjusting element 31 to make it easier to guide the shaped element 33 into the mating shaped element 34 if the positioning of the shaped element 33 in relation to the mating shaped element 34 is imprecise, that is, if the positioning does not line up precisely.

[0053] Other embodiments for the shaped element 33 and the mating shaped element 34 are conceivable. According to a design (not shown), the shaped element can be designed in the shape, for example, of a wedge which, by means of its wedge tip, is able to engage by locking into a plurality of, in particular many, sharp recesses made on a shaped gate corresponding to the wedge tip. In particular at least five, in particular at least 10 and in particular at least 20 corresponding recesses, into which the wedge tip can engage, can be provided on the shaped gate. It is possible, thereby, that the shaped element can engage in one of the mating shaped elements substantially independently of the axial positioning of the piston 20.

[0054] The friction lining 21 can also be arranged on an outer side of the piston 20. In this case, the mating shaped element is positioned on an inner side of the piston 20. The shaped element would then be arranged between the plunger 4 and the piston 20.

[0055] Below, and referring to FIGS. 9 and 10, a second design example of the invention is described. Structurally identical parts have the same reference symbols as in the first design example, whose description is hereby referred to. Structurally different though functionally identical parts have the same reference symbols with an ‘a’ placed after.

[0056] The essential difference compared with the first design example consists in the embodiment of the switching unit 23a. The switching unit 23a, in particular the switching actuator 28a, has, as a switching drive 24a, a switchable rotary magnet, which is also known as a plunger coil or voice coil. The rotary magnet enables an active component to rotate relative to a static, passive component. The active component of the rotary magnet is coupled in a torque-proof manner by means of the engagement tabs 32 of the adjusting element 31 by the method described above. In order that the rotary magnet 24a is arranged concentrically to the longitudinal axis 3, the housing 2a, in particular the switching housing portion 8a, is designed substantially as a cylinder. The structural size of the housing 2a, in particular the length of the housing along the longitudinal axis 3 of the switching housing portion 8a, is reduced. The damper 1a is structurally particularly compact.

[0057] Below, and referring to FIGS. 11 and 12, a third design example of the invention is described. Structurally identical parts have the same reference symbols as in the first two design examples, whose description is hereby referred to. Structurally different though functionally identical parts have the same reference symbols with a ‘b’ placed after.

[0058] The essential difference compared with the previous design examples consists, in the case of the damper 1b, in the embodiment of the switching unit 23b, which has a switchable motor, in the form, for example, of an electric motor, as a switching drive 24b. A gear wheel 36 is provided on the output shaft 35 of the electric motor 23b. The electric motor 24b is arranged on the housing 2b of the damper 1b such that the rotary axis 37 of the electric motor 24b is arranged parallel to the longitudinal axis 3 and offset from the longitudinal axis 3. The gear wheel 36 engages with its external teeth in corresponding external teeth 32b on the adjusting element 31b. The external teeth 32b correspond to the engagement tabs on the adjusting elements according to the previous design examples. The engagement tabs 32 and the external teeth 32b also serve as torque transmitting means to transfer the switching torque produced by the switching actuator 28, 28a, 28b to the sleeve-shaped adjusting element 31, 31b and to make the adjusting element 31, 31b rotate about the longitudinal axis 3 of the housing 2.