NL8104598A - FLUIDUM TIME ELEMENT, PARTICULARLY PNEUMATIC TIME ELEMENT. - Google Patents

Description

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* v, / VO. 2353.

Subject: Fluid time element, in particular pneumatic time element.

The invention relates to a fluid time element, in particular a pneumatic time element for use in household appliances such as electric toasters, with a cylinder and a piston displaceable therein having a sealing sleeve.

German Patent 2 6 2 ^ 578 shows an pneumatic time element of the type described above, mounted in an electric toaster. The sealing sleeve of the piston always remains in the cylinder, which in its lower region has a cylindrical surface which co-acts with the sealing sleeve and widens in the upper area with an oblique transition so that in the rest position the sealing sleeve this widened space relaxes, rests. With such time elements 15 problems with runtime irregularities arise.

The invention is based on the problem of providing a fluid time element of the type described above with a more uniform transit time.

This problem is solved according to the invention until the transition point between the sliding surface and the widened end portion of the cylinder is designed as a sudden transition with a sharp edge at the end of the sliding surface of that cylinder.

By this simple measure, which in no way means an increase in the manufacturing costs, a considerable uniformity in the runtimes is obtained. The explanation for this action could lie in that the sliding surfaces of the cylinder and / or the sealing sleeve for lubrication are provided with a thin lubricant film, for example silicone grease, for the entire life.

Contaminants can form on this lubricating film, 3 8104598%.

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Such as, for example, granules, plastic material of the cylinder, which are formed during manufacture and remain therein, which lead to leaks between the cylinder and the sealing sleeve or to changes in the frictional ratios.

Such impurities or granules are now rubbed off by the sharp side of the sealing sleeve and retained in the transition points in grease also rubbed off by the sharp side and thus rendered harmless.

The sudden transition is effectively performed as a staircase, which encloses an acute angle with the sliding wall of the cylinder. This angle can be about 90 ° or less, preferably about 60 °.

In the following, exemplary embodiments of the invention will be further elucidated on the basis of the diagrammatically held drawings. In the drawing: figure .1 shows partly in vertical section an electric toaster with a pneumatic time element and figure 2 shows on an enlarged scale another embodiment in section according to figure 1.

The toaster 1 shown in figure 1 has a housing part 2 containing the control unit with a guide b for a tray 6 for the bread and at the opening 8 at the top in which a cylinder 10 of a pneumatic zero-acting switch is grated. The platform 6 has a guide element 12 in the guide U as well as a carrier 1b connected thereto for slicing bread 16.

The carrier extends through a guide slot 18 into the side of the housing part 2 facing the grating chamber 20.

An elastic oblique locking arm 22 formed on the guiding element 12 serves as a locking device for the platform 6 in the lowest grating position, which cooperates with a fixed locking mechanism 2k on the cylinder 10. A tension spring 28 suspended on the one side from the guide element 12 and on the other side on a projection 26 of the housing gives the platform a bias directed towards the top.

In the cylinder 10, a piston 30 made of rubber is slidably mounted and has a piston rod 32, from the bottom of which extends a fastening element 3, for the spring, in which the end of one along the outside of the cylinder 10, the lined tension spring 26 is suspended, the other end of which is suspended in an extension 38 of the cylinder 10 and the piston 10 'pulls into the cylinder.

The piston rod 32 and the guide element 12 have trailing projections Ho and waar2 with which both cooperate with a common lifting element gel which is mounted vertically in the front wall of the housing part 2, which is not shown, and which is provided with a lifting element voorzien provided on the outside of the housing part 2.

Figure 1 shows the parts at the end of the lifting stroke of the element ΗΠ, by the downward movement, on the one hand the tray of the bread pulled downwards against the action of the spring 28 and the bread completely into the toasting chamber 20 and at the same time the momentary operating switch is cocked against the action of the spring 36, while the piston is pulled into the lower position. The locking arm 22 is locked behind the extension 2k of the cylinder at the end of the lifting stroke.

After releasing the lever HU, the piston 30 guides upwards under the influence of the spring 36 in the cylinder 10, the running speed and thus the running time, respectively, the grating time of the position of a throttle screw k6 in an upper air outlet opening of the cylinder 10 depends. The piston group takes the lever HU along via the extension Ho, until it unlocks the locking arm 22 in the position shown in dashed points, whereby the spring 28 lifts the guide element 12 and the platform 6 with the bread 35 back upwards. The rest position of the piston 30 is indicated in broken lines 31.

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In the lower region, the cylinder has a cylindrical sliding surface 6, which is lubricated by a thin film, silicone grease, and with which a sealing sleeve 62 of the piston 30 during operation of the time element 5. works together. Its top connects a widened end portion 66 of the cylinder 10 with a rectangular stage 6b, from which a throttle channel 68, which cooperates with the throttle blade k6, runs out. As soon as the sealing sleeve 62 of the piston 30 has passed the stage 6b, air around the sealing sleeve 62 can escape from the cylinder, whereby the piston jerks into its end position. In the end position, the cuff 62 rests relaxed without touching the walls of the cylinder in the widened end portion 66. When pulling up the extension element. by means of the lever bb, the sleeve 62 is compressed as it passes the step 6b until it extends completely within the narrower cylindrical sliding surface 60.

Figure 2 shows a part of a cylinder 210 with. a cylinder sliding surface 2βθ, to which a widened end portion 266 of the cylinder 210 connects with a transition in the form of a step 26b. A piston 230 shown in the rest position has a sealing sleeve 262, which cooperates sealingly with the sliding surface 2-60 during operation of the time element.

The stage 260 encloses an acute angle of about 75 ° with the sliding surface 26b and merges with the sliding surface 2βθ into a sharp edge 2Ö5. The piston 230 consists of an elastic plastic material or rubber.

8104598

Claims (3)

1. Fluid timing element, in particular pneumatic timing element, to be used in household appliances, such as electric toasters, and a cylinder, which has a sliding surface and a subsequently widened end portion 5 and with a piston having a sealing sleeve, said sleeve interacts sealingly with the sliding surface during operation and is in the rest position, relaxed in the flared end portion of the cylinders, characterized in that the transition point between the sliding surface 10 (60; 260) and the flared end portion (66, 266) of the cylinder (TO; 210) is designed as a sudden transition to a sharp edge (2.65) at the end of the sliding surface. 15 Time element according to claim 1, characterized in that the sudden transition is in the form of a step (6U; 26b), which encloses an acute angle (cc) with the sliding wall (60; 26o) of the cylinder (10; 210). 20 Time element according to claim 2, characterized in that the angle enclosing the stair (6; 26h) with the sliding wall (6θ; 26θ) is about 90 ° or less, preferably about 60 °. 25 8104598