FR2844393A1 - Electric reed bulb switch for a motor vehicle brake reservoir has a support with a mounting structure in the form of a loop or particularly a molded plastic mass that protects the bulb against damage during its in-situ mounting - Google Patents

Abstract

Electric switch comprises a support (33) for two electrically conducting terminals (36, 38) and a reed bulb (32) having an elongated shape that extends along an axis (X). The reed bulb is electrically connected to the two terminals. The support comprises a mounting structure (40) for mechanical protection of the bulb in the form of a loop that surrounds the bulb and extends along its axial direction. Optimally the structure comprises a plastic protection mass molded on the connection terminals surrounding the reed bulb. The invention also relates to a corresponding brake fluid reservoir assembly for a motor vehicle that has an inventive electric switch.

Description

-1 The present invention relates to an electrical switch and a

together

  forming a reservoir for brake fluid comprising this switch.

  An electrical switch of the type already known in the prior art comprises: - a support carrying two electrically conductive terminals and

  - a bulb with tabs, called a "reed" bulb, having a generally elongated shape extending substantially parallel to an axial direction, forming a dipole electrically connected to the two conductive terminals.

  A switch of this type is advantageously used in an assembly

  forming a reservoir for brake fluid for a motor vehicle brake system.

  Generally, an assembly of this type includes a receptacle for liquid

  brake and means for detecting a reference level of brake fluid in the receptacle. These detection means are intended to detect a level of brake fluid corresponding to an insufficient volume of this fluid in the receptacle.

  Usually, the detection means comprise a field source

  magnetic carried by a float, movable substantially vertically in the receptacle, and an electric switch of the aforementioned type, carried by a fixed support integral with the receptacle, capable of changing state as a function of the relative position of the source of magnetic field and of the switch.

  The switch is generally arranged in a housing forming a fixed support, so as to be isolated from the brake fluid contained in the receptacle. When mounted in the housing, the switch may be damaged by impact

  or accidental bending suffered by the reed bulb.

  The object of the invention is to protect the reed bulb from a switch of the aforementioned type from accidental bumps or flexions which this bulb risks undergoing during its

  mounting in its housing-support integral with the receptacle.

  To this end, the subject of the invention is an electrical switch of the aforementioned type, characterized in that the support comprises a mechanical protection armature of the reed bulb forming a loop surrounding the reed bulb and extending substantially

  parallel to a plane containing the axial direction.

  According to other characteristics of this switch: - the armature comprises a protective plastic mass, molded onto the conductive terminals, surrounding the reed bulb; -2 - the support comprises a plastic sleeve, overmolded on two proximal ends of the conductive terminals, extended by the protective plastic mass; the conductive terminals each have a generally planar shape 5 substantially parallel to the axial direction and to the armature in the general form of a loop; the reed bulb extends, at least partially, in an axial cutout of one of the conductive terminals, called a terminal forming mechanical protection, this cutout separating two longitudinal parts of the terminal forming mechanical protection between which the bulb is interposed reed; - The thickness of the frame, measured in a direction substantially perpendicular to a plane parallel to the loop formed by the frame, is substantially equal to, or even greater than, the transverse dimension of the "reed" bulb;

  - the conductive terminals are made of brass.

  The invention also relates to an assembly forming a reservoir for brake fluid for a motor vehicle brake system, of the type comprising: - a receptacle for brake fluid, and - means for detecting a reference level of fluid brake in the receptacle comprising a magnetic field source carried by a

  float, movable substantially vertically in the receptacle, and an electric switch, carried by a fixed support integral with the receptacle, capable of changing state as a function of the relative position of the source of magnetic field and of the switch; 25 characterized in that the electrical switch is as defined above.

  According to another characteristic of this assembly, the fixed support forms a sealed housing for the switch, so as to isolate the latter from the brake fluid.

contained in the receptacle.

  The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:

  - Figure 1 is a vertical sectional view of a reservoir assembly according to the invention;

  FIG. 2 is a perspective view of the switch of the reservoir assembly illustrated in FIG. 1.

  -3 There is shown in Figure 1 an assembly forming a brake fluid reservoir for a motor vehicle brake system. This set according to the invention is

  designated by the general reference 10.

  In what follows, the vertical and horizontal directions correspond to the directions usually defined with respect to a plumb line. The assembly 10 comprises a receptacle 12 for brake fluid delimited by two half-shells respectively lower 121 and upper 12S. The two half-shells 121, 12S, preferably made of plastic, are provided with complementary joining edges delimiting a joint plane J. The upper half-shell 12S of the receptacle comprises means of access to this receptacle provided in particular with a neck 14 carrying screwing means for a

  closure cap of the receptacle, not shown.

  The assembly 10 also includes means 16 for detecting a reference level of brake fluid in the receptacle 12. This reference level of the brake fluid corresponds substantially to a level below which the volume of brake fluid.

  brake in the receptacle is insufficient.

  The detection means 16 comprise a source of magnetic field, constituted for example by a permanent magnet 18, carried by a movable float 20

  substantially vertically in the receptacle 12.

  The float 20 includes lower 201 and upper 20S ends. It will be noted that the magnet 18 is fixed on the float 20 closer to the lower end 201 of this float than to the upper end 20S of this float. Preferably, the magnet 18

  substantially coincides with the lowest point of the float 20.

  The float 20 is guided substantially vertically in the receptacle 12 by cooperation of its external surface with substantially vertical walls 22, 24,

  integral with receptacle 12, extending inside this receptacle 12.

  The vertical stroke of the float 20 is limited by means comprising for example lower 261 and upper 26S stops, integral with the receptacle 12, intended to cooperate respectively with the lower 201 and upper 20S 30 ends of the float. These limit stops 261, 26S of stroke, formed respectively inside the lower half-shells 121 and upper 12S of the receptacle, define

  extreme positions respectively low and high of the float 20.

  The detection means 16 also comprise an electric switch 28, according to the invention, carried by a fixed support 30, integral with the lower half-shell 35 of the receptacle. The fixed support 30, delimited by a wall made of material -4 with the lower half-shell 121, forms a sealed housing for the switch 28, of

  so as to isolate the latter from the brake fluid contained in the receptacle 12.

  It will be noted that the wall delimiting the fixed support 30 carrying the switch 28 forms one of the walls 24 participating in the vertical guidance of the float 20 in the receptacle

12.

  As will be explained in more detail below, the switch 28 is capable of adopting two states as a function of the relative position of the magnet 18 and of

switch 28.

  The switch 28 includes a tab bulb 32, usually called a "reed" bulb. This bulb 32 is carried by a support 33 comprising a socket 34 intended to be fitted into one end of the fixed support 30. Conventionally, the "reed" bulb 32, forming a dipole, is welded on two

  terminals 36, 38 electrically conductive, carried by the socket 34.

  It will be noted that the "reed" bulb 32 has a generally elongated shape 15 extending substantially parallel to an axial direction X. This direction X is

  substantially perpendicular to the plane of Figure 1.

  The conductive terminals 36, 38, preferably made of brass, have a generally planar shape substantially parallel to the axial direction X. In the following, an element of the switch 28 will be described as proximal, when it is close to the axial axis. the socket 34, and distal, when it is distant

axially of this socket 34.

  The conductive terminals each include a proximal end 36P, 38P and a distal end 36D, 38D. It will be noted that the proximal ends 36P, 38P of the conductive terminals are offset between them in a direction transverse to the axis X. On the other hand, the distal ends 36D, 38D of the conductive terminals are offset axially between them, parallel to the axis X. The "reed" bulb 32 is

  soldered to the distal ends 36D, 38D of the conductive terminals.

  The socket 34 is made of plastic. It is molded on both ends

  proximal 36P, 38P of the conductive terminals.

  The support 33 also includes a frame 40 for mechanical protection of the "reed" bulb 32. This frame 40 forms a loop surrounding the "reed" bulb 32 and extending substantially parallel to a plane containing the axial direction X. L frame 40 comprises a protective mass 42 of plastic, molded 35 on the conductive terminals 36, 38. This plastic mass 42 delimits the loop

surrounding the "reed" bulb 32.

  Preferably, the plastic protective mass 42 extends the plastic sleeve 34, the latter and the mass 42 being formed in a single operation of

  overmolding on the conductive terminals 36, 38.

  It will be noted that the conductive terminals 36, 38, of generally planar shape, are substantially parallel to the loop delimited by the frame 40. The "reed" bulb 32 extends, at least partially, in an axial cutout 44 formed in the distal end 38D of one of the terminals called terminal forming mechanical protection 38. This cutout 44 separates two longitudinal parts 381, 382 of terminal 38 forming a mechanical protection between which the bulb 10 "reed" 32 is interposed. These two longitudinal parts 381, 382 of terminal 38 form means

  for attaching the protective plastic mass 42.

  It will be noted that, preferably, the thickness of the reinforcement 40, measured according to

  a direction substantially perpendicular to a plane parallel to the loop formed by the frame 42, is substantially equal to, or even greater than, the transverse dimension of the "reed" bulb 32 so as to optimize the protection of this "reed" bulb 32.

  The frame 40 allows the switch 28 to be rigidified axially so as to prevent accidental bending of the "reed" bulb 32 which may damage it. Furthermore, the frame 40 effectively protects the "reed" bulb 32

  against shocks substantially transverse to the axial direction of the switch 28.

  In accordance with a conventional operation of the “reed” bulb 32,

  the switch 28 adopts a first state when this bulb 32 is under the influence of the magnetic field of the magnet 18 and a second state when this bulb 32 is released from the influence of the magnetic field of the magnet 18. In the In the example described, the first and second states of switch 28 are respectively closed and open states 25 of this switch 28.

  Note that the magnet 18 is carried by a part of the float 20 offset

  horizontally with respect to the switch 28.

  Thus, the switch 28 adopts its first state (closed switch) when the magnet 18 is substantially aligned horizontally with this switch 28 (minimum distance 30 between the magnet 18 and the switch 28) and its second state (open switch) when the magnet 18 is vertically offset from the switch 28, like this

is shown in Figure 1.

  The upper stop 26S is positioned inside the receptacle 12 so that the magnet 18 and the switch 28 are substantially aligned horizontally 35 when the upper end 20S of the float cooperates with this stop 26S to limit the stroke of this float in height. Thus, when the volume of brake fluid in the receptacle -6 is sufficient to keep the upper end 20S of the float in contact

  with the upper stop 26S, the switch 28 is closed.

  When the brake fluid level drops in the receptacle 12, the float is driven downwards. The magnet 18 therefore moves away from the switch 28, by vertical offset 5, by passing this switch 28 into its second state (switch open) as soon as the liquid level reaches a predetermined reference level below which the volume insufficient liquid in receptacle 12. The change of state of the switch 28 makes it possible to trigger an alarm warning the user of the vehicle that he

  should restock the assembly 10 with brake fluid.

  Note that the reference level below which the volume of liquid in the receptacle is insufficient is imposed by the height position of the switch 28. -7

Claims (9)

  1. An electrical switch of the type comprising: - a support (33) carrying two electrically conductive terminals (36, 38) and - a bulb (32) tabs, called a "reed" bulb, having a generally elongated shape extending substantially parallel to an axial direction (X), forming a dipole electrically connected to the two conductive terminals (36, 38), characterized in that the support (33) comprises a frame (40) for mechanical protection of the reed bulb (32) forming a loop surrounding the reed bulb (32) and extending substantially parallel to a plane containing the direction axial (X).   2. Electric switch according to claim 1, characterized in that the armature (40) comprises a protective mass (42) of plastic, molded onto the   conductive terminals (36, 38), surrounding the reed bulb (32).   3. Electric switch according to claim 2, characterized in that the   support (33) comprises a plastic sleeve (34), overmolded on two proximal ends (36P, 38P) of the conductive terminals (36, 38), extended by the protective plastic mass (42).   4. Electric switch according to any one of claims   previous, characterized in that the conductive terminals (36, 38) each have a generally planar shape substantially parallel to the axial direction (X) and to the armature (40) generally in the form of a loop.   5. Electric switch according to claim 4, characterized in that the reed bulb (32) extends, at least partially, in an axial cutout (44) of one of the conductive terminals (36, 38), called terminal ( 38) forming mechanical protection, this cutout (44) separating two longitudinal parts (381, 382) of the terminal (38) forming   mechanical protection between which the reed bulb (32) is inserted.   6. Electric switch according to any one of claims   above, characterized in that the thickness of the armature (40), measured in a direction substantially perpendicular to a plane parallel to the loop formed by the armature (42), is substantially equal to, or even greater than, the transverse dimension of the 'x reed' bulb (32).   7. Electric switch according to any one of claims   previous, characterized in that the conductive terminals (36, 38) are made of brass.   -8 8. Assembly forming a reservoir for brake fluid for a motor vehicle brake system, of the type comprising: - a receptacle (12) for brake fluid, and - means (16) for detecting a reference level brake fluid 5 in the receptacle (12) comprising a source (18) of magnetic field carried by a float (20), movable substantially vertically in the receptacle (12), and an electric switch (28), carried by a support fixed (30) integral with the receptacle, capable of changing state as a function of the relative position of the source (18) of magnetic field and of the switch 10 (28), characterized in that the electric switch (28) is according to one   any of the preceding claims.   9. An assembly according to claim 7, characterized in that the fixed support   (30) forms a sealed housing for the switch (28), so as to isolate the latter from the brake fluid contained in the receptacle (12).