State of charge indicator for a battery

The invention relates to a state of charge indicator for a liquid with a Electrolyte battery equipped with a transparent viewing rod a first end of an observation area and a second end, a adjacent to a cylindrical outer surface, by a conical reflection surface has formed tip, and a second end Viewing rod attached, through which the electrolyte ball cage, in the at least one obliquely arranged to the longitudinal direction of the light rod Ball guide channel for at least one ball with a defined specific Weight is formed, which extends over the height of the tip of the viewing rod extends and frontal and lower limits and a at a Interruption for the second end of the viewing rod provided upper boundary wall having.

Such state of charge indicator is based on the fact that the specific Weight of the electrolyte in function of the state of charge changes. The specific gravity of the run in the ball guide channel ball is therefore adapted to the specific gravity of the electrolyte, so that the Ball more easily at a proper charge of the battery as the electrolyte is and therefore floats in the slanting channel. However, if the battery discharged, the specific gravity of the electrolyte falls below that of the ball, so that the ball in the ball guide channel drops down.

According to DE 25 11 426 C2, an oblique ball guide channel is provided, which ends at the tip of the viewing rod. Floats on the ball, because the battery is sufficiently charged, the ball is at the end of the viewing rod visible through the viewing surface at the first end. By color Education of the sphere can be as a color display (z. B. green) for the proper state of charge implement. The reflective surface on second end of the viewing rod, a sufficient degree of filling of the battery is further visible with the electrolyte. Indeed, if the electrolyte level fallen so far that the tip of the viewing rod is no longer immersed in the electrolyte, form the conical surfaces of the tip of the viewing rod an interface with air, whereby the conical surfaces of the tip of the viewing rod a total reflection occurs, so that the tip as a reflective surface, ie bright, appears. In contrast, if the electrolyte level is sufficiently high, the material selected the viewing rod so that the refractive indices of the viewing rod and the electrolyte are approximately equal, so that no total reflection more arises. With the tip of the viewing rod is thus an optical link produced with the (dark) inside of the battery, so that at the observation area (Without ball) a dark area appears. Of course is a sphere only visible if the electrolyte level is sufficiently high, on the one hand the ball without electrolyte can not float on the other hand the reflection surfaces at the tip of the viewing rod total reflection cause, ie an observation not a continuation of the light rod enable. Visible are thus three different states at the observation area, namely "light" for an insufficient electrolyte level, "Dark" for an adequate level of electrolyte in the battery is discharged and "Color ball" for an adequate electrolyte level and sufficient Battery state of charge.

A charge level indicator of the type mentioned is known from EP 1120641 known A2. Therein, a ball guide channel is provided for the guide is provided by two balls with different specific weight. The ball guide channel has a length of about three ball diameters. The two balls have different colors from the color of the ball cage are different. In the discharged state of the battery are both Balls at the lower end of the ball guide channel, whereby the upper ball under the tip of the viewing rod comes to rest. If sufficient electrolyte present, is in the observation area of ​​the viewing rod thus the color of the upper ball (for example, red) recognizable. This color indicates that the Battery is discharged. In a middle charge state floating the upper on (lighter) ball and disappears out of sight of the tip of the Viewing rod to the upper end of the ball guide channel, while the lower Ball not float, ie at the lower end of the ball guide channel remains outside of the viewing area of ​​the viewing rod. If there is sufficient Electrolyte level is now the color of the housing (eg. Color) yellow to the viewing surface visible. If the battery is in a good state of charge, floats the lower ball and abuts against the upper, already aufgeschwommene Ball, thereby positioned below the tip of the viewing rod becomes. On the plot is the color of the lower ball (z. B. Green) visible as a sign of a good state of charge.

If the electrolyte level, however fallen, so he lost contact has the level gauge, produced in the plot because of the total reflection to the conical reflection surfaces of the tip of the viewing rod a colorless, bright display, since the incident by the light bar light to the conical reflection surface is totally reflected.

In such a state of charge indicator, the balls thus move on a contact line of the upper boundary wall of the ball guide channel which with an arbitrary cross section, in particular circular or square, can be designed to ensure a defined lateral guidance of the balls have to be. The upper boundary wall of the ball guide channel is through a recess is interrupted, in which projects the tip of the viewing rod. The pointed tip comes this about on the imaginary extension line the upper boundary wall to lie. The angle of the conical reflecting surfaces is significantly greater than the angle of inclination of the inclined ball guide channel. In operation of such a charging status indicator, it is possible that no clear display arise because the ball is not in the desired manner fully float, but the ball guide channel get stuck. It may even happen that in the observation area a partly red and partly green indicator can be seen. In general This can be remedied by knocking on the level gauge. is critical However, if a degradation resulted from a hanging ball remained nil not detected and corrected by shaking or tapping.

The invention is therefore based on the object to display a state of charge indicator of the type mentioned to make störungsunanfälliger.

To achieve this object, a charge status indicator is the aforementioned Type according to the invention characterized in that the top Boundary wall to the conical reflection surface at the transition to cylindrical Shell surface followed continuously.

The invention is based on the realization that a cause of snagging the ball is not in the low by the differences of the specific Weight low buoyancy forces should be sought, for example, not overcome adhesion forces, but primarily in the above pointed tip of the viewing rod with the upper boundary wall of the Ball guide channel formed space in particular by the different Pitch angle of the ball guide channel on the one hand and the conical Reflecting surface of the viewing rod is other hand. This results a step-like for the linear guidance of the floating ball Edge at which the ball can hang when floating. According to the upper boundary wall adjoins now infinitely the conical reflecting surface to. For this purpose, the angle of the conical reflecting surface preferably exactly equal to the pitch angle of the ball guide channel, so that the upper boundary wall with the conical reflection surface aligned. Of course, minor angular deviations of a few angular degrees (<10 °) harmless.

The connection of the upper limiting wall of the conical reflecting surface should be carried out with the smallest possible intermediate space, which in any case less than ¼ of the ball diameter, preferably less than 1.10 of the ball diameter, is. In practice can be a virtually gap-free realize connection.

The construction of the invention is preferably carried out by the fact that the Diameter of the cylindrical outer surface of the viewing rod at the second end formed reduced stepwise so that the level gauge at the Lateral surface step formed at a corresponding annular shoulder of the ball cage be used and so the stepless transition of the conical reflection surface is possible with the upper boundary wall. contrast was provided in the known embodiments, the annular shoulder adapt the ball cage to the slope of the conical reflecting surface, so as to allow the insertion of the defined inspection rod in the ball cage. This resulted in the need to adjust the angle of the conical reflecting surface significantly larger than the pitch angle of the ball guide channel form.

It has also shown that it is expedient for the tip of the viewing rod and bordering on the level gauge edges of the upper boundary wall rounded form, since the balls preferably at sharp edges and Tips stuck.

The invention will in the following with reference to an illustrated in the drawings be explained exemplary embodiment. Show it<dl tsize="8"><dt><b>figure 1a</b></dt><dd>a vertical section through a ball cage with an inserted Tip of the viewing rod</dd><dt><b>figure 1b</b></dt><dd>a stepped horizontal section along the line AA in Figure 1a</dd></dl>

Figure 1a can be one of an electrolyte through which the ball cage 1 recognize which has a cylindrical seat 2 for a visual bar third Of the View rod is at its lower end with a tapered, conical reflection surface 4 provided, which ends in a pointed tip. 5 Of the View bar 3 has a circular cylindrical outer surface 6 that the conical Reflecting surface 4 toward a stage 7 with a reduced diameter is provided. A correspondingly imposed guide 8 is provided in the ball cage. 1

The ball cage 1 has a ball guide channel 9 with a longitudinal axis 10 of the viewing rod 3 forms an angle of approximately 45 °, and by end-side walls 11 is limited in its length. In the ball guide channel 9 is a first ball 12 and a second ball 13. The balls are preferably of the same size and have different colors. The first ball 12 is preferably red, the second ball 13 preferably formed green.

The housing of the ball cage 1 is also preferably colored, in particular yellow running. The first ball 12 has a lower specific weight as the second ball in. 13 With increasing density of the electrolyte thus floats the first ball 12 on first, while the second ball 13 still remains in its lower rest position. Increases the density of the electrolyte loading continued, floating on the second ball. 13

The length of the ball guide channel 9 is three diameters of equal large balls 12. 13

The upper boundary wall 14 has a recess 15 into which the End of the viewing rod 3 projects. The end of the viewing rod 3 is in the recess 15 is inserted so that the tip 9 upwards the conical reflection surface 6 continuously in the upper boundary wall 14 of the ball guide channel 9 passes. As Figure 1b shows a view of the upper boundary wall 14 offers from below, illustrates the upper boundary wall closes 14 to the conical reflection surface 4 on a guide line 16 practically no clearance.

In addition to the continuous and gap-free transition is preferably the angle of the conical reflection surface 4 identical to the pitch angle the upper boundary wall 14 of the ball guide channel 9, so that conical reflection surface 4 and upper boundary wall 14 on the guide line 16 all the way up to the top 5 are aligned.

Figure 1b reveals an edge 17 of the recess 15th This edge 17 and the top 5 can be formed preferably slightly rounded, around sharp edges to avoid the guide line 16 of the balls 12,. 13