GB2486459A

GB2486459A - Wading vehicle depth measurement apparatus

Info

Publication number: GB2486459A
Application number: GB1021297.5A
Authority: GB
Inventors: Thuy-Yung Tran; Edward Hoare; Nigel Clarke
Original assignee: Land Rover UK Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2010-12-15
Filing date: 2010-12-15
Publication date: 2012-06-20
Also published as: GB201021297D0

Abstract

A wading vehicle 100 includes a capacitive or resistive sensor to determine water depth D. The sensor may be a pair of elongate electrodes 114 which enable a number of discrete depths to be measured or a continuous change in water level. The sensor 114 may be positioned below an air intake 112. The sensor 114 may be activated by a parking distance control sensors 126 configured to detect the presence of water adjacent the vehicle. Also claimed is a method of determining the angular orientation of a vehicle from information received from a number of water level sensors, fig 8.

Description

Wading vehicte depth measurement apparatus The present invention is concerned with an apparatus for measuring the water level relative to a vehicle body. More particularly, the present invention is concerned with the measurement of the water level of a wading vehicle and providing such information to a driver of the vehicle.

Off road vehicles are often required to travel through water to reach their intended destination. Travel through deep water (typically up to about 0.75m in depth) is known as "wading". Known off-road vehicles are design to wade, and comprise suitably sealed closures to avoid ingress of water into the passenger compartment.

The engine air intake is positioned at an elevated position (normally directly in front of and below the windscreen) to prevent water being ingested into the engine, and this intake will often dictate the maximum level of water relative to the body that the vehicle can wade through without risking water ingestion and engine damage.

Prior art methods of determining if the water level is safe to wade through include referring to depth gauges, e.g. permanent graduated poles situated within the water in the case of fords and measurement of the depth by the driver using a partially submerged stick or pole.

The former method requires such a gauge to be present, and the latter method involves the driver exiting the vehicle. The latter method in particular will often not reveal the deepest point unless the driver wades in, which is undesirable and dangerous.

Both methods only reveal the absolute depth of the water (from the ground to the water surface). This is often not sufficient to make an accurate assessment of the vehicle's capability to pass. The knowledge that the driver requires is, instead, what the water level is relative to a point on the vehicle body (e.g. the air intake). The distance between the bottom of the vehicle tyres and the air intake is variable (due to suspension travel, tyre pressure variations etc) and as such with known methods the driver must take account of a potential margin of error in making his decision. This is undesirable as the driver may decide not to proceed through water which the vehicle is, in fact, capable of wading through.

An aim of the present invention is to at least mitigate the above mentioned problems.

According to a first aspect of the invention there is provided a wading vehicle water level measurement apparatus comprising a vehicle component having a capacitive or resistive water level sensor attached to an exposed surface in use.

By exposed surface, we mean a surface which is not only contactable by the environment in which the vehicle is immersed, but is immersed to a level representative of the level of fluid external to the vehicle. In other words, when the vehicle is wading, the level of fluid above the surface must be the same as the level of fluid external to the vehicle. For example, extemal surfaces of components in the engine bay are usually exposed surfaces. Preferably the sensor is positioned on a body component; i.e. a component which is substantially fixed in position relative to the engine air intake.

Preferably the sensor is configured to detect a plurality of water levels. More preferably the sensor is configured to detect the extent of the water level either continuously or in a plurality of discrete levels. Preferably there are at least five such levels.

Resistive or capacitive sensors rely on the electrical properties of a substance disposed between two electrodes. The resistance of water is lower than that of air (for a resistive sensor), and the dielectric constant of water is many times higher than air (for a capacitive sensor).

To provide a continuous measurement, the sensor may comprise a pair of elongate electrodes oriented in a vertical sense (with respect to the vehicle local coordinate system) and the water level may be determined by measuring the resistance / capacitance across the sensor electrodes. The change in water level will be generally proportional to the change in resistance or capacitance.

Ahernatively, the sensor may provide a discrete, piecewise, measurement. In other words the sensor may comprise an array of electrode pairs oriented in the vertical sense, and the water level determined by a change in resistance / capacitance at the highest electrode pair. The sensor may comprise a single electrode on one side of the sensor and a plurality of electrodes on the opposing side, with the resistance or capacitance being sequentially measured between each of the plurality and the single opposing electrode.

Preferably, the sensor is positioned below the lowest water-critical component. For example, the sensor may be positioned below the engine air intake.

Preferably, the sensor is activated by a wading sensor which detects the presence of water at a low level on the vehicle. The wading sensor may be a PDC parking distance control) sensor configured to detect the presence of water.

Preferably the vehicle comprises an angular orientation sensor such as an accelerometer or gyroscope and a water level detection system comprising a memory and a processor, in which the memory is configured to store a water level measurement from the water level sensor and a vehicle orientation from the angular orientation sensor, the memory further storing software executable by the processor to determine a water level on the vehicle at a position spaced from the water level sensor.

Advantageously, the sensor can therefore be placed at a positioned spaced apart from e.g. the air intake should packaging and / or functional requirements dictate.

The sensors may be positioned on the front subframe, radiator support pack, bumper beam, wheel arch liner, suspension knuckle, lower arms or similar components.

Muhiple sensors may be positioned across more than one component to measure water level at different heights in the vehicle body local coordinate system.

Alternatively the sensor may be provided on a dedicated component such as an elongate member extending vertically in the car body local coordinate system.

According to a second aspect of the invention there is provided a vehicle comprising an apparatus according to the first aspect.

According to a third aspect of the invention there is provided a vehicle having a wading vehicle water level measurement apparatus comprising a plurality of vehicle mounted capacitive or resistive water level sensors positioned at different transverse and / or longitudinal positions in the vehicle body local coordinate system.

Preferably the sensors are configured to detect a plurality of water levels. By comparing the water level at different positions on the body the angular position of the body whilst wading can be determined.

According to a fourth aspect of the present invention there is provided a vehicle comprising a wading water level sensor, a vehicle angular orientation sensor, a processor and a memory, the memory having a program loaded thereon configured to, when run by the processor, calculate an estimated water level at a predetermined distance from the vehicle using a reading from the wading water level sensor and a reading from the angular orientation sensor.

Advantageously, the driver can then be warned via a display if the estimated level ahead of the vehicle is too deep for the vehicle to travel in.

Preferably the program is configured to calculate the estimated water level at a plurality of distances from the vehicle in the same direction, preferably in the direction of travel. In addition, the program may be configured to calculate the estimated water level in a plurality of different directions, for example using a roll sensor reading as well as a pitch sensor reading.

According to a fifth aspect of the invention there is provided a method of estimating a water level ahead of a wading vehcile comprising the steps of providing a vehicle having a water level sensing apparatus and an angular orientation sensor, at least partially immersing the vehicle, measuring the water level using the water level sensing apparatus, S measuring the vehicle angular orientation using the angular orientation sensor, calculating an estimated water level at a predetermined distance from the vehicle using the water level and the angular orientation.

Preferably the method includes the step of communicating the estimated depth to the driver via a display.

An example apparatus in accordance with the present invention will now be described with reference to the accompanying figures in which: FIGURE 1 is a schematic side view of a wading off-road vehicle comprising a first apparatus according to the present invention, FIGURE 2 is a detail view of a part of the vehicle of figure 1, FIGURE 3 is a schematic view of a first apparatus in accordance with the present invention, FIGURE 4 is a schematic view of an alternative sensor for the apparatus of figure 3, FIGURE 5 is a schematic view of another alternative sensor for the apparatus of figure FIGURE 6 is a schematic side view of a wading off-road vehicle comprising a second apparatus according to the present invention, FIGURE 7 is a schematic side view of a wading off-road vehicle comprising a third apparatus according to the present invention, and, FIGURE 8 is a schematic side view of a wading off-road vehicle comprising a fourth apparatus according to the present invention.

Referring to figure 1, a vehicle 100 comprises a body 102, a left front wheel 104 and a left rear wheel 106. The wheels 104, 106 (and their counterparts on the right hand side of the vehicle) are connected to the body 102 via a suspension (not shown).

The wheels can move relative to the body to define a ride height R between the lowermost point of the tyres (where they contact the ground) and the lowermost point on the body. The ride height R varies with suspension travel and may be varied by the driver (for example to move from a on-road mode when R is small to an off-road mode when R is large).

The body 102 comprises a windscreen 108 and a bonnet (or hood) 110 covering an engine bay. On the body 102 between the windscreen 108 and the bonnet 110 there is defined and engine intake orifice 112. The orifice is connected to the air fiher and intake manifold of the engine (not shown). The intake orifice 112 is positioned at a height H from the lowermost part of the body 102.

The vehicle 100 is shown wading through water 12 at a water depth D from a ground level 10. The water depth D should be distinguished from the water level represented by L which is the level of the water above the lowermost point on the body 102.

It will be noted that although D can be measured (by a roadside gauge or a measuring stick), the distance L is unknown (as R can vary). In order to know whether the vehicle can be taken through the water, the distance between the intake orifice 112 of the water level 10 needs to be determined.

Referring to figure 2, the front section of the vehicle 100 is shown. An level sensing apparatus 114 according to the present invention is shown in hidden line and is positioned within the engine bay on the engine bay bulkhead.

Turning to figure 3, the level sensing apparatus 114 is shown in schematic detail. The apparatus 114 comprises a resistive sensor 116 having a first conductive plate 118 and a second conductive plate 120 spaced therefrom. The plates are parallel and offset to define a gap 122 therebetween. Each plate 118, 120 is connected to an electrical circuit 124 which is configured to measure the resistance of the sensor 116 (for example by measuring the vohage across the plates and the current in the circuit).

The plates 118, 120 are elongate and as the vehicle wades are at least partially submersed in water 12. Because the conductivity of water is higher than that of air, the resistance of the sensor 116 will drop with increasing water level. There will be a linear relationship between level L and the resistance of the sensor 116. As such, once the sensor 116 is calibrated, the level L can be detected and the information provided to the vehicle systems and the driver.

Turning to figure 4, an ahemative sensor 216 is shown which comprises a series of electrode plate pairs each comprising a first electrode 218 and a second electrode 220.

The pairs of plates are spaced in the vehicle height direction.

In one embodiment, the resistance of the electrode pairs are simultaneously measured.

It will be noted that the electrode pairs which are fully submerged will have a significantly lower resistance than the pairs that are not. Therefore the water level L can be measured by the height of the highest electrode pair with low resistance.

It will be noted that one of the electrode pairs may be partially submerged, and interpolation of resistance against the height of that electrode pair may be used to make the level measurement more accurate.

In an alternative embodiment, only one electrode pair at a time is measured, for example using a multiplexer. This will simplify the necessary circuitry.

An advantage of the embodiment of figure 4 is that because the system reslies on discretely positioned electrode pairs, changes in the properties of the water will not significantly affect the level measured.

Turning to figure 5, another alternative sensor 316 is shown. The sensor 316 comprises a first electrode plate 318 and a series of second electrode plates 320. The sensor 316 works in a similar manner to the sensor 216, except that only the plates 320 need to be measured alternately (e.g. multiplexed).

It will be noted that all of the above embodiments may be used in a capacitive sense-that is the capacitance of the pairs of plates may be measured instead of the resistance on the assumption that the dielectric constant of water and air are different (as are their conductivity).

Turning to figure 6, the vehicle is shown having a measurement apparatus 114 as well as a PDC (parking distance control) sensor 126 mounted on the front of the vehicle 100.

The PDC sensor can be used to detect the presence of water 12 (the water 12 will affect the performance of the PDC sensor) and this can trigger activation of the apparatus 114. Therefore the apparatus 114 can be dormant for most of the time except for when the vehicle 100 is wading.

Referring to figure 7 a vehicle 400 has an apparatus 414 similar to the apparatus 114 but positioned at a horizontal distance (in the car body local coordinate system) A from the air intake 412 towards the front of the vehicle 400. The apparatus 414 may be positioned away from the intake for ease of installation (for example packaging, access or wiring location).

The vehicle 400 is backing down a slope 6 (for example a slipway). The angle of the slope 6 shown in figure 7 is exaggerated for clarity.

The vehicle further comprises an angular orientation sensor 450 which detects the tilt angle B of the vehicle. As can be observed in figure 7, because the vehicle 400 is tilted, the water level L at the intake 412 is high, whereas the level measured by the sensing apparatus 414 would be lower (L'). Therefore there is a risk that the driver may travel into unsuitable depths of water.

In order to compensate, the vehicle 400 comprises a memory and processor (not shown) configured to adjust the reading L' to compensate for the angle B. In this instance, the level L can be calculated by L = L' + A.tan(B).

The apparatus 414 may comprise sensor electrodes moulded into the wheel arch trim or similar.

Turning to figure 8, a vehicle 500 is shown driving down an inclined slope 2 whilst wading through water 4. The vehicle comprises a water level sensor 502 (similar to those described above, or ahernatively the sensor could be a hydrostatic pressure sensor or any other sensor capable of measuring water depth) and a vehicle angular orientation sensor 504.

The water level sensor 502 measures a water level L which is combined with an on-board ride height measurement to provide a water depth Dl at the sensor 502. The angular orientation sensor 504 measures an inclination angle C of the vehicle 500.

The vehicle 500 comprises a processor and memory (not shown), the memory having software loaded thereon which is executable by the processor to estimate a depth D2 at a distance X from the front of the vehicle.

The depth D2 is calculated by the relation D2 = Dl + Y.tan C, where Y is the sum of the distance X and the distance from the front of the vehicle to the sensor 502.

The system allows the user to select values of X, and may display values of D2 for multiple values of X. Figure 8 shows the system estimating depth in the direction of travel, but the system can also estimate depth in other directions (e.g. left and right) by using the roll angle of the vehicle as well as the pitch angle.

Variations are possible within the scope of the present invention.

One or both of the electrodes may be a vehicle component. For example, the system may be configured to measure the resistance or the capacitance between two conductive but electrically isolated parts of the vehicle body, such as panels.

The apparatus may be provided as a retrofit system on a replacement vehicle component.

Claims

Ctaims 1. A wading vehicle water level measurement apparatus comprising a vehicle component having a capacitive or resistive water level sensor attached to an exposed surface in use.
2. A wading vehicle water level measurement apparatus according to claim 1 in which the sensor is configured to detect a plurality of water levels.
3. A wading vehicle water level measurement apparatus according to claim 2 in which the sensor is configured to detect changes in the water level continuously.
4. A wading vehicle water level measurement apparatus according to claim 2 in which the sensor is configured to detect changes in the water level in a plurality of discrete levels.
5. A wading vehicle water level measurement apparatus according to any preceding claim in which the sensor comprises a pair of elongate electrodes oriented in a vertical sense with respect to the vehicle local coordinate system such that the water level may be determined by measuring the resistance / capacitance across the sensor electrodes.
6. A wading vehicle water level measurement apparatus according to claim 4 in which the sensor comprises an array of electrode pairs oriented in a vertical sense with respect to the vehicle local coordinate system.
7. A wading vehicle water level measurement apparatus according to claim 4 in which the sensor comprises a single elecfrode on a first side of the sensor and a plurality of electrodes on a second side of the sensor.
8. A wading vehicle water level measurement apparatus according to any preceding claim in which the sensor is positioned below a lowest water-critical component of the vehicle.
9. A wading vehicle water level measurement apparatus according to claim 8 in which the sensor is positioned below the engine air intake.
10. A wading vehicle water level measurement apparatus according to any preceding claim in which the sensor is activated by a wading sensor configured to detect the presence of water adjacent the vehicle.
11. A wading vehicle water level measurement apparatus according to claim 10 in which the wading sensor may is a PDC (parking distance control) sensor configured to detect the presence of water.
12. A vehicle comprising an apparatus according to any preceding claim.
13. A vehicle according to claim 12 comprising: an angular orientation sensor such as an accelerometer or gyroscope and a water level detection control system comprising a memory and a processor, in which the memory is configured to store a water level measurement from the water level sensor and a vehicle orientation from the angular orientation sensor, the memory further storing software executable by the processor to determine a water level on the vehicle at a position spaced from the water level sensor.
14. A vehicle according to claim 12 or 13 in which the sensor is positioned on the front subframe, radiator support pack, bumper beam, wheel arch liner, suspension knuckle or lower arms.15. A vehicle according to any of claims 12 to 14 in which multiple sensors are positioned across more than one component of the vehicle spaced in the longitudinal and / or transverse directions.
15. A vehicle according to any of claims 12 to 14 in which the sensor is provided on a dedicated elongate member extending vertically in the car body local coordinate system.
16. A method of detecting the orientation of a vehicle comprising the steps of: providing a vehicle, providing a plurality of spaced water level sensors, at least partially immersing the vehicle and the sensors in water, measuring the water level at each sensor, calculating the angular orientation of the vehicle from the sensor readings.
17. A vehicle comprising a wading water level sensor, a vehicle angular orientation sensor, a processor and a memory, the memory having a program loaded thereon configured to, when run by the processor, calculate an estimated water level at a predetermined distance from the vehicle using a reading from the wading water level sensor and a reading from the angular orientation sensor.
18. A vehicle according to claim 17 in which the program is configured to calculate the estimated water level at a plurality of distances from the vehicle in the same direction.
19. A vehicle according to claim 17 in which the program is configured to calculate the estimated water level at a plurality of directions from the vehicle.
20. A method of estimating a water level ahead of a wading vehcile comprising the steps of: providing a vehicle having a water level sensing apparatus and an angular orientation sensor, at least partially immersing the vehicle, measuring the water level using the water level sensing apparatus, measuring the vehicle angular orientation using the angular orientation sensor, calculating an estimated water level at a predetermined distance from the vehicle using the water level and the angular orientation.