FR3093178A3 - Device for measuring a liquid level in a tank, pump-gauge module, corresponding tank and vehicle - Google Patents

Abstract

The invention relates to a device for measuring a liquid level in a vehicle tank (2), the tank (2) comprising at least two cavities interconnected and staggered, including a first cavity (21). and a second cavity (22), the device comprising: - at least two gauges including a first gauge associated with the first cavity (21) and a second gauge associated with the second cavity (22), each gauge carrying out a measurement of the level of liquid for a height range (H1, H2) of liquid dedicated to the gauge and located in the cavity associated with it, the gauges being connected to each other by an electrical circuit, and - a common electrical output for the entire electrical circuit and delivering an output signal reflecting the measurement of each gauge. Figure for the abstract: figure 1

Description

Device for measuring a level of liquid in a tank, pump-gauge module, corresponding tank and vehicle

The invention relates to the field of devices for measuring a level of liquid in a tank and in particular in a fuel tank or in an oil tank of a motor vehicle. The invention also relates to a pump-gauge module of a vehicle fuel tank, a tank and a vehicle comprising such a device.

Automakers design vehicle fuel tanks with complex shapes that fit the space available in the vehicle. This makes it possible, in particular for a fuel tank, to increase the volume of the tank and therefore the range of the vehicle while optimizing the space in the vehicle. Tanks are equipped with a device for measuring the level of liquid in the tank, called a gauging device, to calculate the volume of liquid present in the tank. These devices comprise an arm terminated by a float, the arm being articulated on a support comprising a gauge consisting for example of a variable resistor, the rotation of the arm relative to the support modifying the value of the variable resistor. The gauge is integrated into an electrical circuit delivering an output signal reflecting the value of the variable resistor and therefore reflecting the level of liquid in the reservoir. For certain shapes of complex tanks, a gauging device equipped with a single arm is not sufficient to measure all the levels necessary for calculating the volume of fuel. This is true in particular for tanks comprising at least two cavities including a first low cavity and a second high cavity, the two cavities being interconnected and staggered in step. The gauging device must then be capable of measuring liquid levels in a first liquid height range located in the first cavity and in a second liquid height range located in the second cavity. However, a gauge arm located in the first lower cavity makes it possible to measure all the liquid levels in the first height range but not in the second height range because the travel of the gauge arm is limited by an upper face of the first cavity. Conversely, a gauge arm located in the second high cavity makes it possible to measure all the liquid levels in the second height range but not in the first height range because the stroke of the gauge arm is limited by an underside of the second cavity. Conventionally, the resistive gauging devices as described above are integrated into a pump-gauge module also comprising a fuel pump. These modules are bulky. A solution for measuring liquid levels in the first height range and in the second height range is to install two pump-gauge modules, one in the first cavity, the other in the second cavity. However, this solution is expensive, it reduces the volume available for the fuel in the tank and involves a modification of the design of the tank to integrate the second pump-gauge module.

The invention proposes a solution aimed at overcoming the aforementioned drawbacks. An object of the invention is to provide a device for measuring the level of liquid in a tank capable of measuring liquid levels in a first liquid height range located in a first cavity and in a second liquid height range located in a second cavity, the two cavities being interconnected and staggered in step, the device being inexpensive, not bulky and not modifying the design of the reservoir.

The invention relates to a device for measuring a level of liquid in a vehicle tank, the tank comprising at least two cavities connected to one another and staggered in step, including a first cavity and a second cavity, the device comprising:
- at least two gauges including a first gauge associated with the first cavity and a second gauge associated with the second cavity, each gauge carrying out a measurement of the liquid level for a liquid height range dedicated to the gauge and located in the cavity which associated with it, the gauges being interconnected by an electrical circuit, and
- a common electrical output for the entire electrical circuit and delivering an output signal reflecting the measurement of each gauge.
By gauge is meant a sensor making it possible to perform a measurement and delivering the measurement in the form of an electrical signal. The sensor is for example an ohmic conductor whose resistance value varies linearly depending on the position of a cursor which moves with the level to be measured, an optical sensor, an ultrasonic sensor, or a sensor using the capacitive effect. Liquid level means a height of liquid measured from a reference height. The term “two cavities interconnected and staggered in stair step” means two cavities including a first low cavity and a second high cavity; that is to say that the upper face of the first cavity is lower than the upper face of the second cavity and that the lower face of the first cavity is lower than the lower face of the second cavity.
Such a device is capable of measuring liquid levels in a first liquid height range located in the first cavity using the first gauge and in a second liquid height range located in the second cavity using the second gauge. Since the gauges are interconnected by an electrical circuit delivering a single output signal reflecting the measurement of each gauge, it is possible to retain the existing connection, initially provided for a single gauge, on the dashboard. This makes it possible to keep the existing structure of the vehicle as much as possible and therefore to limit the costs of implementing the invention in a vehicle.

According to the invention, the device may further comprise, for each gauge, an arm terminated by a float, the arm being articulated around an axis of rotation on a support comprising the gauge, the rotation of the arm relative to the support modifying gauge measurement. As the rotation of the arm relative to the support changes the measurement of the gauge, it therefore changes the output signal. Such an arm mechanism terminated by a float and articulated on a support comprising a gauge is widely used in devices for measuring the level of liquid in a vehicle tank, it is therefore a well-controlled and reliable mechanism. Also, it is inexpensive.

According to the invention, the respective axes of rotation of the arms can extend in two respective directions forming between them an angle α comprised between π/4 and π radians. This makes it possible to orient one arm so that it is located in a cavity and to orient the other arm so that it is located in the other cavity.

According to the invention, the gauges can be connected in series. This is a solution for connecting the gauges together by an electrical circuit so as to obtain a common electrical output for the entire electrical circuit, the electrical output delivering an output signal reflecting the measurement of each gauge.

According to the invention, each gauge can include a variable resistor. Such a resistive gauge is widely used in measuring devices, so it is a well-controlled and reliable gauge. Furthermore, it is inexpensive.

According to the invention, the variable resistor of each gauge can be carried by a component specific to it. Thus, the gauges can be separate elements, identical to the gauges used in current devices for measuring the level of liquid in a tank.

According to the invention, the variable resistors of at least two gauges can be carried by the same component, the component comprising a resistive track divided into at least two portions, each portion constituting the variable resistor of one of the gauges. This solution makes it possible to use only one component to produce the two gauges. This can make it possible to reduce the size of the measuring device.

According to the invention, each gauge can return a zero signal for a liquid level outside the liquid height range dedicated to it. The first gauge measures the liquid level when this level is located in a first liquid height range dedicated to the first gauge. The second gauge measures the liquid level when this level is located in a second liquid height range dedicated to the second gauge. This makes it possible to dissociate the measurements of each gauge to simplify the interpretation of the output signal.

The invention also relates to a pump-gauge module of a vehicle fuel tank comprising a measuring device according to the invention.

The invention also relates to a vehicle tank comprising a measuring device according to the invention. The tank is for example a fuel tank and the level of liquid measured by the measuring device is then the level of fuel present in the tank.

The invention also relates to a vehicle comprising a measuring device according to the invention.

Other characteristics and advantages of the present invention will appear more clearly on reading the following detailed description of embodiments of the invention given by way of non-limiting example and illustrated by the appended drawings, in which:

schematically represents a vertical sectional view of a tank according to one embodiment of the invention;

schematically represents a perspective view of a pump-gauge module of the reservoir of FIG. 1; and

schematically represents an electrical circuit interconnecting gauges of a device for measuring the level of liquid in a tank according to one embodiment of the invention.

Figures 1 and 2 are oriented according to an orthonormal frame comprising a longitudinal axis (x) horizontal pointing forward, a transverse axis (y) horizontal pointing left and a vertical axis (z) aligned with the field of gravity and pointing up.

FIG. 1 represents a fuel tank 2 of a vehicle according to one embodiment of the invention. Reservoir 2 has a complex shape and comprises two cavities including a first cavity 21 and a second cavity 22. The first cavity 21 comprises a lower face 211 and an upper face 212 and the second cavity comprises a lower face 221 and an upper face 222 The two cavities 21 and 22 are interconnected and staggered, the first cavity 21 being low and the second cavity 22 being high. Thus, the upper face of the first cavity 21 is lower than the upper face of the second cavity 22; and the lower face of the first cavity 21 is lower than the lower face of the second cavity 22. In the example of FIG. 1, the first cavity 21 and the second cavity 22 communicate on a portion 20 of the reservoir located between the height of the lower face 221 of the second cavity 22 and the height of the upper face 212 of the first cavity 21. This notably allows the two cavities to communicate.

Referring to Figures 1 and 2, the tank 2 comprises a pump-gauge module 8 according to one embodiment of the invention. The pump-gauge module 8 comprises an electric fuel pump designed to supply fuel to the engine with a controlled pressure and flow, the pumping flow and pressure being directly related to the electrical consumption of the pump. The pump-gauge module 8 also comprises a device 1 for measuring the level of fuel in the tank 2.

The device 1 comprises two supports including a first support 61 and a second support 62 as well as two gauges including a first gauge 11 placed in the first support 61 and a second gauge 12 placed in the second support 62. The first support 61 is fixed on a first lateral face 81 of the pump-gauge module 8. The second support 62 is fixed on a second lateral face 82 of the pump-gauge module 8. The first face 81 and the second face 82 are two consecutive faces of the pump-gauge module 8 .

As a variant, the supports 61 and 62 can be fixed to an element other than the pump-gauge module. For example, the supports 61 and 62 can be fixed on internal walls of the tank 2.

The first gauge 11 is associated with the first cavity 21 and the second gauge 12 is associated with the second cavity 22. The first gauge 11 measures the fuel level when this level is located in a first liquid height range H1 dedicated to the first gauge 11 and located in the first cavity 21. The second gauge 12 measures the fuel level when this level is located in a second liquid height range H2 dedicated to the second gauge 12 and located in the second cavity 22. The first height range H1 extends vertically between the height of the lower face 211 of the first cavity 21 up to the height of the lower face 221 of the second cavity 22. The second height range H2 extends vertically between the height from the lower face 221 of the second cavity 22 up to the height of the upper face 222 of the second cavity 22.

The device 1 further comprises two arms including a first arm 41 terminated by a first float 51 and a second arm 42 terminated by a second float 52. The first arm 41 is articulated on the first support 61 comprising the first gauge 11. The first arm 41 is in pivot connection with the first support 61 and is rotatable relative to the first support 61 around a first axis A1 orthogonal to the first face 81. The second arm 42 is articulated on the second support 62 comprising the second gauge 12. The second arm 42 is in pivot connection with the second support 62 and is rotatable relative to the second support 62 around a second axis A2 orthogonal to the second face 82.

The first float 51 extends in a direction parallel to the first axis A1 and the second float 52 extends in a direction parallel to the second axis A2.

The first float 51 is free to move to the different heights of the first height range H1 thanks to the rotation of the first arm 41 around the first axis A1. Thus, when the level of liquid in the tank is in the height range H1, the first float 51 floats on the surface of the liquid in the tank and imposes an angular position on the first arm 41 with respect to the first axis A1. Thus, the angular position of the first arm 41 gives information as to the level of liquid in the tank when the latter is situated in the first range of height H1.

Similarly, the second float 52 is free to position itself at the different heights of the second range of height H2 thanks to the rotation of the second arm 42 around the second axis A2. Thus, when the level of liquid in the tank is in the height range H2, the second float 52 floats on the surface of the liquid in the tank and imposes an angular position on the second arm 42 with respect to the second axis A2. Thus, the angular position of the second arm 42 gives information as to the level of liquid in the tank when the latter is situated in the second range of height H2.

The first axis A1 of rotation of the first arm 41 forms an angle α with the second axis A2 of rotation of the second arm 42. By way of illustration and in no way limiting, the angle α has a value of π/2 radians in the example represented . According to the invention, the angle α can be between π/4 and π radians. Such angle values α make it possible to orient the arms in the cavities whatever the geometry of the reservoir.

The first gauge 11 and the second gauge 12 are sensors delivering an electrical signal giving information about the level of liquid measured. By way of illustration and in no way limiting, each gauge 11 or 12 can be:
- a variable ohmic resistor, i.e. an ohmic conductor whose resistance value varies linearly according to the liquid level,
- an optical sensor, for example comprising light ray detection windows distributed over the entire extent of the height range of the liquid to be measured,
- an ultrasonic sensor, or
- a sensor using the capacitive effect.

The first gauge 11 and the second gauge 12 are interconnected by an electric circuit. The electrical circuit comprises a common electrical output for the entire electrical circuit and delivers an output signal reflecting the measurement of the first gauge 11 and the measurement of the second gauge 12. In particular, from the output signal, it is possible to knowing the information about the measured liquid level transmitted by the first gauge 11 as well as the information about the measured liquid level transmitted by the second gauge 12.

The first gauge 11 and the second gauge 12 can be connected in series or in parallel.

The common output 30 can be directly connected to the dashboard of the vehicle without modifying the connections compared to the dashboards of the prior art.

FIG. 3 schematically represents an electrical circuit 3 interconnecting first gauge 11 and second gauge 12. In the example illustrated in FIG. 3, first gauge 11 and second gauge 12 respectively comprise a first variable resistor 71 and a second variable resistor 72. The first variable resistor 71 and the second variable resistor 72 are connected in series. The electrical circuit 3 comprises a common output 30 delivering an output signal. The circuit behaves according to Ohm's law with the ohmic resistance value being the sum of the values of the first variable resistor 71 and of the second variable resistor 72.

The range of values of the first variable resistor 71 and the range of values of the second variable resistor 72 are chosen so as to be able to deduce from the output signal the value of the first variable resistor 71 and that of the second variable resistor 72 For example, the ranges of values do not overlap.

The rotation of the first arm 41 with respect to the first axis A1 modifies the value of the first variable resistor 71. The value of the first variable resistor 71 is therefore correlated to the angular position of the first arm 41. Thus, the value of the first resistor variable 71 gives information as to the level of liquid in the reservoir when the latter is situated in the first range of height H1. In particular, in the example, there is an affine relationship between the value of the first variable resistor 71 and the level of liquid in the reservoir when the latter is in the first range of height H1.

The rotation of the second arm 42 with respect to the second axis A2 modifies the value of the second variable resistor 72. The value of the second variable resistor 72 is therefore correlated to the angular position of the second arm 42. Thus, the value of the second resistor variable 72 gives information as to the level of liquid in the reservoir when the latter is situated in the second range of height H2. In particular, in the example, there is an affine relationship between the value of the second variable resistor 72 and the level of liquid in the tank when the latter is in the second range of height H2.

In the example shown, the variable resistor 71 or 72 of each gauge 11 or 12 is carried by a component which is specific to it. Indeed, a component comprises the resistive track of the first variable resistor 71 and is placed in the first support 61 and another component comprises the resistive track of the second variable resistor 72 and is placed in the second support 62. The components are therefore distinct.

As a variant, the variable resistors 71 and 72 of the two gauges 11 and 12 can be carried by the same component. The component then comprises a resistive track divided into two portions, a first portion constituting the first variable resistor 71 of the first gauge 11 and a second portion constituting the second variable resistor 72 of the second gauge. This variant makes it possible to condense the measuring device. Furthermore, when the first portion and the second portion form a continuous resistive track, there is continuity in the resistance values measured by the first gauge 11 and by the second gauge 12, which can simplify the relationship which exists between the signal outlet and the fluid level in the reservoir.

Each gauge returns a zero signal for a liquid level outside its dedicated liquid height range. Thus, for the first gauge 11, the value of the first variable resistor 71 is zero when the liquid level is outside the first height range H1 and, for the second gauge 12, the value of the second variable resistor 72 is zero when the liquid level is outside the second height range H2.

It will be understood that various modifications and/or improvements obvious to those skilled in the art can be made to the various embodiments of the invention described in the present description without departing from the scope of the invention defined by the appended claims.

Claims (10)

Device (1) for measuring a level of liquid in a tank (2) of a vehicle, the tank (2) comprising at least two cavities connected to one another and staggered in step, including a first cavity (21) and a second cavity (22), the device (1) being characterized in that it comprises:
- at least two gauges including a first gauge (11) associated with the first cavity (21) and a second gauge (12) associated with the second cavity (22), each gauge performing a measurement of the liquid level for a height range (H1, H2) of liquid dedicated to the gauge and located in the cavity associated with it, the gauges (11, 12) being connected to each other by an electric circuit (3), and
- an electrical output (30) common for the entire electrical circuit (3) and delivering an output signal reflecting the measurement of each gauge (11, 12). Measuring device (1) according to Claim 1, characterized in that it further comprises, for each gauge (11, 12), an arm (41, 42) terminated by a float (51, 52), the arm (41 , 42) being articulated around an axis (A1, A2) of rotation on a support (61, 62) comprising the gauge (11, 12), the rotation of the arm (41, 42) relative to the support (61, 62) modifying the measurement of the gauge (11, 12). Measuring device (1) according to Claim 2, characterized in that the respective axes (A1, A2) of rotation of the arms (41, 42) extend in two respective directions forming between them an angle (α) comprised between π/ 4 and π radians. Measuring device (1) according to any one of the preceding claims, characterized in that the gauges (11, 12) are connected in series. Measuring device (1) according to any one of the preceding claims, characterized in that each gauge (11, 12) comprises a variable resistor (71, 72). Measuring device (1) according to Claim 5, characterized in that the variable resistor (71, 72) of each gauge (11, 12) is carried by a component which is specific to it. Device (1) according to any one of the preceding claims, characterized in that each gauge (11, 12) returns a zero signal for a level of liquid outside the height range (H1, H2) of liquid which is dedicated to it . Pump-gauge module (8) of a vehicle fuel tank comprising a measuring device according to any one of Claims 1 to 7. Vehicle tank (2) comprising a measuring device according to any one of claims 1 to 7. Vehicle comprising a measuring device according to any one of Claims 1 to 7.