GB2255600A

GB2255600A - A shock-absorber for washing machines

Info

Publication number: GB2255600A
Application number: GB9209699A
Authority: GB
Inventors: Piero Durazzani
Original assignee: Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1991-05-08
Filing date: 1992-05-06
Publication date: 1992-11-11
Also published as: ITPN910014V0; GB9209699D0; FR2676238A1; IT225645Y1; ES1021129U; FR2676238B3; ITPN910014U1; ES1021129Y; DE9206047U1

Abstract

A shock-absorber for washing machines, particularly washing machines or combined washing and drying machines for laundry, is adapted to damp the vibrations of the tank-drum unit which occur during the washing cycles. The shock-absorber includes a tubular metal casing (4, Fig. 2) and a rod 9 which can slide to and fro therein, the free ends of the casing (4) and the rod 9 being connected, respectively, to the base of the housing of the machine and to the lower portion of the washing tank. The rod 9 has a plurality of annular braking elements 12 of antifriction material which act by friction against the inner surface of the tubular casing (4) to damp the vibrations, and each of which has a through-hole 14 the diameter of which is larger than the outside diameter of its seat 13 so as to leave a clearance. <IMAGE>

Description

The invention relates to a shock-absorber for washing machines, which is mounted between the base of such a machine and the washing tank containing the rotary drum and is formed so as effectively to damp the vibrations which occur in the tank-drum unit as it rotates at the washing and spinning speeds during each selected washing cycle.

Shock-absorbers for the purpose specified above, for washing machines, particularly washing machines or combined washing and drying machines for laundry, are known, which include essentially a tubular metal casing and a rod which can slide to and fro therein, the free ends of the casing and the rod generally having eyes and being connected, respectively, to the base of the washing machine and to the lower portion of the tank containing the rotary drum, by known fixing means.

One known solution, in particular, provides for the use of a series of annular braking elements of conventional, resilient antifriction material which are spaced apart axially and can be fitted in corresponding seats on the rod, each braking element having a central hole with a diameter such that it can slip over the outside diameter of the rod into its seat with minimal interference and a peripheral surface having a diameter such that it can be inserted in the cavity in the tubular casing, also with minimal interference, so that it damps the vibrations of the tank-drum unit during its operation at the washing and spinning speeds during respective washing cycles as a result of the reciprocating movement of the rod in the cavity of the tubular casing, by means of the friction between the peripheral surfaces of the braking elements on the rod and the inner cylindrical surface of the tubular casing.

This type of shock-absorber thus requires extremely accurate dimensional tolerances for the inside diameter of the hole and the diameter of the peripheral surface of each braking element so that it can be fixed in position without being deformed and, moreover, to ensure the correct friction with the inner cylindrical surface of the tubular casing so that the damping effect on the vibrations of the tank-drum unit is always the same.In practice, however, these conditions are difficult to achieve, given that, when each braking element is fitted in position, because of the interference described above, it is necessary to stretch it slightly beforehand, making use of the resilience of its material, in order to make the inside diameter of the element fit its seat on the rod precisely, and this operation involves a risk of breakage or deformation of the braking element which may adversely affect its ability to function correctly so that it achieves an unsatisfactory braking effect.

The object of the present invention is to eliminate this problem by means of a shock-absorber for washing machines having the structural characteristics described essentially with particular reference to the claims appended to the present patent.

The invention will be understood better from the following description which is given solely by way of non-limiting example, with reference to the appended drawings, in which: Figs. 1 and 2 are partially-sectioned front views of the rod of the present shock-absorber and of the fully assembled shock-absorber, respectively.

With reference to the drawings, a shock-absorber 3 according to the invention is shown schematically, mounted between the lower portion of the washing tank (not shown) containing the rotary drum and the base of the housing (also not shown) of a washing machine, particularly a washing machine or a combined washing and drying machine for laundry, in order to damp the vibrations of the tank-drum unit which occur when the drum is operating at its washing and spinning speeds during each selected washing cycle.The shock-absorber includes, essentially, an elongate tubular metal casing 4 which is set in a support structure 5 of plastics material having an open end 6 and a closed end 7 with an integral eye 8 which is adapted to be fixed to the base of the housing of the washing machine by a pin (not shown), as well as a rod 9 of plastics material, of which one end can be inserted in the cylindrical cavity 10 of the tubular casing in order to perform the functions described below and the other end has an eye 11 for fixing to the lower portion of the washing tank of the washing machine by a pin (not shown).

This type of shock-absorber is substantially identical to that described in Italian patent application No.

34061-B/87 filed on 4-11-1987 in the name of Industrie Zanussi S.p.A., to which reference should therefore be made for a better understanding of the structural characteristics of the shock-absorber.

Like the solution protected by that patent application, the present shock-absorber also includes a plurality of annular braking elements 12 of conventional, resilient antifriction material which are housed in corresponding seats 13 spaced axially along the periphery of the rod 9, near its free end.

The purpose of the braking elements 12 is to achieve uniform and continuous braking of the vibrations of the tank-drum unit during the washing cycles so as to damp them effectively by means of the friction caused by the rubbing of the peripheral surfaces of the elements against the inner cylindrical surface of the tubular casing 4 during the reciprocating movement of the rod 9 in the cavity 14 of the tubular casing as a result of the vibrations. In particular, each braking element 12 is formed conventionally with a central through-hole 14 so that it can be slipped over the periphery of the rod 9 into its seat 13, the diameter of the hole being larger than the corresponding outside diameter of the rod so as to leave a clearance X, as can be seen in Figure 1 in particular.

Moreover, the outside diameter of the peripheral surface of the braking element 12 is such that it fits perfectly against the corresponding inner cylindrical surface of the tubular casing 4 when the braking element is inside the tubular casing, thus achieving the predetermined braking effect in the manner specified above.

By virtue of the clearance X, each braking element 12 can thus simply be fitted in its seat 13 on the rod 9 without the need to be stretched, as was previously necessary, so that any breakage or deformation of the element is prevented.

As can be seen in Figure 2, which shows the tubular casing 4 and the rod 9 of the present shock-absorber in the assembled condition, each braking element 12 can be set in position by virtue of the clearance X and, because its dimensions remain unchanged since it is no longer stretched, it always ensures the correct braking by friction with the inner surface of the tubular casing 4.

Claims

CLAIM

A shock-absorber for washing machines, particularly washing machines or combined washing and drying machines for laundry, including a tubular casing and a rod which can slide to and fro therein, the free ends of the casing and the rod being articulated, respectively, to the base of the housing of the machine and to the lower portion of the washing tank containing the rotary drum for the laundry, the rod having a plurality of annular braking elements of conventional, resilient antifriction material which are housed in corresponding seats spaced axially along the periphery of the rod and are adapted to achieve a braking effect in order to damp the vibrations of the tank-drum unit during the respective washing cycles of the machine by virtue of the friction caused by the rubbing of their peripheral surfaces against the corresponding inner surface of the tubular casing, the shock-absorber being characterised in that the diameter of the central through-hole (14) in each braking element (12) is larger than the outside diameter of its seat (13) on the rod (9) so as to leave a clearance (X).