WO1998038663A1

WO1998038663A1 - Plastics body wetted with a mineral-oil-containing substance as switching arrangement

Info

Publication number: WO1998038663A1
Application number: PCT/EP1998/000939
Authority: WO
Inventors: Felix Fenner
Original assignee: Itt Manufacturing Enterprises, Inc.
Priority date: 1997-02-27
Filing date: 1998-02-19
Publication date: 1998-09-03
Also published as: DE19707840A1

Abstract

The invention concerns a warning arrangement for triggering an alarm in the event of the content of a liquid container being contaminated by another, hazardous liquid. To that end, according to the invention, a plastics body which swells in the contaminating liquid displaces the float (7) in a liquid container in the same direction which determines the direction of movement of the float when the liquid level drops. As a result, the float can trigger an alarm when the liquid is contaminated, as it does when the liquid level drops significantly.

Description

Plastic body wetted with a mineral oil-like substance as a switching device

The invention relates to a switching device in which an electrical circuit or a liquid path is to be closed (or possibly also opened in the opposite direction) when a mineral oil-like substance is perceived in the monitored space.

Devices of this type are important in order to determine in the room to be monitored whether a mineral oil-like substance is present. The presence of this substance may or may not be desirable. It is essential that the appropriate measures, for example an electrical warning signal or the closing of a circuit, be carried out after the detection of this substance.

The invention is therefore based on a switching device according to the preamble of claim 1. The object of the invention is to disclose a very simple and effective switching direction of this type which, moreover, can be produced very inexpensively and optionally retrofitted.

The invention is achieved by the combination of features resulting from the characterizing part of claim 1. In principle, the invention therefore consists in arranging a body in the room to be monitored, which reacts with the mineral oil-like substance due to its physical properties and triggers the desired processes due to its spatial, mechanical change, which, for example, in an electrical warning signal or a mechanical interlock of a path connected to the monitored space. In particular, special plastics that swell under the action of mineral oil-like substances and in particular mineral oil themselves have proven themselves here. This change in volume can be used within the scope of the invention to close a warning contact or to close a valve or, if necessary, to interrupt a warning circuit in the opposite direction or to open a fluid path via a valve. The use of a plastic body is very inexpensive. The plastic body can also be easily adapted to the desired spatial conditions, since molded plastic parts can be easily deformed. However, it must be ensured that the swelling process and thus the change in volume of the plastic body require a longer reaction time, so that the present device is less suitable for devices that trigger quickly when mineral oil-like substances occur. On the other hand, the plastic body has the property of swelling essentially only with mineral oil-like substances. In this way, it is possible to arrange the plastic body in a liquid in which it does not swell and then to monitor this liquid with the help of the plastic body to determine whether non-mineral oil-like substances occur in it, for example as an impurity. The switching device according to the invention is therefore outstandingly suitable for monitoring a liquid, for example the brake fluid of a hydraulic circuit of a brake system, for contamination with substances containing mineral oil. Of course, the switching device according to the invention also reacts in particular if a container has been accidentally filled with a mineral oil-like substance, in particular mineral oil itself, instead of with brake fluid. By triggering an electrical contact and / or blocking the path to the brake circuit for the mineral oil that has entered the brake fluid container, it is achieved that the devices arranged in the brake fluid circuit are not attacked or destroyed, which can happen in particular if they are also made of plastic are built up. The comparatively early warning not only prevents the mineral oil-containing substance from entering the brake fluid reservoir into the brake fluid circuit. The electrical contact also ensures that a warning signal prompts the driver to have his brake circuit checked, so that under certain circumstances the contaminated brake fluid can be replaced in good time.

In further training, the use of the combination of features according to claim 2 is recommended.

If the fluid path of the brake fluid between the container and the legal brake fluid is to be interrupted, then in a further development of the invention the combination of features according to claim 3 is recommended the brake fluid floats. If the brake fluid level drops, for example as a result of the consumption of the brake fluid or as a result of a leak, the float also drops until it finally triggers an electrical contact. The development according to claim 3 now proposes that the plastic body acts on the float. If the plastic body expands, it moves the float regardless of the actual fluid level in a direction that it would take if the fluid level dropped. In this way, the float can be made to trigger a warning signal or use the float to close the path between the reservoir and the brake circuit, even though the fluid level in the reservoir is comparatively large. Of course, this will only happen if the plastic body expands, ie if the container contains a mineral oil-like liquid in a strong or less strong concentration. The swelling rate of the plastic body depends on the mineral oil concentration, so that the switching device reacts comparatively quickly at a high concentration. The switching device is very well suited to be retrofitted into existing brake fluid containers. Of course, it can also be advantageously inserted into new (brake fluid) containers. For this purpose, the use of the combination of features according to claim 4 is recommended in a further development. The plastic body expands in a direction that corresponds to the direction of movement of the float when the liquid level drops.

A separate warning device can be provided as an electrical warning device for the plastic body, which, for example, responds even to small changes in volume of the plastic body. But it can also be inserted into the known electrical warning device of the liquid container, which is usually triggered by the floating body. The combination of features according to claim 5 is particularly recommended for this purpose. A particularly simple configuration for the plastic body results from the combination of features according to claim 6. This ensures that the force exerted by the plastic body acts concentrically on the float.

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is washed around and can therefore expand quickly. It is also possible that the plastic body itself acts as a valve body and closes an opening 18 at the bottom of the container via the float 7 or directly. This can be a throttle bore 18, for example, which is inserted in a disc 20 located at the bottom of the container.

Claims

claims

1. Switching device which triggers a switching operation when a mineral oil-containing substance comes into contact, characterized in that the switching device is provided with a plastic body (13) which expands with at least local wetting with the mineral oil-containing substance and thereby actuates an electrical contact and / or opens or closes a fluid path.

2. Switching device according to claim 1, characterized in that the electrical contact (10,11) is connected to an electrical warning device which triggers an alarm when contact is made.

3. Switching device according to claim 1 or 2, characterized in that the plastic body (13) with a float (7) can be coupled, which acts on the electrical contact (10, 11) and / or opens or closes the liquid path (18) .

4. Switching device according to claim 3, characterized in that the floating body (7) on a shoulder (5) on a lid (3) of a liquid container (1) or on the wall of the container (1) is guided and that the plastic body (13) with one end (17) is also supported on the wall or the cover (3) and optionally acts on the float (7) with its other end.

5. Switching device according to claim 4, characterized in that the float (7) with a in the cover extension (5) guided guide pin (6) is provided, which at its end facing away from the float (7) with a con tact piece (10) is provided, which optionally acts on two through the cover (3) guided, with respect to the cover (3) fixed contact lines (11).

6. Switching device according to claim 5, characterized in that the plastic body (13) is essentially a hollow cylinder which concentrically surrounds the guide pin (6), the hollow cylinder preferably being clamped to the outer surface of the cover extension (5).

7. Switching device according to one of the preceding claims, characterized in that the container (1) is a brake fluid reservoir of a motor vehicle, the fluid is brake fluid and the mineral oil-like fluid is mineral oil.

8. Switching device according to one of the preceding claims, characterized in that the plastic body (13) is made of the material EPDM, since clearly swellable materials

EPDM

Silicone rubber CR materials have the same effect.

9. Switching device according to one of the preceding claims, characterized in that a valve (18) is closed in a fluid path by the mechanical expansion of the plastic body (13).