FIELD OF THE INVENTION

The present invention relates to a novel method and apparatus for monitoring towed vehicles. More particu¬ larly, the method pertains to one or more markers which are mounted on the towed vehicle and one or more monitors which are mounted in alignment on the towing vehicle to thereby enable the relative displacement of each vehicle to be monitored through one or more rear view mirrors.

BACKGROUND OF THE INVENTION

There are many types of towed vehicles, such as trailers and the like, which are not visible in one or more rear view mirrors mounted on the towing vehicle. The problem is particularly acute with wide recreation vehicles or motor homes. Since a narrow vehicle being towed behind a motor home is not visible to the driver of the motor home in the sight lines of any of his side mounted rear view mirrors, or the centre mounted rear view mirror, if appli¬ cable, the driver has no idea whether the vehicle is behaving properly.

There are many things which can go wrong with a towed vehicle. The hitch can fail or come loose. One of the tires can become flat. A wheel bearing can seize. An axle can bend or fail. Some part of the suspension can fail. The towed vehicle can be struck from the rear. Since the motor home or towing vehicle is heavy and has a lot of momentum, it is very difficult for the driver of the towing vehicle to sense through the feel in the steering wheel that something is wrong with the towed vehicle, particularly if it cannot be seen.

In the absence of a timely warning to the driver of the towing vehicle, hitch failure may result in the loss of the towed vehicle or the development of various hazard-

ous conditions. Without the generation of an early warning to the driver when tire, bearing, axle, or suspension problems begin to develop, the driver of the towing vehicle will carry on until a serious problem has occurred such as having the trailer dragged behind the towing vehicle thereby resulting in damage or destruction of the towed vehicle. The heat generated by dragging a trailer over a prolonged distance, with a low or flat tire or with metal in contact with pavement, presents a danger of fire to inflammable components which may then consume the towed vehicle when the towing vehicle is eventually stopped. Minor rear end impact is difficult to detect, yet it can be sufficient to damage a towed vehicle without alerting the driver of the tow vehicle.

When the towed vehicle is or is not visible to the driver of the towing vehicle, it is still a problem with long towed vehicles such as trailers to determine in the rear view mirror the precise position of the rear end of the trailer. When the markers are mounted at the extreme side rear of the towed vehicle, the markers ident¬ ify the rear point, giving the driver increased judgement for safer lane changes, maneuvering through tight spots, parking and backing up. For example, with a boat behind a motor home, it is difficult for the driver to back the boat or boat trailer to the water without jack-knifing. The markers mounted on each side of the boat trailer duplicate the movement or location of the boat and assist in backing up.

The foregoing problems have recently been ad¬ dressed by "high tech" solutions, such as mounting a video camera on the back of the towing vehicle with the camera focused upon the towed vehicle. The video camera solution is expensive and does not provide a complete solution because it does not give an early warning of developing problems. The camera is unavoidably mounted on the top of

the towing vehicle and is focused on the top of the towed vehicle. If the video camera is mounted on either side, it is vulnerable to damage by vandalism or colliding with a stationary object. A problem manifesting itself in a change in the positioning of the towed vehicle must be well advanced in order for the problem to be visible in the video camera from that vantage point.

U.S. Patent No. 4,257,706, Smith, issued March 24, 1981, discloses motor vehicle back-up limit gauging methods and apparatus which include a pair of line-of- sight indicators affixed to the left side of the vehicle.

They are placed in such positions that the driver of the vehicle when seated in the driving position may establish a line-of-sight by aligning these indicators through the existing rear view mirror. He or she may then back the vehicle to a safe distance from a building wall or other marker by halting the backward progress of the vehicle when the aligned indicators coincide with the ground line of the wall, or with the marker. There is no teaching of a marker and monitor system which relates the position or condition of the towing vehicle with the towed vehicle.

The invention disclosed in U.S. Patent No. 2,984,011, Hamilton, issued May 16, 1961, relates to a towed vehicle hitching guide which may be used in conjunc¬ tion with a rear view mirror on the driver's side of the vehicle to enable the driver to properly steer the towing vehicle while backing it up to line up the hitching connec- tion on the towing vehicle with the corresponding connec¬ tion on the towed vehicle. This system does not enable the driver to monitor the position or condition of the trailer.

SUMMARY OF THE INVENTION

The present invention provides a method for monitoring the position or location of towed vehicles, such

as trailers and the like, which are visible or not visible in one or more side mounted rear view mirrors of a towing vehicle. The method comprises, firstly, attaching one or more markers to a towed vehicle such that the marker(s) are visible to the driver on at least one side of the towing vehicle to which the towed vehicle is coupled. The mar¬ ker(s) can have enlarged ends to thereby improve the visibility of the marker(s) in the rear view mirrors of the towing vehicle. Secondly, one or more reference markers are attached to one or both sides of the towing vehicle in a position such that the reference markers are in linear alignment with the marker(s) when viewed from one or more side mounted rear view mirrors of the towing vehicle. When the marker(s) cease to be in linear alignment with the reference marker(s) during driving, the driver of the towing vehicle knows there has been an alteration in the relative position of the towed vehicle and the towing vehicle thereby indicating a potential problem which requires stoppage of the vehicles.

The invention provides a method of monitoring the relative orientation of a towed vehicle coupled to a towing vehicle equipped with one or more side mounted rear view mirrors which comprises: (a) attaching a reference marker to the side of the towed vehicle, the marker being visible in the rear view mirror of the towing vehicle; (b) attach¬ ing a monitor to the side of the towing vehicle in a position that the monitor intersects the line of sight between the marker and the rear view mirror.

In another aspect, the invention includes an apparatus which can be used in accordance with the teach¬ ings of the described method. The marker mounted on the towed vehicle can be a tubular telescopic body having a first end which attaches to the towed vehicle. The first end can be secured to the towed vehicle by a spring to enable the telescopic body to pivot relative to the towed

vehicle. The second end remote from the towed vehicle can be enlarged to enhance visibility. The second end can be coated with a fluorescent or reflective material or can be illuminated.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein:

Figure 1 represents a side elevation of a motor home towing an automobile with the front wheels mounted on a towed trailer.

Figure 2 represents a top view of the two ve¬ hicles illustrated in Figure 1.

Figure 3 represents a driver's view through a rear view mirror side mounted on the motor home.

Figure 4 represents a side elevation of the vehicles illustrated in Figure 1, except that the vehicle being towed has a flat tire.

Figure 5 represents a driver's view through a rear view mirror side mounted on the towing vehicle when the trailer has a flat tire as illustrated in Figure 4.

Figure 6 represents a side elevation of a single axle vehicle being towed by a motor home.

Figure 7 represents a side elevation of the vehicles illustrated in Figure 6, except that the hitch of the vehicle being towed has disconnected.

Figure 8 represents a top view of the two ve¬ hicles illustrated in Figure 7.

Figure 9 represents a side elevation of the same vehicles illustrated in Figure 1, except that the front wheels of the vehicle being towed have moved partially off the trailer.

Figure 10 represents a top view of the two vehicles illustrated in Figure 9.

Figure 11 represents a driver's view through a rear view mirror mounted on the side of the towing vehicle illustrated in Figures 7 or 9.

Figure 12 represents a perspective view of a specific embodiment of a marker mounted on a trailer.

Figure 13 represents a top view of a specific method of illuminating the marker apparatus illustrated in Figure 12 by the tail lights of the towing vehicle for night operation.

Figure 14 represents a detailed view of a tail light adapted to illuminate the marker illustrated in Figure 13.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

Specific embodiments of the method and apparatus of the invention will now be described in detail with reference to Figures 1 through 14. The basic concept of the described method is that a potential problem with a vehicle which is being towed, or the towing vehicle itself, will manifest itself by an alteration in the alignment of one or more markers mounted on the towed vehicle and one or

more reference markers mounted on the towing vehicle. If the towing vehicle develops a problem such as a leaking tire, its position relative to the towed vehicle will become altered. If a problem develops with the towed vehicle, for example, a disconnected hitch, its position relative to the towing vehicle will also become altered. The method of the invention therefore enables the relative positioning of both the towing vehicle and the towed vehicle to be monitored. The method is particularly adapted to monitor towed vehicles, such as trailers and the like, which are not visible in a side mounted rear view mirror of a tow vehicle.

The method of the invention in a specific version comprises the following steps, as illustrated with refer¬ ence to Figures 1 and 2. Firstly, a pair of marker rods 12 is attached to each side of a towed vehicle 14. The rods 12 are preferably attached adjacent each axle 16 of the towed vehicle. In Figures 1 and 2, two rods 12 are used, whereas with the single axis trailer illustrated in Figure 6, only one rod is used. However, only one pair of rods 12 can be used in the embodiment shown in Figures 1 and 2 if desired. The pair of rods 12 are arranged to extend laterally from each side of the towed trailer 14 until they are visible beyond each side 18 of the towing vehicle 20 to which towed vehicle 14 is coupled. The unattached end 22 of each of the rods 12 are enlarged so as to be clearly visible in the side mounted rear view mirrors 26 of the motor home 20. Secondly, a pair of reference markers 24 are attached to each side 18 of the towing vehicle 20 in a position such that each reference marker 24, when seen in the side mounted rear view mirror 26 from the driver's seat, is in linear alignment with the respective enlarged unattached ends 22 of the respective rods 12. The desired linear alignment as viewed by the driver in the rear view mirror 26 is illustrated in Figure 3. As can be seen, the reference marker 24 virtually covers the enlarged end 22.

If the enlarged attached end 22 of either rod 12 ceases to be in linear alignment with the reference marker 24 during highway driving, the misalignment serves as a signai to the driver of the tow vehicle 20 that there has been an alter- ation in the respective positioning of the towed vehicle 14 and the towing vehicle 20 thereby indicating a potential problem which probably requires stoppage of the vehicles 20 and 14.

A typical linear misalignment of the marker 12 and reference marker 24 is illustrated in Figure 4 with respect to a flat tire on the towed vehicle 14. When a flat tire occurs, the towed vehicle 14 becomes lower on that side and the driver of the tow vehicle 20 sees in side mounted rear view mirror 26 the marker-reference marker misalignment as illustrated in Figure 5. The marker 22 has dropped out of alignment with reference marker 24 and the driver then knows that a problem has occurred.

A further example of linear misalignment is illustrated in Figures 7 and 8, where a single axle trailer 14 as illustrated in Figure 6 has developed a disconnection at the hitch. In Figure 6, the reference marker 24 and the marker 22 are in visual alignment when seen from rear view mirror 26. However, when the hitch 25 becomes disconnected as illustrated in Figures 7 and 8, misalignment occurs. This results in towed vehicle 14 not travelling snugly and securely behind tow vehicle 20. The towed vehicle 14 in such a case usually begins to whip or swing back and forth from side to side. In the absence of the apparatus and method of the invention, the lateral movement of towed vehicle 14 would not be visible to the drive of tow vehicle 20 until the trailer "jack-knifed" which is a dangerous condition because the towing vehicle 20 may be thrown out of control. With the apparatus and method of the inven¬ tion, the driver of towing vehicle 20 would see in rear view mirror 26 that the marker 22 was moving from side to

side and was out of alignment with reference marker 24. Such a situation is illustrated in Figure 11.

A further example of misalignment is illustrated in Figures 9 and 10. Towed vehicle 14, as illustrated in Figures 9 and 10, consists of the combination of a car 13 with its front wheels 15 mounted on a single axle trailer 17. In Figures 9 and 10, towed vehicle 14 is illustrated in a condition where one of the tie downs for the front car wheels 15 has come loose thereby permitting one of the wheels 15 of the car to come off the trailer 17. This is a situation which is quite common in the trailer industry. In the absence of the applicant's apparatus and method, the car 13 would be dragged down the highway at an angle thereby wearing away the rubber on the tires of rear wheels 19 of the car 13 and eventually even the metal rims of the rear wheels 19. With the method and apparatus of the invention, the driver of the tow vehicle 20 would see in the side mounted rear view mirror 26 the view that is illustrated in Figure 11, and can be alerted to a problem.

It is to be understood that the method and apparatus of the invention perform properly in alignment when the towing vehicle and the towed vehicle are travel- ling down a horizontal straight road. The markers and the reference markers move out of alignment when curved or hilly grades are encountered. The driver is aware of this and checks the markers and reference markers when travel¬ ling on level straight roads. However, with experience, the driver can learn to use the markers and reference markers even on curves or hills.

Figure 12 illustrates an isometric view of a specific rod-like apparatus 12 for monitoring towed ve- hides.. Rod 12 consists of a plurality of tubular sections

30 which are telescopically connected. The sections 30 may be telescopically extended to lengthen the rod 12 or

telescopically nested to shorten the rod 12, in order to accommodate various widths of towing vehicles 20. Rod 12 has a first end 32 which is secured to the towed vehicle 14 and a bulbous enlarged second end 22, which is readily visible to the driver in the rear view mirror 26. It is advantageous that the bulbous enlarged second end 22 is made of materials which reflect light or are capable of illumination in some way so as to improve visibility. It is also advantageous that the bulbous enlarged second end 22 be adapted to withstand considerable abuse because it will undoubtedly collide at some point with a stationary object. For this reason, the construction materials used must be durable, impervious to the elements, and impact resistant in the event that the bulb 22 is struck against another object. The applicant has found that a fluorescent coloured cylinder with an impact resistant bumper on the end is suitable for the purpose.

When the rod 12 is installed, first end 32 of rod 12 is secured by a spring 34 to the towed vehicle 14. The spring 34 is advantageous because it enables pivoting. Otherwise, the rod 12 will tend to break as a result of excessive vibration on rough roads, or as a result of striking a stationary object. An example where an object may be struck by bulbous unattached end 22 of rod 12 is in turning a tight corner where a power pole is positioned immediately adjacent the corner. Rod 12 must be secured to towed vehicle 14 in such a manner as to permit adjustment on a vertical plane in order to allow bulbous unattached end of marker rod 12 to be placed in linear alignment with monitor projection 24. The specific embodiment illustrated uses a bracket 36 which permits pivotal movement of the rod 12, not only for linear adjustment but also for movement into a stored position when the rods 12 are not required for monitoring purposes.

In a specific embodiment, the marker 22 may be coloured yellow and the reference marker 24 may be coloured red. In this way, the driver can readily identify each component, by using any contrasting colour. If a middle marker is used, it can be coloured amber, for example. In another embodiment, the marker rod may be mounted horizon¬ tally and the reference marker may be mounted vertically. In this way, they act as one quarter of a set of cross hairs. Thus the driver can readily detect when there has been a change in the angle between the marker rod and the reference marker.

The use of the apparatus illustrated has been described in relation to the method of the invention. Rods 12 are pivoted from a stored position to an operative position. The operative position is when the enlarged bulbous ends 22 of rods 12 are extended telescopically until they are visible beyond each side 18 of a tow vehicle 20. The spring 34 provides the resiliency required so that when objects are struck during use, the rods 12 do not become bent or break off.

In order to use the specifically described method and apparatus at night, the enlarged ends 22 of the rods 12 must be visible to the driver of the tow vehicle 20 in his side mounted rear view mirror 26. Light bulbs can be installed in the enlarged ends 22. However, this is relatively expensive. Further, the light bulb, and even the wiring to the light bulb can break due to any impact that the rods 12 receive when they strike stationary objects. An alternative, less expensive and more trouble- free method of illumination has been invented as illus¬ trated in Figure 14. The method involves drilling a hole 41 through each of the rear tail lights 40 of the two vehicles 20 and 14. An optic fibre 42 or a group of fibres is then inserted into each of the holes 41. The optic fibre 42 would normally be sealed in position by a clear

sealant 43 to keep water and dirt out of the rear tail light. The optic fibre 42 in each rear light is aligned with the respective enlarged ends 22 of the applicable rods 12 on the respective sides of the vehicle. Light from each light bulb 46 within each rear tail light 40 then shines through respective optic fibre 42 and produces a beam of light 44 which is focused upon the enlarged end 22 of the rod 12 that is located rearwardly of that light. This makes the end 22 visible to the driver for night driving. In appropriate cases where two sets of rods 12 are used on each side, a similar procedure would be followed by insert¬ ing an optic fibre 50 into tail lights 48 of towed vehicle 14 to project beams of light 52 upon the bulbous enlarged ends 22 of the rearwardly positioned rods 12. The fluor- escent material on the ends 22 readily reflects the beamed light and is easily seen in the rear view mirror 26. In certain cases, it may be advantageous to illuminate the monitors. However, generally, the monitor does not have to be illuminated because it is used only to obscure the marker. If the illuminated marker becomes visible to the driver, then it has moved out from behind the monitor and the driver knows then that there has been a change in position.

The method as described provides a simple and inexpensive method of monitoring towed vehicles, such as trailers and the like, which are, or are not, visible in a side mounted rear view mirror of a tow vehicle. The apparatus, as described, provides an effective device for use in accordance with the teachings of the method. It will finally be apparent to one skilled in the art that modifications may be made to the specific embodiments of the apparatus. In particular, enlarged unattached end 22 of rods 12 need not be bulbous, as a different geometric figure can be used. Also, various ways of illuminating the markers can be used.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.