GB2178238A

GB2178238A - Fluid reservoir filling level indicating device

Info

Publication number: GB2178238A
Application number: GB08615535A
Authority: GB
Inventors: Peter Tandler; Peter Boehm
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co OHG
Priority date: 1985-07-06
Filing date: 1986-06-25
Publication date: 1987-02-04
Also published as: DE3524281C2; SE8602645D0; GB2178238B; FR2584491B1; FR2584491A1; SE461299B; DE3524281A1; SE8602645L; GB8615535D0

Abstract

A guide tube (2) alongside of which a float (3) is displaceably arranged extends into the fluid reservoir (1). The float (3) comprises a magnet (4) by means of which at least one reed switch (8) arranged inside the guide tube (2) is actuatable when the float reaches a predetermined position. The reed switch (8), which is mounted on a support (7) which is initially displaceable inside the guide tube (2), is connected through the intermediary of electric wires (29) protruding from the interior of the guide tube (2) to plug-and-socket connector contacts (27) arranged in a cap (23). At its end directed towards the opening of the guide tube (2), the support (7) is connected to a lug (11) arranged parallel to the axial direction of the guide tube (2) and radially outwardly projecting over said support. The lug (11) is guided in a slit (13). The lug (11) is attachable between two projections adjoining the slit (13) after the reed switch has been adjusted to its required position. The interior of the guide tube (2) and a wider hollow space (17) adjacent thereto are closable by means of the cap (23) associated with the plug-and-socket connector contacts (27). <IMAGE>

Description

SPECIFICATION Fluid reservoir filling level indicating device This invention relates to a device for indicating the filling level in a fluid reservoir, in particular in a vehicular hydraulic brake system, and in particular to a fluid reservoir including such a device and comprising a guide tube extending into the fluid reservoir, alongside of which guide tube a float is displaceably arranged, said float comprising a magnet by means of which at least one reed switch arranged inside the guide tube is actuatable when the float reaches a predetermined position, said reed switch being connected through the intermediary of electrical wires protruding from the interior of the guide tube to plug-and-socket connector contacts arranged in a cap.

An arrangement of this kind is already known from West German printed and published patent application 30 21 424. In the known arrangement, the reed switch sealed in a glass tube is secured in the guide tube in an axial position by means of a filler. The fluid reservoir as well as the guide tube which is closable by means of the cap are provided with bayonet-type connecting elements. The guide tube comprises at its end adjacent to the wall of the fluid reservoir a cylindrically enlarged portion which serves to accommodate the electrical wires leading to the connecting terminals in the cap.

A test equipment for a float-controlled filling level measuring device known from West German printed and published patent application 22 25 289 comprises a first tube which is hollow on the inside and around which a second tube is concentrically arranged. Between both tubes, a displaceable float is provided which is equipped with a magnet through the intermediary of which a read switch arranged inside the first tube is actuatable when the float assumes a specific position. The second tube is at one end connected to a screw cap which is screwed onto the fluid reservoir. The first tube is displaceably arranged in the second tube. Electrical wires projecting from the first tube are secured in their position at the end of the first tube by means of a sealing element.

A device responding to the fluid level for triggering an indication is also known, said device being provided with a tube which is firmly closed at one end and which is at its other end attched to a flange which covers an opening of the reservoir. Inside the tube, a reed switch is arranged which is actuatable by means of a magnet held by a float which is arranged on the outside of the tube (West German printed and published patent application 18 63 375).

In a device for measuring the fluid level in a reservoir covered by a cap known from the United States Patent Application 4 107 494, a fluid level sensor is inserted in an opening of the cap and attached to the opening. The fluid level sensor comprises a guide tube for a float, which guide tube protrudes into the reservoir and is closed at one end, said float carrying a magnet by means of which a switch arranged inside the guide tube is actuated when the float assumes a specific position. The switch is secured in the guide tube in its position by a synthetic filler. Between the cap and the portion of the guide tube adjacent the cap a diaphragm is mounted which is situated in the space between the fluid level and the inside of the cap.

Reed switches have, as compared with mechanical switches, considerably larger switching tolerances. In addition, differing specific weights of the floats and varying field strengths of the magnets have the effect that the reed switch is not always actuated at identical fluid levels in different reservoirs.

Therefore, the reed switches must be so adjusted with respect to the magnet by means of axial displacement that the switch is always actuated at an identical filling level.

For this reason, we have previously proposed a method by which the adjustment between the reed switches and the magnets is so effected during the production of a fluid reservoir as to permit an actuation at identical fluid levels in all reservoirs. By means of this method, the float is held in a predetermined position during the insertion of a support carrying one or a plurality of reed switches into the interior of the guide tube. The supports equipped with the reed switches and the electrical wires connected thereto are shifted relative to the float until a reed switch is actuated. The shifting movement is then interrupted. Subsequently, the support with the reed switches and the connecting wires are secured in their position.

Due to the adjustment of the reed switch support relative to the float it is no longer possible to accommodate the reed switch and the connecting terminals in a common housing. The reed switches and the connecting terminals must be interconnected by means of electrical wires and/or a cable. For safety reasons, the plug must be attached to the reservoir housing and the electrical wires and/or the cable must be located in a chamber inside the reservoir. Furthermore, the reed switch must be secured against axial displacement in the guide element. In addition, the guide tube must be covered. By means of these measures, an unintentional damage to or shifting of the reed switch and/or switches is prevented.

The present invention has as an object to create a reservoir including a filling level indicating device of the type initially referred to, wherein an exact adjustment of the reed switches in the axial direction of the guide tube, an accommodation of the electrical wires an d/or cables between the reed switches and the connecting elements and a safe covering of the reed switches and the electrical wires is possible with the aid of simple means.

According to one aspect of the present invention there is provided a fluid reservoir including a device for indicating the fillng level thereof, comprising a guide tube extending into the fluid resevoir, alongside of which guide tube a float is displaceably arranged, said float comprising a magnet by means of which at least one reed switch arranged inside the guide tube is actuatable when the float reaches a predetermined position, said reed switch being connected through the intermediary of electrical wires protruding from the interior of the guide tube to plug-and-socket connector contacts arranged in a cap, characterised in that the reed switch is mounted on a support arranged inside the guide tube, said support being at its end directed towards an opening of the guide tube connected to a lug running parallel to the axial direction of the guide tube and radiallly outwardly projecting from the support, said lug being disposed in a slit of the guide tube and being attached between two projections of the guide tube adjacent to the slit, the lug being secured to the two projections whereby the reed switch is disposed so that it will be actuated when the float reaches the predetermined position, and in that the interior of the guide tube and a radially wider hollow space adjacent thereto is closable by means of the cap which forms a unit with the plug-and-socket connector contacts.

According to another aspect of the present invention there is provided a device for use in combination with a fluid reservoir for indicating the filling level thereof, the device including a guide tube which in use of the device extends into the fluid reservoir, a float displaceably arranged alongside the guide tube, said float comprising a magnet by means of which at least one reed switch arranged inside the guide tube is actuable when the float reaches a predetermined position in use of the device, said reed switch being connected through the intermediary of electrical wires protruding from the interior of the guide tube to plug-andsocket connector contacts arranged in a cap, characterised in that the reed switch is mounted on a support arranged inside the guide tube, said support being at its end directed towards an opening of the guide tube connected to a lug running parallel to the axial direction of the guide tube and radially outwardly projecting from the support, said lug being disposed in a slit of the guide tube and being attached between two projections of the guide tube adjacent to the slit, the lug being secured to the two positions whereby the reed switch is so disposed that it will be actuated when the float reaches the predetermined position, and in that the interior of the guide tube and a radially wider hollow space adjacent thereto is closable by means of the cap which forms a unit with the plug-and-socket connector contacts.

The interior of the guide tube serves at the same time to accommodate the electric wires and/or cables. The cap provided with the connecting elements covers both the interior of the guide tube and the space for accommodating the wires adjacent thereto as well as the adjusting means for the reed switch support. The reed switch is thus protected against a subsequent shifting. The connecting points of the electric wires on the reed switch and on the external connecting elements are protected against contamination and corrosion.

The space adjacent to the open end of the guide tube is shaped in the form of a hollow space which is shallow relative to the axial direction of the guide tube. The electrical wires and/or the cable can be easily and quickly inserted into the said space for accommodating wires when the cap which is, for example, attachable by means of snap elements is placed onto the fluid reservoir.

In a preferential embodiment of the present invention, the lug is connected at one end with the support of the reed switch through the intermediary of an intermediate member running obliquely to the longitudinal axis of the guide tube. In this manner, the wires and/or cables can be easily inserted into the space between the reed switch support and the cap.

Preferably, the support for the reed switch and/or switches is shaped in the form of two crossed plates. This support can be manufactured in a simple manner. It is easily displaceable inside the guide tube. In addition, it is possible to attach a plurality of reed switches between the plates, if necessary.

In an improvement of the present invention it is provided that the cap has a recess in longitudinal direction of the lug arranged in the slit. In such an embodiment, the space above the guide tube can have a very shallow shape without impairing the relatively large axial adjustment travel of the support of the reed switches.

It is expedient to mount the cap on the reservoir so as to be fluid-tight and dust-tight.

This is achieved in a simple manner by welding. The reed switch and the connecting points between the wires and the reed switch are thus protected particularly well.

An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal cross-section through part of a reservoir and a device for indicating the filling level in the fluid reservoir; Figure 2 shows a top view of the arrangement illustrated in Figure 1 without a cap; Figure 3 shows a sectional view taken along the line I-I of Figure 2; Figure 4 shows a perspective top view of the device inserted in the reservoir but without the cap, and Figure 5 shows a perspective view of the device comprising a cap, a reed switch with a support and connecting wires between connecting elements in the cap and a reed switch.

A fluid reservoir 1 for a hydraulic fluid, preferably a brake fluid, is, for instance, attached to a master cylinder of a vehicular brake system, which master cylinder is not illustrated in the drawing. The fluid reservoir 1 is connected with a guide tube 2 extending into its interior, said guide tube being closed at its end directed towards the interior of the reservoir. Alongside the guide tube 2, which preferably has a circular cross-section, a float 3 which is, for instance, shaped in the form of a ring is displaceably arranged. The float 3 carries an annular magnet 4. A tube socket 6 upwardly extending from the bottom 5 of the fluid reservoir 1 and co-axially surrounding the guide tube 2 in part is provided as a stop for the float 3. This stop determines the lowest position of the float in the fluid reservoir 1 and prevents the float 3 from leaving the guide tube 2.

Inside the guide tube 2, a support 7, attached to which is a reed switch 8, is arranged and displaceable initially in the longitudinal axial direction of the guide tube. The support 7 is provided with two plates 9, 10 arranged crosswlise. At the plate 10, the reed swtich 8 is fastened with its oblong glass body in the space formed between the plates 9 and 10. The support 7 is so designed as to be slidable inside the guide tube 2.

At the support 7, a lug 11 extending parallel to the longitudinal axis of the guide tube 2 is fastened. The lug 11 which is connected with the upper end of the plate 9 of the support 7 through the intermediary of an intefme- diate member 12 inclined to the longitudinal axis of the guide tube 2, is arranged radially outwardly of the rim of the support 7. The lug 11 provided with even (flat) side faces protrudes into an inner slit 13 of a radial projection 14 of the guide tube 2. The projection 14 forms together with a stepped portion 15 of the guide tube the upper stop for the float 3.

At its upper end, the guide tube 2 changes into a bottom 16 of a shallow hollow space 17, the side wall 18 of which is connected with the walls 19, 20 and 21 of the fluid reservoir 1. The side wall 18 projects a slight length above the walls 19, 20 of the fluid reservoir 1 and constitutes with its upper rim a stop for a cap 23 comprising a flat base plate 24 upwardly extending from which is a plug-and-socket connector housing 25. The plug-and-socket connector housing 25 is provided with a recess 26 extending in which is a contact pin 27 or a knife contact of a plugand-socket connector which is with one end inserted into the plug-and-socket connector housing 25 so as to be gas-tight and/or fluidtight. The end 28 of each of, for example, two contact pins 27, which end is opposite to the recess 26, is connected with the end of a respective electrical wire 29.The other ends of the electrical wires 29 are connected to the reed switch 8. The wires 29 can also be arranged in a cable.

Two projections 30 prolonging the walls a little on opposite sides of the slit 13 protrude into the hollow space 17, said projections being, for example, not higher than the side wall 18. The lug 11 extends into the chamber 17 between the projections 30. In the plug-andsocket connector housing 25, a recess 31 is provided in the part situated above the projections 30, protruding into which recess 31 are the end of the lug 11 and, if necessary, the projections 30 when the cap 23 closes the hollow space 17. The fluid reservoir 1 comprises an upper part 32 and a lower part 33 which parts are welded together at their rims 34.

The assembling method for the device with the reservoir will be explained in more detail in the following, from which the major advantages of the present invention will become apparent.

First of all, the plug-and-socket connector housing 25 with the inserted plug-and-socket connectors is connected with the electrical wires 29 and the support 7 so as to form a unit before the assembly with the fluid reservoir 1 is carried out. The electrical wires 29 are, for example, soldered on the connecting ends of the contact pins 27 and the reed switch 8. Subsequently, the support 7 is inserted into the hollow space 35 of the guide tube 2 such that the lug 11 is, in part, located in the slit 13 and, in part, between the projections 30. In the slit 13 and between the projections 30, the lug 11 can be displaced in the directions marked with the arrow 36. With the cap 23 removed and with the float 3 assuming a reference position, the support 7 is so adjusted in the hollow space 35 that the reed switch 8 responds when the desired filling level is reached.The lug 11 is then connected in this position with the projections 30. This can be effected, for example, by bonding, welding, screwing or pressing the projections 30 onto the lug 11 in the directions marked with the arrows 37.

After having secured the support 7 in the correct axial position in the guide tube 2, the cap is placed onto the rim 22. When the cap 23 approaches the hollow space 17, the electrical wires 29 occupy the hollow spaces 17 and 35. The hollow space 17 and the hollow space 35 above the support 7 thus constitute chambers for accommodating the connecting wires 29. The chamber provided for accommodating the connecting wires 29 is sufficient for that purpose. The cap 23 can therefore be placed onto the rim 22 without damaging the wires 29. After having placed the cap 23 onto the rim 22, the cap can be secured by welding. A dust-tight and fluid-tight connection is thus provided between the cap and the fluid reservoir 1. The connecting points between the wires 29 and the reed switch 8 as well as the contact pins 27 are protected after the attachment of the cap 23 onto the fluid reservoir 1. The reed switch 8 is safeguarded against subsequent unintentional shifting.

By means of the device explained above it is possible to accommodate the reed switch 8 together with the wires 29 and the connecting points of the wires 29 in a common, tightly lockable hollow space. Therefore, an unintentional shifting or displacing of the reed switch 8, the wires 29 and their connecting points is no longer possible.

Claims

1. A fluid reservoir including a device for indicating the fillng level thereof, comprising a guide tube extending into the fluid resevoir, alongside of which guide tube a float is displaceably arranged, said float comprising a magnet by means of which at least one reed switch arranged inside the guide tube is actuatable when the float reaches a predetermined position, said reed switch being connected through the intermediary of electrical wires protruding from the interior of the guide tube to plug-and-socket connector contacts arranged in a cap, characterised in that the reed switch (8) is mounted on a support (7) arranged inside the guide tube (2), said support being at its end directed towards an opening of the guide tube (2) connected to a lug (11) running parallel to the axial direction of the guide tube and radiallly outwardly projecting from the support, said lug being disposed in a slit (13) of the guide tube and being attached between two projections (30) of the guide tube adjacent to the slit (13), the lug being secured to the two projections whereby the reed switch is disposed so that it will be actuated when the float reaches the predetermined position, andin that the interior of the guide tube (2) and a radially wider hollow space (17) adjacent thereto is closable by means of the cap (23) which forms a unit with the plug-andsocket connector contacts.

2. A fluid reservoir as claimed in claim 1, characterised in that the lug (11) is connected with the support (7) of the reed switch (8) through the intermediary of an intermediate member (12) running obliquely to the longitudinal axis of the guide tube (2).

3. A fluid reservoir as claimed in claim 1 or claim 2, characterised in that the support (7) for the reed switch (8) is shaped in the form of two crossed plates (9, 10).

4. A fluid reservoir as claimed in any one of the preceding claims, characterised in that the cap (23) has a recess (31) in the longitudinal direction of the lug (11) which is arranged in the slit (13).

5. A fluid reservoir as claimed in any one of the preceding claims, characterised in that the hollow space (17) adjacent to the opening of the guide tube (2) is shaped in the form of a rectangular parallelepiped and is shallow in the axial direction of the guide tube.

6. A fluid reservoir as claimed in any one of the preceding claims, characterised in that the projections (30) protrude into the hollow space (17).

7. A fluid reservoir as claimed in any one of the preceding claims, characterised in that the cap (23) is provided with a base plate (24) which is attached to the rim (22) of a side wall (18) of the hollow space (17) so as to be dust-tight and fluid-tight.

8. A fluid reservoir as claimed in any one of the preceding claims, characterised in that the guide tube (2), a side wall (18) of the hollow space (17) and the projections (30) are of integral design with an upper part (32) of the fluid reservoir (1), and further including a lower fluid reservoir part (33) which is gastightly and fluid-tightly attachable to the upper part.

9. A fluid reservoir as claimed in any one of the preceding claims, characterised in that contact pins (27) of the plug-and-socket connector are gas-tightly and/or fluid-tightly inserted into a plug-and-socket connector housing (25) projecting from a base plate (24) of the cap (23).

10. A fluid reservoir including a device for indicating the filling level thereof substantially as herein described with reference to and as illustrated in the accompanying drawings.

11. A device for use in combination with a fluid reservoir for indicating the filling level thereof, the device including a guide tube which in use of the device extends into the fluid reservoir, a float displaceably arranged alongside the guide tube, said float comprising a magnet by means of which at least one reed switch arranged inside the guide tube is actuable when the float reaches a predetermined position in use of the device, said reed switch being connected through the intermediary of electrical wires protruding from the interior of the guide tube to plug-and-socket connector contacts arranged in a cap, characterised in that the reed switch (8) is mounted on a support (7) arranged inside the guide tube (2), said support being at its end directed towards an opening of the guide tube (2) connected to a lug (11) running parallel to the axial direction of the guide tube and radially outwardly projecting from the support, said lug being disposed in a slit (13) of the guide tube and being attached between two projections (30) of the guide tube adjacent to the slit (13), the lug being secured to the two positions whereby the reed switch is so disposed that it will be actuated when the float reaches the predetermined position, and in that the interior of the guide tube (2) and a radially wider hollow space (17) adjacent thereto is closable by means of the cap (23) which forms a unit with the plug-and-socket connector contacts.

12. A device as claimed in claim 11, characterised in that the lug (11) is connected with the support (7) of the reed switch (8) through the intermediary of an intermediate member (12) running obliquely to the longitudinal axis of the guide tube (2).

13. A device as claimed in claim 11 or claim 12, characterised in that the support (7) for the reed switch (8) is shaped in the form of two crossed plates (9, 10).

14. A device as claimed in any one of claims 11 to 13, characterised in that the cap (23) has a recess (31) in the longitudinal direction of the lug (11) which is arranged in the slit (13).

15. A device as claimed in any one of claims 11 to 14, characterised in that the hollow space (17) adjacent to the opening of the guide tube (2) is shaped in the form of a rectangular parallelepiped and is shallow in the axial direction of the guide tube.

16. A device as claimed in any one of claims 11 to 15, characterised in that the projections (30) protrude into the hollow space (17).

17. A device as claimed in any one of claims 11 to 16, characterised in that the cap (23) is provided with a base plate (24) which is attached to the rim (22) of a side wall (18) of the hollow space (17) so as to be dusttight and fluid-tight.

18. A device as claimed in any one of claims 11 to 17, characterised in that contact pins (27) of the plug-and-socket connector are gas-tightly and/or fluid-tightly inserted into a plug-and-socket connector housing (25) projecting from a base plate (24) of the cap (23).

19. A device for use in combination with a fluid reservoir for indicating the filling level thereof, substantially as herein described with reference to and as illustrated in the accompanying drawings.