The present invention claims priority from Australian provisional patent application no. 2017903870, filed 22 September 2017, the entire contents of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates generally to towed vehicles, such as trailers and recreational vehicles such as caravans, camper trailers and the like. In particular, the present invention relates generally to a system and method for measuring and managing the weight of the towed vehicle that takes in to consideration the effects of movement on loads and load distribution.

BACKGROUND OF THE INVENTION

Recreational vehicles, such as caravans and camper trailers, are a popular form of portable accommodation used by many as an economic and enjoyable way in which to experience the outdoors in an independent and comfortable manner. They are typically hitched behind a passenger vehicle and towed to a destination where they are unhitched from the towing vehicle and set up as an accommodation site in accordance with the user's personal preferences.

With a caravan in particular, prior to leaving on a caravan trip, it is common for the caravan owner to pack the caravan with equipment to be used whilst on holiday. As a result of this, in many instances the weight of the caravan can be considerable at the start of a journey due to the combined weight of the body of the caravan and fltout, as well as the stowed equipment.

Controlling and understanding the mass of a towed vehicle is critical to safe towing. Each trailer and recreational vehicle (RV) is provided with a weight compliance specification that determines a safe weight range for towing. There are various types of weights to consider when towing a recreational vehicle. These include the Tare Mass (TM), Gross Trailer Mass (GTM), Aggregate Trailer Mass (ATM), Payload and Ball Weight. The TM is the mass of the trailer/RV with no payload and is generally specified on the vehicle identification plate. The GTM is the maximum possible weight that can be supported over the trailer's axle, which includes the maximum allowable payload but not the Ball Weight. The GTM is also typically listed on the vehicle identification plate. The ATM is the tare mass of the trailer plus the payload, which is the maximum the trailer/RV is able to weigh in transit. The Payload weight includes everything that is added to the towing vehicle, including any extra fuel/water as well as any accessories. The Ball weight is the weight incident on the tow ball of the towing vehicle and generally equates to the ATM - GTM.

Poor weight distribution can cause significant safety issues when towing a trailer/RV. If the ball weight is too heavy, it can lift the front end of the towing vehicle and reduce the ability of the vehicle to safely brake and steer. If the ball weight is too light, trailer/RV sway is likely to result. These issues can be addressed by redistributing the payload across the vehicle so that the main weight of the towed vehicle is over the vehicles axles.

There exist weighbridges and other static weighing means for measuring these weights. However, these means do not take into consideration environmental loadings and other events that can occur during motion when weights can shift, thereby having an adverse weight on the tow ball. Similarly, whilst correct weight distribution may have been established prior to commencement of a journey, during the journey the trailer/RV may have hit a pothole or other rough terrain causing the weight distribution to change and bringing the towing situation into danger.

Thus, there is a need to provide a simple and effective means for measuring weight distribution in a trailer or towed recreational vehicle that can provide direct feedback to the user of any weight distribution problems both prior to, and during, a journey.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the present invention there is provided a weight management system for towing a vehicle comprising; a plurality of weight sensors for determining weight of the towed vehicle passing through one or more axles of the towed vehicle;

a bending moment sensor for measuring a bending moment present on a portion of the chassis of the towed vehicle;

a computer processor for receiving data from each of the weight sensors and bending moment sensor and for processing said data to detect a condition whereby a weight of the towed vehicle falls outside of a predetermined weight condition and/or a bending moment present on the chassis exceeds a bending moment limit;

wherein, the computer processor is configured to transmit a warning signal to a driver of the towed vehicle when one or more of said conditions is detected.

In an embodiment, the plurality of weight sensors comprise a compression sensor mounted between the chassis of the towed vehicle and a spring of the suspension of the towed vehicle.

The computer processor may be provided with data supplied by the manufacturer of the towed vehicle setting the Tare Weight, Gross Trailer Weight and Aggregate trailer mass of the towed vehicle, prior to operation.

The bending moment sensor may be mounted to an arm of the towed vehicle connecting the towed vehicle to a hitching mechanism for hitching to the towing vehicle. In one form, the bending moment sensor may be mounted within said arm and may comprise a capacitive sensor for determining deflection of the arm in the presence of said bending moment. In another form, the bending moment sensor may be mounted within said arm and may comprises an optical sensor for determining deflection of the arm in the presence of said bending moment

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Fig. 1 is a side view of caravan suitable for use with the present invention;

Fig. 2 is an isolated view of a suspension mounted compression sensor for use with the present invention in accordance with an embodiment.

Fig. 3 is a top view of a front end of the caravan and the manner in which bending moment sensors may be fitted to the arms of the caravan in accordance with an embodiment of the present invention;

Fig. 4 is a side view showing an alternative embodiment for fitting a bending moment sensor in accordance with the present invention;

Figs. 5A and 5B show relaxed and stressed depictions of the bending moment sensors of an alternative embodiment in action;

Figs. 6A and 6B show relaxed and stressed depictions of the bending moment sensors of yet another alternative embodiment in action;

Figs. 7A - 7C show message samples for delivery by the computer of the present invention to a driver of the towing vehicle in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention will be described below in relation to a caravan of the type that is to be towed by a vehicle. However, it will be appreciated that the present invention could be equally employed in any variety of recreational vehicles and camper trailers that are to be towed by a vehicle and still fall within the spirit of the present invention.

Referring to Fig. 1, a caravan 10 is depicted for application of the present invention in accordance with an embodiment thereof. The caravan 10 is of a conventional type and comprises a chassis 14 that supports a body 12. The body 12 forms an enclosure over the top of the chassis 14 and is configured to function as a mobile accommodation space, as is well known in the art. A hitch 15 is attached to a front end of the chassis 14. The hitch 15 attaches to a tow ball or the like of a towing vehicle (not shown) and may be configured in a variety of different ways so as to provide secure attachment to the towing vehicle as well as the transfer of control signals from the towing vehicle to the caravan 10 so as to operate the turning signals of the caravan 10 and various other functions as would be well understood by those skilled in the art.

The chassis is supported above a ground surface by way of a pair of wheels 16 mounted upon a pair of axles 17 that extend across the chassis 14. Each of the wheels 16 are mounted on opposing ends of the axles 17 with the axles 17 centrally located with respect to the caravan 10. Each of the wheels 16 are free to rotate on the axle under the towing force supplied by the towing vehicle. Whilst two sets of wheels 16 on a pair of axles 17 are depicted in the embodiment of Fig. 1, it will be appreciated that in some situations, only a single set of wheels 16 on a single axle 17 may be employed.

With reference to the caravan of Fig. 1, three weights A, B and C are depicted. Weight A is representative of the pay load weight of the caravan 10, namely everything added to the caravan, such as non-standard accessories, extra fuel/water, luggage, bedding and the like that does not form part of the standard Tare weight as specified on the vehicle identification plate. Weight B is the weight of the vehicle that is supported over the caravan's axles 17. Weight C is the Tow Ball weight, namely the download weight present on the tow ball of the towing vehicle. The caravan 10 may be fitted with an angular sensor, typically an accelerometer or the like, that is capable of measuring the angular position of the caravan 10 in relation to a flat surface. This enables the system to operate even when the caravan 10 is located on an uneven surface, such as when parked on an incline on a driveway or the like. By constantly identifying the angular position of the caravan by the accelerometer, it is possible to normalize the weight of the caravan to obtain true C and B weights. As it is well established that the ball weight of a caravan is much higher if parked downhill due to the hitch 15 pushing down upon the tow ball, the provision of an accelerometer on the caravan overcomes this problem.

By directly measuring weight B in accordance with the present invention, and having a knowledge of the payload weight A added to the caravan, it is possible to establish a variety of additional measurements. In essence, it is established that:

Gross Trailer Mass (GTM) = A + B

Aggregate Trailer Mass (ATM) = A + B + C

Tare Mass = B + C

C = ATM - GTM

It will be appreciated that the caravan identification plate will list the Tare Mass and the ATM and GTM.

In accordance with an embodiment of the present invention, in order to constantly monitor the weight B present on the axles 17 of the caravan 10 a compression sensor 20 is fitted between the spring member 22 of the suspension system 16 of the caravan, and the chassis 14, as depicted in Fig. 2.

It will be appreciated that the weight of the combined weight of the caravan will pass through the axles 17 and by placing a conventional compression sensor 20 at this location, the weight is able to be measured and monitored prior to journey, as well as during journey to ensure that the limits as set by the manufacturer of the caravan are maintained within safe limits. An angular sensor 20a is also mounted in the suspension system 16 as the calculated force is a ration of the angle via the fixed pivot arm to the spring. This can then be used to determine the vertical weight B acting on the axles 17 of the caravan.

It will be appreciated that the compression sensor 20 may be a conventional axel type sensor that employs a conventional Wheatstone bridge arrangement to sense weight load. The sensors 20 and 20a may be equipped with a transmitter to transmit readings in real time to a computer (not shown) amounted within the caravan 10. The computer may also receive an estimate of the payload weight A, provided by the user prior to journey as a combined weight of the non-standard features being carried by the caravan 10. As the computer is provided with the Tare weight of the caravan from the manufacturer specifications, the Ball weight, GTM and ATM are able to be readily calculated each time the computer receives a different sensed Weight B to ensure that the various weight guides are retained within the predetermined specified safe ranges.

If the computer calculates one or more of the Ball weight, ATM or GTM being outside a specified range, the computer will send an alert to the driver through the caravan electronic connection, indicating to the driver that the weight distribution of the caravan has brought one or more of the established measurements outside the established safe range. The driver will then be able to stop the vehicle and redistribute the weight to address any such problems.

As is depicted in the embodiment of Fig. 3, the present invention is also capable of monitoring other stresses on the towing vehicle and providing the driver with an indication that these stresses are at a level that requires re-distribution of the towing weight, despite the other weight measurements being within pre-defined limits. Typically, in towing situations, the towing weight may be located toward the rear of the caravan, towards the front of the caravan or towards one side of the caravan, resulting in a significant reduction of handling control. As a result of this weight distribution problem, the forces applied by such weight onto the front end of the vehicle chassis can cause bending moments in the chassis forward of the wheels, namely the triangularly extending arms 30, 32 of the frame extending from the hitch 15, as shown in Fig. 3.

It will be appreciated that depending on the direction of motion and the inequality of weight distribution in the caravan, the bending moments present on the arms 30, 32 may be in an upward or downward direction or laterally. Thus, by measuring the amount of flex or distortion of these arms 30, 32 during towing, such forces can be monitored and conveyed to the driver of the towing vehicle.

A preferred means for doing this is by causing a disconnection in the arms 30,32 and placing a tension/compression sensor arrangement 100 within the disconnection such that all forces acting on the arms 30, 32 pass through the tension/compression sensor 100 as shown. Tests can then be conducted to determine what types of readings are indicative of an unsafe load condition such that these measurements can be monitored during towing and if determined to exceed a predetermined setting, a warning signal will be sent to the driver instructing the driver to either stop of the forces exceed safe levels, or to exercise care if the forces are approaching an unsafe level.

Referring to Fig. 4, another embodiment depicting how this may be achieved is shown. In this embodiment a compression sensor 35 is applied to an underside of one of the arms 30 or 32. The compression sensor 35 may be a conventional compression/tension sensor in the form of a strain gauge using a compression/tension Wheatstone bridge. Any strain bending moment present in the arm 30 or 32 will generate an output voltage which can be sensed and processed by the computer present in the caravan. The computer can then determine the amount of strain or stress being placed on the arms 30, 32 of the caravan and warn the driver if the sensed forces are above a threshold force.

In an alternative embodiment as is shown in Fig. 5A and 5B, the amount of deflection of the arms 30, 32 due to bending moments brought upon by poor weight distribution may be measured by a capacitive sensor system. In this embodiment, a conductive rod 38 may be mounted to extend within the hollow arms 30, 32 as shown. At a distal end of the arm 30, 32 a conductive plate 40 is fitted to measure the capacitance between the free end of the rod 38 and the surface of the plate 40. In an unloaded state, as depicted in Fig. 5A, the distance 'x' between the end of the rod 28 and the plate 40, is a substantially constant, resulting in a substantially constant capacitance sensed between the end of the rod 38 and the plate 40. If, as is depicted in Fig. 5B, the forces present upon the arms 30, 32 change, as may be the case in a shift in the weight distribution in the caravan, the arm 30, 32 may flex in the manner as shown, shortening the length of arm 30, 32. The rod 38, which is only fixed at one end, will not experience the same bending force and will retail its length thereby bringing its end closer to plate 40 and reducing the distance 'x'. This will be detected as an increase in capacitance and this value can then be used by the computer present in the caravan to generate a message to the driver if the detected capacitance level exceeds a predetermined amount indicative of a dangerous driving situation.

An alternative embodiment for determining the magnitude of a bending moment acting on the arms 30, 32 of the caravan is depicted in Fig. 6A and 6B. This embodiment functions on substantially the same principal but rather than employing capacitance as the means for detecting movement, the embodiment employs an optical sensor.

As shown in Fig. 6A, in an unloaded state, the light emitter 50 is mounted within the arm 30, 32 and emits light that is incident on an optical sensor plate 52 located at an opposing end of the arm 30, 32. The emitted light will be incident upon a substantially central location of the optical sensor plate 52 when the bending moment experienced by the arm 30, 32 is negligible. As the bending moment increases, typically due to a shift in the weight distribution in the caravan, the arm 30, 32 will flex in the manner as shown, thus moving the optical sensor plate 52. As a result, the light emitted by the light emitter 50 will move towards an edge of the optical sensor plate 52 and the distance moved will be detected and transmitted to the computer carried by the caravan for processing. If the computer determines that the change in incident light is significant, an alarm will be sent to the driver of the vehicle warning them that there has been a shift in weight distribution that places the towing situation in a more danger.

It will be appreciated that the computer present in the caravan may transmit information about the weight distribution of the caravan and any changes in distribution to a linked personal computer device, such as a smart phone, rather than directly to the towing vehicle. In this regard, the computer may communicate with a software program carried by a smart phone in the manner as depicted in Figs. 7A - 7C.

In Fig. 7 A, the computer is able to display to the user simple data about the load being towed by the vehicle, such as the trailer weight and the tongue or ball weight and load being carried by the caravan. This information can provide the user, typically the driver, the assurance that the loads are within specified limits.

If there are problems, either prior to the journey or during the journey, the computer can convey those problems in the manner as depicted in Fig. 7B via the user's smart phone or connected electronic interface. If the sensors determine that the weight of the system falls outside recommended guidelines as provided by the manufacturer or governing bodies, this is conveyed by highlighting a specific condition, such as UNSAFE TO TOW, TRAILER WEIGHT EXCEEDS LIMITS. If the bending moments sensors determine an unsafe condition, this can be conveyed by indicating the source of the bending moment, such as LOAD IS TOP HEAVY, to assist the user in correcting or reviewing the problem.

During the towing event, the computer is able to continue reviewing the data being collected and if the data suggested that the weight distribution of the towed vehicle has changed warning signals such as those shown in Fig. 7C may be highlighted. These include, LOAD SHIFT DETECTED, SWAY DETECTED SLOW DOWN as well as SAFE TO TOW.

It will be appreciated that the computer present in the caravan may record the data where it can be used for a variety of purposes to improve knowledge about towing and road safety. This could include providing caravan manufacturers feedback as to the manner in which loads may shift during transit as well as other information about the loading of the caravan; providing insurance companies with information about load conditions in the event of an insurance claim, as well as providing data to governing bodies to provide them with more of an insight into the towing habits of road users for developing legislation and road laws.

It will be appreciated that the system and method of the present invention provides a simple and effective means for capturing data associated with towing a caravan or trailer and ensuring that the weight and weight distribution of the towing situation is managed appropriately. This can be achieved both prior to and during transit so as to cater for weight load shifts and changes in road conditions, which may have an adverse effect on safety.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.