Patent Description:
A vehicle usually has a cooling system including a coolant expansion tank. Such a coolant expansion tank has a level sensor arranged to indicate the level of coolant, particularly when the level is low and additional coolant has to be filled into the cooling system.

If the vehicle is driven on a sloping road or is heavily accelerated, the surface of the coolant in the coolant expansion tank can however be inclined relative to the tank such that the level sensor wrongly indicates low level of coolant.

This means that the driver of the vehicle can receive false alarms indicating low level of coolant. The problem may occur for example when driving uphill or downhill, in a roundabout, during cornering or in case of heavy acceleration or deceleration.

Document <CIT> describes a device for regulating the liquid phase of a cooling circuit of a vehicle. A reservoir or degassing box is used for separation of gases from the coolant. A plunger tube submerged in the liquid inside the enclosure is used for reducing the speed of the fluid and minimizing the cascade effect when the coolant entering the enclosure via an inlet.

Document <CIT> discloses a tank with a level sensor.

An objective of the invention is to provide a tank, particularly for a vehicle, which tank can reduce the problem associated with an inclined liquid surface in the tank.

The objective is achieved by a tank according to claim <NUM>.

The invention is based on the insight that by such a tank, a higher level of liquid can be maintained in the tank when the liquid surface is inclined. In case of an inclined liquid surface, air will be trapped in the upper part of the sub space preventing liquid from filling the sub space which in turn results in a higher level of liquid in the space outside the sub space.

Since the tank has a level sensor indicating the level of liquid in the tank, which level sensor is arranged in the space outside the sub space, a higher level of liquid can be maintained at the position for the level sensor when the liquid surface is inclined, thereby avoiding false alarms.

The tank can be any container or limited space containing a liquid where access to the liquid is needed when the liquid level is low, such as a coolant tank, an oil sump of a combustion engine, transmission, etc., and not only when the level of liquid is to be measured. For example, in case the tank has a pump for pumping liquid out from the tank, an inlet of the pump can be arranged in the space outside the sub space for enabling pumping of liquid when the liquid surface is inclined.

According to a further embodiment of the tank, the tank is a coolant tank for a coolant system of a vehicle. The limited space available in an engine compartment of a vehicle often determines the shape of a coolant tank arranged in the engine compartment. The invention is advantageously applied for a coolant tank that is relatively flat (shallow) and/or oblong (long) since such a coolant tank is more sensitive to inclination of the liquid surface.

According to one embodiment of the tank, the enclosure comprises at least one wall extending inside the tank from an upper portion of the housing in a direction towards a lower portion of the housing. Hereby, the enclosure can be integrated in the housing and the tank can be produced in a rational way.

According to a further embodiment of the tank, the enclosure is a tube. Hereby, a cup-like enclosure providing the sub space can be achieved. The tube can have a cross section adapted to the shape of the tank. For example, the cross section can be quadrangular, such as rectangular, or the tube can have a circular cross section. The longitudinal extension direction of the tube, when the tank is horizontal, is preferably substantially vertical.

According to a further embodiment of the tank, a lower end of the tube is slanted, wherein the end surface of the lower end of the tube is inclined with an angle α relative to a horizontal plane such that the end surface slopes downwards in a direction towards a vertical centerline of the housing. Hereby, the efficiency of the sub space trapping air can be further increased. The angle α can be in the range <NUM>°<α<<NUM>°, preferably in the range <NUM><α<<NUM>°.

According to a further embodiment of the tank, the enclosure is arranged at a distance from a side wall of the housing whereby a gap between the enclosure and the side wall is created in a horizontal direction. Hereby, it is secured that liquid can circulate and be collected in the space of the housing outside the enclosure when air is trapped in the sub space.

According to a further embodiment of the tank, the enclosure has a length in a vertical direction which length is less than the distance between a top wall of the housing and a bottom wall of the housing, and a gap is arranged between the enclosure and the bottom wall of the housing. Hereby, it is secured that the space and the sub space are fluidly connected to each other at the same time as the liquid can pass under the enclosure.

For example, the length of the enclosure in the vertical direction can be in a range of <NUM>-<NUM>, preferably <NUM>-<NUM> times the distance between the top wall and the bottom wall of the housing.

According to a further embodiment, the tank has a plurality of said enclosure providing a plurality of said sub space. Hereby, the capacity to trap air can be further increased, and air can be trapped for different inclinations of the liquid surface.

According to a further embodiment of the tank, the enclosures are arranged at a distance from each other creating a gap between adjacent enclosures in a horizontal direction. Hereby, it is secured that liquid can circulate and be collected in the space of the housing outside the enclosures when air is trapped in the sub spaces.

The invention also relates to a vehicle comprising a tank according to the invention, particularly a coolant tank for a coolant system.

Further advantages and advantageous features of the invention are disclosed in the following description and in the claims.

<FIG> shows a tank <NUM> in a schematical view, such as a cooling expansion tank for a vehicle. The tank <NUM> has a housing <NUM> which provides a space <NUM> for a liquid <NUM>, such as a coolant. As an example, and for illustration purposes, in <FIG>, the tank <NUM> is partly cut and approximately half filled with the liquid <NUM> which is indicated with dashed lines.

In <FIG>, the tank <NUM> is arranged horizontally and the liquid surface <NUM> is also horizontal. This is the case for example when the tank <NUM> is installed in a vehicle standing on level ground. See also a cartesian coordinate system X, Y, Z, where all axes are orthogonal to each other, introduced for facilitating the description of the tank. The directions and axes used herein, i.e. the X-axis, Y-axis and the Z-axis, are arranged relative to the tank <NUM> such that when the tank <NUM> is horizontally arranged, the Z-axis is a vertical axis in parallel with a height <NUM> of the tank <NUM>, the X-axis is a horizontal axis in parallel with a length <NUM> of the tank <NUM>, and the Y-axis is a horizontal axis in parallel with a width <NUM> of the tank <NUM>. When using "horizontal", "vertical", etc., herein, reference is made to this horizontal position of the tank as illustrated in <FIG>.

See also <FIG> showing the tank <NUM> in a cross section view from above taken along B-B in <FIG>.

The tank <NUM> further comprising an enclosure <NUM> arranged inside the housing <NUM>. The enclosure <NUM> forms a sub space <NUM> at an upper part <NUM> of the housing <NUM> for trapping air when the liquid surface <NUM> in the tank <NUM> is inclined relative to the housing <NUM>. An upper end <NUM> of the enclosure <NUM> is closed and airtight and a lower end <NUM> of the enclosure <NUM> is open connecting the space <NUM> and the sub space <NUM> fluidly to each other. The tank <NUM> may comprise a plurality of said enclosure <NUM> providing a plurality of said sub space <NUM>. In the example embodiment illustrated in <FIG>, the tank <NUM> has two such enclosures <NUM>, <NUM>' each providing a sub space <NUM>, <NUM>'. The enclosures <NUM>, <NUM>' are arranged at a distance from each other creating a gap <NUM> between adjacent enclosures in the horizontal direction. Each enclosure <NUM> is arranged at a distance from a side wall <NUM> of the housing whereby a gap <NUM> between the enclosure <NUM> and the side wall <NUM> is created in a horizontal direction.

Each enclosure <NUM> comprises at least one wall <NUM> extending inside the tank <NUM> from an upper portion <NUM> of the housing <NUM> in a direction towards a lower portion <NUM> of the housing <NUM>. The enclosure is suitably a tube <NUM>, where the longitudinal extension direction of the tube is substantially vertical. The tube <NUM> is closed in the upper end <NUM> and open in the lower end <NUM>.

As shown in <FIG>, the enclosures <NUM>, <NUM>' defining the sub spaces <NUM>, <NUM>' may have quadrangular cross sections, but other shapes are also possible.

<FIG> is a cross section view showing a variant of the tank where the enclosures <NUM>, <NUM>' have circular cross sections.

Preferably, the lower end <NUM> of the tube <NUM> is slanted, such that the end surface <NUM> of the lower end <NUM> of the tube <NUM> is inclined with an angle α relative to a horizontal plane, and the end surface <NUM> slopes downwards in a direction towards a vertical centerline <NUM> of the housing <NUM>. The horizontal plane is in parallel with the plane defined by the X-axis and the Y-axis. The vertical centerline <NUM> is in parallel with the Z-axis.

In other words; the end surface <NUM> of the lower end <NUM> of the tube <NUM> is inclined such that a part <NUM> of the end surface <NUM> arranged with the smallest distance <NUM> to the lower portion <NUM> is arranged closest to the vertical centerline <NUM> of the housing <NUM>, and a part <NUM> of the end surface <NUM> arranged with the greatest distance <NUM> to the lower portion <NUM> is arranged furthest from the vertical centerline <NUM>.

The enclosure <NUM> suitably has a length <NUM> in a vertical direction which length is less than the distance between a top wall <NUM> of the housing <NUM> and a bottom wall <NUM> of the housing <NUM>, and a gap <NUM> is arranged between the enclosure <NUM> and the bottom wall <NUM> of the housing <NUM> in a vertical direction.

The tank has a level sensor <NUM> indicating the level of liquid <NUM> in the tank <NUM>. Such a level sensor <NUM> is arranged in the space <NUM> outside the sub space <NUM>.

<FIG> shows the tank <NUM> illustrated in <FIG> when the liquid surface <NUM> is inclined relative to the horizontal housing <NUM>. The liquid surface <NUM> is inclined with an angle β relative to the horizontal axis X. Such an inclination can arise due to acceleration or deceleration of the tank (i.e. due to g-forces), for example when the tank <NUM> is installed in a vehicle driving along a road.

The sub space <NUM> of the enclosure <NUM> to the right is filled with air <NUM> preventing liquid <NUM> from reaching the sub space <NUM>. The actual liquid surface <NUM> is indicated with a solid line and further, a dotted line indicates the liquid surface <NUM>' or level that would have been present in case there was no enclosure trapping air. The increased level of liquid <NUM> due to the trapped air is the difference Δ between the solid line and the dotted line.

<FIG> shows the tank <NUM> illustrated in <FIG> when the tank <NUM> is inclined with an angle β relative to the horizontal axis X, whereas the liquid surface <NUM> is in parallel with the horizontal axis X. This means the liquid surface <NUM> is inclined with an angle β relative to the housing <NUM>. Such an inclination of the tank <NUM> can arise when the tank <NUM> is installed in a vehicle driving along a sloping road.

In the same way as previously explained with reference to <FIG>, the sub space <NUM> of the enclosure <NUM> to the right is filled with air <NUM> preventing liquid <NUM> from reaching the sub space <NUM>. The actual liquid surface <NUM> is indicated with a solid line and further a dotted line indicates the liquid surface <NUM>' or level that would have been present in case there was no enclosure trapping air. The increased level of liquid <NUM> due to the trapped air is the difference Δ between the solid line and the dotted line.

<FIG> show in perspective views from above and below, respectively, a further example embodiment of the tank constituting a vehicle coolant expansion tank. Primarily, the features unique for this example embodiment are described. As it regards previously described features, reference is made to the description hereinabove. Further, same reference numerals have been used for similar or equal components.

The expansion coolant tank <NUM> is relatively flat (shallow) in comparison to the length (and width) of the tank. The limited space available in an engine compartment of a vehicle often determines the shape of a coolant tank arranged in the engine compartment. Such a shallow coolant tank can be more sensitive to inclination of the liquid surface resulting in false low coolant level warnings.

The housing <NUM> of the tank <NUM> can be made from an upper portion <NUM>, such as a cap, and a lower portion <NUM>, such as a container. The upper portion and lower portion refer to the orientation of the tank <NUM> when installed in a vehicle. As appears from <FIG>, the cap <NUM> has an opening <NUM> for filling of coolant into the tank <NUM>. As appears from <FIG>, the container <NUM> has connections <NUM> for connecting the tank fluidly to a coolant system of a vehicle. Further, the tank <NUM> has brackets <NUM> for attachment of the tank <NUM> in the engine compartment.

The cap <NUM> and the container <NUM> are suitably provided with flanges <NUM>, <NUM> for connecting the cap <NUM> and the container <NUM> to each other in a waterproof way, permanently or in a divisible way.

<FIG> shows the cap <NUM> from below. On the inside of the cap <NUM>, walls <NUM> can be arranged to divide the housing <NUM> into several compartments <NUM> to counteract too fast transport and splash of coolant when the tank <NUM> is subjected to acceleration or deceleration. In such a case, some openings <NUM> have to be arranged in the walls <NUM> to enable coolant to flow, with a reduced speed instead, in the housing <NUM> which provides one continuous space for the coolant.

In the example embodiment illustrated in <FIG>, the tank <NUM> is provided with two enclosures <NUM> forming two sub spaces <NUM> in the tank <NUM>. For the two compartments <NUM> to the right in <FIG>, one enclosure <NUM> is arranged in each compartment <NUM> for trapping air when the liquid surface in the tank <NUM> is inclined relative to the housing <NUM>. Each enclosure <NUM> is designed as a tube extending from the cap <NUM> towards the container <NUM> when the cap and container are connected to each other.

<FIG> shows the container <NUM> from above. On the inside of the container <NUM>, in the same way as previously described for the cap <NUM>, walls <NUM>' can be arranged in the bottom of the container <NUM> to divide the housing <NUM> into the several compartments <NUM>' to counteract too fast transport and splash of coolant when the tank is subjected to acceleration or deceleration. The walls <NUM> of the cap <NUM> and the walls <NUM>' of the container <NUM> are suitably designed such that when the cap <NUM> and the container <NUM> are connected, a respective cap wall <NUM> and a respective container wall <NUM>' together form a complete wall corresponding to the height of the housing <NUM>. In such a case, some openings <NUM> may have to be arranged in the container walls <NUM>' as well, allowing coolant to be transported with a reduced speed.

In the example embodiment illustrated in <FIG>, for the two compartments <NUM>' to the right, one enclosure <NUM> is received in each compartment <NUM>' when the cap <NUM> and the container <NUM> are connected to each other. See also <FIG>.

<FIG> shows a cross section view of the tank <NUM> when the liquid surface <NUM> is inclined relative to the housing <NUM>. The liquid surface <NUM> is inclined relative to the horizontal housing <NUM>. The liquid surface <NUM> is inclined with an angle β relative to the horizontal axis X. Such an inclination can as already mentioned arise due to acceleration or deceleration of the tank <NUM> (i.e. due to g-forces), for example when the tank <NUM> is installed in a vehicle driving along a road. Since the sub space <NUM> of each enclosure <NUM> is filled with air <NUM> preventing liquid <NUM> from reaching the sub space <NUM>, the level of liquid reaches the level sensor <NUM>.

<FIG> shows a vehicle <NUM> provided with a tank <NUM> according to the invention used as an expansion coolant tank.

Claim 1:
A tank (<NUM>) having a housing (<NUM>) which provides a space (<NUM>) for a liquid (<NUM>), characterized in that an enclosure (<NUM>) forming a sub space (<NUM>) is arranged inside the housing (<NUM>) at an upper part (<NUM>) of the housing for trapping air when the liquid surface (<NUM>) in the tank is inclined relative to the housing (<NUM>), an upper end (<NUM>) of the enclosure (<NUM>) being closed and airtight and a lower end (<NUM>) of the enclosure (<NUM>) being open connecting the space (<NUM>) and the sub space (<NUM>) fluidly to each other, wherein the tank (<NUM>) has a level sensor (<NUM>) indicating the level of liquid (<NUM>) in the tank, the level sensor (<NUM>) being arranged in the space (<NUM>) outside the sub space (<NUM>).