BG98921U - Friction shock-absorber - Google Patents

Abstract

The friction shock-absorber finds application for damping the maximum oscillations of elastically suspended objects such as washing machines, motor-cars and trailers. It achieves automatic offsetting of the wear of the friction elements by adjusting the friction force. The friction shock-absorber consists of a housing, in the form of thin-wall plastic cylinder (1) having a designed extension in which specially shaped three polyamide shell-sectors (3) each of 120°C are housed concentrically. The shells are pressed to an axially positioned cylindrical steel rod (2) by two conical bushings (4 & 5) and two cylindrical screw springs (6 & 7) , folded in advance, and axially fitted between the conical bushing and the housing of the shock-absorber, the deformation of the springs can additionally be adjusted by supporting washers (9). The housing of the shock-absorber has a lug machined to be locked to a fixed base, and the rod has also a lug for fitting to the oscilation object.\!

Description

Technical field

The utility model refers to a friction damper applicable to

reducing machines at maximum spin speeds. It may be the vibrations of other elastically-mounted trailers.

of automatic washing machines and extinguishing of objects such as cars and

Background

A friction shock absorber [1] is known to reduce the vibration of washing machines by spinning, in which a piston is mounted in a thin-walled metal cylinder, on which a rigid polyurethane sleeve is fastened. The friction force is obtained by sliding the sleeve into the cylinder, between which there is pressure due to the larger outer diameter of the sleeve relative to the inner diameter of the cylinder.

The disadvantage of this friction damper is that, with prolonged operation, the friction force decreases significantly due to the wear of the friction element. A disadvantage of the construction is the inability to adjust the friction force.

Technical nature

The task of the utility model is to create a friction damper in which the wear of the friction element is automatically compensated so that the friction force remains constant during prolonged operation, with the magnitude of

The task is to extend one end of the extension, in three polyamide shells and in the friction force, to adjust.

solves by means of a friction damper, on a thin-walled plastic cylinder, which is concentrically placed separately sectors of 120 degrees. The shells which are molded are pressed from the outside inwards to an axially arranged cylindrical metal rod by two conical bushings and two pre-bent cylindrical screw springs placed axially between the conical bushings and the shock absorber housing. The damper housing has a molded ear for attachment to a fixed base, and the stem has a molded ear for attachment to the vibrating object.

The benefits of the friction damper according to the utility model are:

- the wear of the friction elements is automatically compensated by the pressure of the springs;

- by changing the stiffness and the pre-deformation of the springs, it is possible to adjust the maximum friction force in a certain range, depending on the parameters of the shock absorber;

- by changing the angle of the pressure cones, the stiffness of the springs and the number of springs (one or two), it is possible to obtain different characteristics of the shock absorber;

-with small oscillation amplitudes (up to 3-4 mm), the shock absorber acts as an elastic element, the shells being relatively stationary to the stem, which in turn reduces the wear of the friction elements.

-the damper is repairable.

Example of implementation

The utility model is illustrated by an exemplary embodiment shown in the accompanying figures, of which:

Figure 1 is a longitudinal section of the shock absorber; Figures 2, 3 and 4 show the possible characteristics of the shock absorber.

The friction damper of FIG. 1 has a cylindrical thin-walled plastic housing 1, to one end of which there is a molded ear for attachment to a fixed base, and at the other end there is a widening to accommodate the friction members. An axial metal rod 2 moves freely through the housing 1, passing freely through a cap 8 closing the other end of the housing. There is a shaped ear towards the outer end of the cheek that secures the shock absorber to the vibrating object. The housing is housed in three sections, 120-degree polyamide sleeve 3, which is pressed against the stem of two conical bushings 4 and 5 by means of two cylindrical screw springs 6 and 7, wherein the springs are pre-deformed, which may further adjust by means of washers 9.

Shock absorber action

The action of the friction damper is as follows:

In the static position, the spacer sleeve 3 is pressed against the spacer 2 by means of conical bushings 4 and 5 and the springs b7. pressure and the coefficient of friction between the bushing material and the stock material. This friction force always reverses the direction of movement of the stem, thus preventing the movement of the vibrating object.

Possible characteristics of the shock absorber are shown in Fig. 3 and Fig. 4, where it is indicated:

figure 2,

F - the tensile force of the shock absorber

X - move the cheek against the housing

T - friction force δ - elasticity interval c - spring stiffness

Figure 2 shows the characteristic of the damper when the rigidities of the two springs are the same. In this case, the shock absorber has a symmetrical stretching and contraction characteristic.

Figure 3 shows the characteristic of the damper when the stiffness of the springs is different, and in particular when the stiffness of spring b (outer) is greater than the stiffness of spring 7 (inner). In this case, the friction force of the shock absorber is greater than the friction force of the shock absorber.

Figure 4 shows the performance of the shock absorber when the outer spring (spring b) is removed and replaced with a steel bushing. This characteristic is equivalent to that of Fig. 3 if the stiffness of the outer spring (spring 6) is much greater than the stiffness of spring 7.

If, for the cases of Figs. 3 and 4, the inner spring (spring 7) is stiffer, the characteristics become opposite to those shown, i. the friction force will be greater when the shock absorber shrinks.

The friction force remains almost constant during operation since the wear of the friction sleeve is automatically compensated by the pressure of the springs. Due to the significantly larger pre-deformation of the springs relative to the wear of the friction sleeve, the pressure reduction of the springs is insignificant. At any time, the friction force can be adjusted by adding or removing adjusting washers 9.

It is possible to rub the shock absorber.

a variant design of the damper whereby it extends between the shells 3 and the housing 1 of the housing. In this case, the housing must be steel and the shells, pressure cones and springs mounted on the stem. already

The possible characteristics in this considered in Fig. 2, Fig. 3 and the case are the same as Fig. 4. In this embodiment, the shock absorber is more difficult to implement.

Claims (2)

Claims 1. Friction shock absorber consisting of a housing comprising a thin-walled plastic cylinder, to which at one end there is a fixed shaped ear for attaching the shock absorber to a fixed base, and in the cylinder there is an axially arranged steel rod, the outer end of which ends with an ear for joining to the flickering object, characterized in that at the other end of the housing 1 there is a widening in which concentrically three polyamide shells-sections of 120 degrees - 3 are pressed, pressed against the stem 2 by two opposite poses. by means of two conical bushings 4 and 5 and two cylindrical screw springs bi 7 mounted axially in the housing with pre-deformation, whereby the deformation of the springs can be varied by means of washers 9 and cap 8. The friction damper according to claim 1, characterized in that the friction force remains constant during operation, the magnitude of the friction force can be adjusted, and by varying the stiffness and the number of compression springs (one or two ) can also change the characteristics of the shock absorber.