DE29621119U1 - Actuator - Google Patents

Description

Applicant:

Behr GmbH & Co.
Mauserstrasse 3

70469 Stuttgart

Title:

Actuator

0417 197 S/mr

04.12.1996 WP96/10

Description

The invention relates to an actuator with a one-part or multi-part housing, a rolling diaphragm clamped in the housing in a fluid-tight manner, and an actuating element coupled to the rolling diaphragm, which is led out of the housing for actuating purposes.

Such actuators are used in numerous designs and in various areas of technology and are well known as vacuum boxes. For example, an actuator has become known from DE 3 7 41 897 C2, in which a rolling membrane with an actuating element is clamped between two housing halves. Another actuator has become known from DE 36 32 807 C2, in which the actuating element is mounted eccentrically. Finally,

DE 36 07 144 C2 discloses an actuator in which the actuating element leading out of the housing is rotated. All actuators have in common that they are equipped with a rolling membrane which, when the actuator is operated, i.e. when ventilating and venting, rests on the inner surface of the housing and rolls along it. This can result in the rolling membrane being sucked relatively strongly onto the inner surface of the housing when one chamber is vented. If the membrane is now moved when the actuator is ventilated or when the other chamber is vented, it can result in the membrane not rolling evenly but rather that sections of the membrane resting on the inner wall of the housing are lifted off locally, whereas other sections of the membrane remain attached to the inner wall of the housing for a short time. If the pulling forces predominate, then these sections of the rolling membrane are also lifted off, which is usually accompanied by a snapping noise, which is often perceived as annoying. Another disadvantage is that due to the brief adhesion of certain sections of the rolling membrane to the inner wall of the housing, the actuating element is not moved evenly and smoothly, but has a discontinuous movement sequence.

The invention is therefore based on the object of providing an actuator which essentially

works noiselessly and the actuator can be moved evenly and smoothly.

This object is achieved according to the invention in that the housing inner surface in the area in which the rolling membrane rests and rolls is provided with at least one unevenness, in particular with a projection or a recess.

Due to the unevenness on the inner surface of the housing, the actuator according to the invention has the significant advantage that the rolling membrane cannot lie completely against the inner surface ^of the housing in this area, but is at least partially a short distance from it. In this way, the rolling membrane cannot be sucked onto the inner surface of the housing over its entire surface and stick to it in this area. If the actuator is operated, the rolling membrane is evenly and continuously removed from the inner surface of the housing in these areas or can roll along it without any problem. The unevenness can be formed, for example, by a projection, an elevation, a depression, a recess and the like. Both the projections and the recesses prevent the rolling membrane from lying completely against the inner wall of the housing.

In a further development, the unevenness extends essentially in the rolling direction of the membrane. This ensures that in both end positions of the membrane and during the entire rolling process, a full-surface contact is prevented. The membrane therefore rolls over the unevenness. Another advantage of this feature is that such housings are relatively easy to manufacture. They can be deep-drawn or injection-molded, for example. The unevenness extends in the working direction or molding direction of the manufacturing tool.

In order to prevent the rolling diaphragm from being sucked into and sticking to the inner surface of the housing, the unevenness is connected to the ventilation space in the housing. The rolling diaphragm can be undermined by the working fluid along the unevenness, so that when the actuator is ventilated or vented, the corresponding pressure of the working fluid is present on both sides of the rolling diaphragm.

In a preferred embodiment, a full-surface contact of the rolling membrane with the inner surface of the housing is avoided and the rolling membrane can be relatively easily undermined by the working fluid because the transition from the unevenness to the inner surface of the housing has a relatively small radius of curvature or a sharp edge. The rolling membrane has an inherent rigidity that prevents the

The rolling membrane is placed over the unevenness in such a way that the transition from the inner surface of the housing to the unevenness is completely covered by the rolling membrane. In the area of the small radius of curvature or the sharp edge, a ventilation channel is advantageously formed, which allows the working fluid to migrate behind the rolling membrane.

Further advantages, features and details of the invention emerge from the subclaims and the following description, in which particularly preferred embodiments are described in detail with reference to the drawing. The features shown in the drawing and mentioned in the claims and in the description can each be essential to the invention individually or in any combination. In the drawing:

Figure 1 shows a cross section through an embodiment of the actuator according to the invention with a rolling membrane partially in contact with the inner surface of the housing;

Figure 2 shows an enlarged detail II according to Figure 1, a first embodiment of the invention, namely showing an unevenness formed as a detail;

Figure 3 shows an enlarged detail III according to Figure 1, showing a further embodiment of the invention, namely an unevenness designed as a projection.

Figure 1 shows a section through a pot-like, elongated housing 1 of an actuator, designated overall by 2, with a rolling membrane 3 provided within the housing 1. The design of this rolling membrane 3 and its mode of operation is sufficiently known and disclosed, for example, in the documents mentioned at the beginning. The rolling membrane 3 lies against the inner surface of the housing 4, in particular in the areas designated 11 and III. In the more curved areas of the inner surface of the housing 4, which are shown on the left and right sides of Figure 1, the rolling membrane 3 does not lie against the entire surface, which is indicated by the dark, sickle-shaped sections. There, the working fluid flows behind the rolling membrane 3 without any problems.

Figure 2 shows an enlarged reproduction of section II according to Figure 1 and two unevennesses 5 in the form of triangular recesses 6 can be seen on the inner surface of the housing. These recesses 6 merge into the inner surface of the housing 4 at relatively acute angles, so that the rolling membrane 3 cannot follow this deflection, but bridges the recess 6. The recess 6 extends

orthogonal to the plane of the drawing and thus in the rolling direction of the rolling membrane 3 and forms a ventilation channel 7 through which the working fluid can flow between the housing 1 and the rolling membrane 3. This prevents the rolling membrane 3 from sticking to the inner surface 4 of the housing.

Figure 3 shows an enlarged reproduction of section III of Figure 1, which relates to another embodiment. There, the inner surface 4 of the housing is provided with two projections 8, which in this case form the unevenness. Here too, the projection 8 merges into the inner surface 4 of the housing at 9 via a relatively sharp edge. The rolling membrane 4 cannot lie directly against the inner surface of the housing in the area of this sharp-edged transition 9, so that a ventilation channel 7 shown as a black wedge is left out at each transition. As already mentioned above, the working fluid can flow through this ventilation channel 7 between the housing 1 and the rolling membrane 3, so that the latter cannot stick to the inner surface 4 of the housing.

When the actuator 2 is operated, the rolling membrane 3 rolls along the inner surface of the housing 4, which occurs without pressure and continuously, without generating any noise. In addition, this causes the actuating element to move continuously back and forth between the end positions.

Claims (7)

PROTECTION CLAIMS 1. Actuator with a one-part or multi-part housing (1), a rolling membrane (3) clamped in the housing (1) in a fluid-tight manner and an actuating element coupled to the rolling membrane (3) which is led out of the housing (1) for actuating purposes, characterized in that the housing inner surface (4) in the region (II, III) in which the rolling membrane (3) rests and rolls is provided with at least one unevenness (5), in particular with a projection (8) or a recess (6). 2. Actuator according to claim 1, characterized in that the unevenness (5) extends substantially in the rolling direction of the rolling membrane (3). 3. Actuator according to one of the preceding claims, characterized in that the unevenness (5) is connected to the ventilation space in the housing (1). 4. Actuator according to one of the preceding claims, characterized in that the transition (9) from the unevenness (5) to the housing inner surface (4) has a relatively small radius of curvature or a sharp edge. ■# 5. Actuator according to one of the preceding claims, characterized in that the unevenness (5) with
adjacent rolling membrane (3) forms a ventilation channel (7). 6. Actuator according to one of the preceding claims, characterized in that the unevenness (5) is an accumulation of material. 7. Actuator according to one of the preceding claims, characterized in that the unevenness (5) is incorporated into the housing (1) during manufacture.
The inner surface of the housing (4) is formed.