WO2010136960A2

WO2010136960A2 - Traction enhancement system

Info

Publication number: WO2010136960A2
Application number: PCT/IB2010/052302
Authority: WO
Inventors: Charles Lovell Freeman; Francesco Petruccione; John Lovell Freeman
Original assignee: University Of Kwazulu-Natal
Priority date: 2009-05-26
Filing date: 2010-05-25
Publication date: 2010-12-02
Also published as: WO2010136960A3

Abstract

A traction enhancement system suitable for use as part of an integrated braking system of a means of transportation having wheels that engage a surface; the system includes a delivery system suitable for delivering a traction enhancement compound onto a target surface where increased traction is required, and a control system adapted to determine if a collision between the means of transportation and an external object is probable, and to cause the delivery system to be actuated, in order for the delivery system to deliver the traction enhancement compound onto the target surface.

Description

TRACTION ENHANCEMENT SYSTEM

BACKGROUND TO THE INVENTION

THIS invention relates to a traction enhancement system and more particularly but not exclusively, to a traction enhancement system suitable for use as part of an integrated braking system of a means of transportation having wheels that engage a surface. The invention also relates to various sub-systems constituting the traction enhancement system, and to a control system for use in the traction enhancement system.

Many vehicle accidents are caused by unexpected loss of traction. This generally happens when wheels lock during excessive braking. The incidence of loss of traction is furthermore exacerbated by low traction conditions, for example wet weather conditions, or by using worn tires.

ABS (Anti-lock Braking System) has been developed to improve braking by preventing lock up of wheels, and subsequent traction loss. Typically, the coefficient of static friction between two surfaces is greater than that of dynamic friction, therefore skidding or locking of wheels presents a lower frictional force of the contact surface of the wheels on the road. The two advantages of ABS are firstly that it allows the driver to remain in control of the vehicle during braking, as the vehicle follows a predictable path guided by the normal wheel rotation, and secondly it in general will shorten the braking distance in emergency, by means of the friction coefficients explained above. It is recognized that ABS is a very important safety feature, but it will be appreciated that situations may occur where ABS will not be able to prevent an accident from happening due to the effective braking distance not necessarily being reduced sufficiently by ABS. Another way to enhance traction, and thus also to prevent traction loss, is to provide an additional adhesive force between the wheels of the means of transportation and the road surface. This is for instance the case in certain motor sport events, where a traction enhancement composition is applied on the road surface to improve traction. In one example, a compound such as VHT Trackbite ® is applied at a starting point of roads at drag races, in order to improve the grip of the tires when the vehicle is exerting maximum torque. This product can be used on wet or dry surfaces, is biodegradable, not harmful to the environment and relatively inexpensive. However, the use of this or a similar product on an extended length of road surface will not be practically or commercially viable. Even if this is in fact viable, it is in any event foreseen that users will get used to the improved traction, and that shorter following distances will eventually be maintained, thus negating the original advantage.

VHT Trackbite® is a commercially available traction enhancement substance, and comprises a viscous active ingredient mixed with a solvent to decrease the viscosity of the active ingredient. However, in this combination the mixture does not have substantial adhesive properties, and the solvent therefore has to be allowed to evaporate before the applied compound will be effective. In this specification the term "traction enhancement substance" shall be interpreted to include the active ingredients of, but not be limited to, Trackbite® and other similar substances, and mixtures of these active ingredients and other solvents.

It is accordingly an object of the invention to provide a traction enhancement system that will, at least partially, alleviate the above disadvantages.

It is also an object of the invention to provide a traction enhancement system that will be a useful alternative and/or addition to existing braking enhancement systems. It is a still further object of the invention to provide a traction enhancement system that is integrated into a standard motor vehicle or truck or transport device comprising of wheels meeting with a road surface.

SUMMARY OF THE INVENTION

According to the invention there is provided a traction enhancement system, suitable for use with a means of transportation in order to improve traction between a tire of the means of transportation and a surface on which the means of transportation is used, the traction enhancement system including: a delivery system suitable for delivering a traction enhancement compound onto a target surface where increased traction is required; and a control system adapted to determine if a collision between the means of transportation and an external object is probable, and to cause the delivery system to be actuated, in order for the delivery system to deliver the traction enhancement compound onto the target surface.

There is provided for the target surface to be a surface of the tires that engages the road surface, the surface of the road, or both the surface of the tires that engages the road surface and the surface of the road.

There is provided for the delivery system to include a reservoir for in use containing the traction enhancement compound, and an ejector adapted to deliver the traction enhancement compound onto the target surface.

The ejector may be in the form of a nozzle having a first end being in flow communication with the reservoir, and a second end being positioned proximate the target surface, and through which the traction enhancement compound can be expelled onto the target surface.

According to a first embodiment of the invention, the reservoir may include a receptacle having an inlet for receiving the traction enhancement compound, and an outlet being in flow communication with the nozzle.

A flow control valve may be provided between the outlet and the nozzle, and is preferably in the form of a solenoid valve.

The reservoir also includes a heat transfer arrangement for effecting heat transfer between the traction enhancement compound in the receptacle and a heat transfer medium.

The heat transfer arrangement may comprise heat transfer passages for receiving the heat transfer medium, an inlet for receiving the heat transfer medium, and an outlet for discharging the heat transfer medium.

Preferably the heat transfer medium is in the form of water used in an engine arrangement of the means of transport. More preferably, the inlet of the heat transfer arrangement is in flow communication with water from an inlet of a radiator of the engine arrangement, and the outlet of the heat transfer arrangement is in flow communication with an outlet of the radiator.

The heat transfer arrangement may furthermore include a flow control valve for controlling flow of the heat transfer medium through the heat transfer passages.

The flow control valve may be in the form of a thermostatically controlled valve, and may alternatively be in the form of an electronically controlled valve.

The reservoir may also include a pressure sensor and a temperature sensor. There is provided for a delivery system to be located proximate the front wheels, alternatively proximate all wheels, of the means of transportation.

All the delivery systems are in communication with the control system.

The control system of the traction enhancement system may include proximity sensing means for sensing the distance between the vehicle and another external object.

The control system is preferably in communication with an ABS system forming part of the means of transportation.

The control system preferably uses signals from the ABS system and the sensing means as input, calculates whether traction enhancement deployment conditions exist, and sends an actuating signal to the solenoid valve if such condition indeed exists.

There is also provided for the control system to calculate the relative displacement, relative speed and relative acceleration between the vehicle and the external object.

There is still further provided for the control system to receive a signal from a brake light system as claimed in the applicant's co-pending application, South African provisional patent application No 2010/02253, the contents of which is incorporated herein by reference.

According to a second embodiment of the invention, the reservoir may include a receptacle defining an enclosed volume in which the traction enhancement compound may be contained, an outlet being in flow communication with the nozzle, and an inlet being in flow communication with an actuator. There is further provided for the actuator to be in the form of a pressure source adapted to increase the pressure in the reservoir when actuated, so as to force the traction enhancement compound from the reservoir to the nozzle.

The actuator may include a casing for receiving a pressurized cylinder, and a puncturing device suitable for forming an opening in the pressurized cylinder when the actuator is actuated.

Preferably the puncturing device is in the form of a plunger being displaceable between a loaded position wherein the plunger is spaced apart from the cylinder, and a released position wherein the plunger abuts the cylinder, the plunger being biased towards the released position, and being retainable against the bias in a loaded position by a displaceable retaining pin.

The plunger may be biased towards the released position by way of a biasing means, preferably in the form of a helical spring.

The plunger may include a perforating protrusion protruding therefrom, which is adapted to perforate a wall of the cylinder when the plunger is displaced from the loaded position to the released position.

The displaceable retaining pin may be displaceable between an engaged position, in which the retaining pin retains the plunger against its bias in the loaded position, and a disengaged position, in which the retaining pin disengages the plunger so as to allow the plunger to be displaced to the released position.

In a preferred embodiment the retaining pin is displaced between the engaged and disengaged positions by way of a solenoid valve. BRIEF DESCRIPTION OF THE DRAWINGS

Two embodiments of the invention are described by way of non-limiting examples, and with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of the various subsystems forming the traction enhancement system according to one embodiment of the invention;

Figure 2 is a perspective view of a traction enhancement system of Figure 1 located in position relative to the wheels of a motor vehicle, as seen from the front of the vehicle, but without showing the remainder of the standard motor vehicle components that are not of particular relevance insofar as the description of the invention is concerned;

Figure 3 is the perspective view of Figure 2 seen from the rear of the vehicle;

Figure 4 is a perspective view of one embodiment of a pneumatic actuator used in the traction enhancement system of figures 1 to 3;

Figure 5 is a schematic representation of a traction enhancement system in accordance with another embodiment of the invention; and

Figure 6 shows one envisaged control algorithm that may be utilized by the control system of the traction enhancement system. DETAILED DESCRIPTION OF INVENTION

Referring to the figure 1 to 4, in which like numerals indicate like features, a non-limiting example of one embodiment of a traction enhancement system in accordance with the invention is generally indicated by reference numeral 10.

In order to differentiate the various systems making up the traction enhancement system in accordance with the first embodiment, reference is now made to the schematic breakdown shown in figure 1. The traction enhancement system 10 comprises a delivery system 20, for delivering a traction enhancement compound onto a target surface, and a control system 30, which determines when the delivery system 20 should be actuated, and upon determination of such condition sends an actuation signal to the delivery system. The delivery system 20 in turn includes an ejection subsystem 50, which stores, conveys and ejects the traction enhancement compound onto the target surface, and an actuator 40, which receives the actuating signal from the control system 30 and subsequently causes the traction enhancement compound to be pneumatically forced from the reservoir 60, through the nozzle 70 and onto the target surface. These systems and components are now described in more detail below.

The traction enhancement system 10 is, in use, mounted on a vehicle as shown in figures 2 and 3. It will however be appreciated that the configuration shown in the figures is not at all limiting, as various configurations can be utilized, provided that an end of the nozzle 70, or whatever ejection means is utilized, is located proximate, or at least aimed towards a target surface. The target surface may be the tread 1 1.1 of the tires 11 of the vehicle, a part of the road surface 12 ahead of the vehicle, or both the aforesaid. The aim of the invention is to provide a mechanism whereby a traction enhancement compound can be applied to the target surface upon receiving an appropriate signal from the control system. The traction enhancement compound (not shown) is housed inside a reservoir 60 which is located at a suitable beatable on the vehicle. The reservoir 60 has an outlet 62 which is in flow communication with an inlet of a nozzle arrangement 70, and an inlet 61 which is in flow communication with an outlet 48 of the actuator 40. The design of the nozzle arrangement 70 will be dependent on the type of traction enhancement compound used (e.g. liquid, gel, capsule), but will receive the traction enhancement compound to be expelled therefrom from the reservoir. The nozzle 70 will typically have suitable openings in the vicinity of the target surface as defined above.

It should be noted that, in this embodiment, a simple storage reservoir, as shown in the drawings, may not be suitable as the traction enhancing substance may have a very high viscosity. When presented with a force from a pressurized gas, instead of pumping the traction enhancing substance out of the reservoir, it may lead to tunneling, where the easiest route of escape of the gas forms a tunnel through the liquid. This will result in very little of the traction enhancing substance being pumped out, while the forcing mechanism is lost (escaping gas). An alternative approach would therefore be to seal the traction enhancing compound in a thin flexible plastic enclosure that fits into two reservoirs just above each wheel, and then to place a piston-type disc on the top of the bag such that the majority of the gas exerts its force equally across the piston. This will prevent the tunneling effect and allows the plastic bag to be ruptured. The escape orifice at the bottom of the reservoirs will allow the traction enhancing substance to escape onto the target surface, while leaving the flexible plastic enclosures inside the reservoirs (and not polluting the environment or getting stuck on the tires). An additional advantage is that the reservoirs will require minimal cleaning to replace the traction enhancing substance, as the bags may be pulled out and replaced. This is however only one of many embodiments that are foreseen.

The actuator 40 is in the form of a pressurized source that will, when actuated, increase the pressure in the reservoir 60 so as to force the traction enhancement compound from the reservoir 60 into the nozzle 70, from outlet 75, and onto the target surface. More particularly, the actuator 40 includes a casing 41 adapted to receive a pressurized cylinder 42 therein. The cylinder 42 is preferably in the form of a CO₂ cylinder, and is replaceable in that the casing 41 includes a removable end cap 43 that can be removed so as to provide access to the cylinder 42 and the receptacle in which it is located.

A puncturing device in the form of a displaceable plunger 44 is located in an opposite part of the casing 41 , and is displaceable between a loaded position in which the plunger 44 is spaced apart from the cylinder 42, and a released position in which the plunger 44 abuts the cylinder. The plunger 44 is biased towards the released position by way of a helical spring 49. A perforating protrusion 46 protrudes from the plunger 44, and is adapted to perforate a wall of the cylinder 42 when the plunger 44 is displaced from the loaded position to the released position under influence of the spring 49.

Prior to actuation of the actuator 40, the plunger is retained in the loaded position by way of a displaceable retaining pin 45 that engages a circumferential groove 44.1 in the plunger 44 when the retaining pin is in an engaged position (shown in Figure 4). When the retaining pin 45 is displaced to a disengaged position, the plunger 44 is released, and is allowed to be displaced under the influence of the biasing means towards the cylinder, so as to allow the perforating protrusion to puncture the cylinder 42, which in turn allows the high-pressure gas to flow through a port 47 in the plunger 44 towards an outlet 48 of the actuator 40, which is in turn in flow communication with the reservoir in order to pressurize the same as described above.

In the described embodiment the retaining pin 45 is displaced between the engaged and disengaged positions by way of a solenoid arrangement (not shown). The solenoid arrangement is energized by the control system 30, and the working thereof is well known in the art. A second embodiment of the invention is now described with reference to Figure 5. In this embodiment the traction enhancement system 100 comprises a delivery system 200, but no external pressure actuator (40 in Figures 1 to 4) is required due to a different mode of operation, as is discussed in more detail below.

The delivery system 200 includes a reservoir 210 defining a receptacle 213 for receiving and holding the traction enhancement compound, the reservoir 210 having an inlet 211 for receiving the compound, and an outlet

212 which is in flow communication with a nozzle 230. The reservoir 210 furthermore includes a heat transfer arrangement 220 for enabling heat transfer between the traction enhancement compound inside the receptacle

213 and a heat transfer medium. The heat transfer arrangement 220 includes an inlet 221 which is in flow communication with a heat transfer medium source, which in this particular example is a point prior to the inlet of a radiator of the vehicle, and an outlet 223 for conveying the heat^' transfer medium away from the reservoir 210. Heat transfer passages (only schematically indicated by reference numeral 222) extend between the inlet and outlet, and is in heat transfer communication with the receptacle 213. A control valve 225 is furthermore provided on the inlet (alternatively outlet) side of the heat transfer arrangement 220, and enables the control of flow through the heat transfer passages 222. The control valve 225 may be a thermostatically controlled valve (such as for example a wax based valve), but there is also provided for the control valve to be a electronically regulated solenoid valve.

A pressure sensor (not shown) is fitted to the reservoir to detect if leakage of the traction enhancement compound has taken place. A signal from the pressure sensor is fed back to the control system 300. A temperature sensor (not shown) is also fitted in the reservoir to detect if the temperature of the traction enhancement compound is at a value that would be unsafe to use. For example, if the thermostatic valve failed and the temperature were to increase, it would cause an unsafe build-up of pressure of pressure inside reservoir.

A discharge control valve 240 is provided between the outlet 212 of the reservoir and the nozzle 230, and is actuated by a signal received from the control system 300. The control valve 240 is typically in the form of an electronic solenoid valve.

In the embodiment described with reference to figure 5, it is required for the traction enhancement compound to have a low viscosity whilst in the reservoir, and also while being ejected in order for the compound to be sprayed onto the target surface. In order to achieve this, the traction enhancement compound is dissolved in a solvent having a boiling point well below ambient temperatures, and also a low heat of evaporation. In turn, the solution will then be under pressure at room temperature, and will be discharged from the reservoir without the need of an additional pressure actuator as described in the embodiments of Figures 1 to 4. When released to atmospheric conditions, the solvent will evaporate rapidly, leaving only the active ingredients of the traction enhancing compound behind on the tires. Initial investigation has shown that various small molecule refrigerants will be suitable for use as a solvent. It is believed that optimal solvents would be small molecule refrigerants having a low heat of evaporation, and having vapour pressures not exceeding 3000 kPa at 45⁰C. This enables lower cost solenoid discharge valves to be used. The mixture temperature is regulated by way of the heat transfer arrangement so as to provide a constant pressure that will result in predictable nozzle performance, whilst also allowing the system to be used in various ambient conditions.

In the embodiment of Figure 5 the traction enhancement system 100 will include a delivery system 200 located proximate each wheel where additional traction is required. This will typically be the front wheels, but there is also provided for delivery systems 200 to be provided at all the wheels of the vehicle. All delivery systems 200 are however controlled by the same control system 300. A reservoir 210 of a delivery system 200 will typically be located in, or recessed into, the wheel arches above the wheel. There is, however, also provided for the reservoir to be located radially further away from the front of the vehicle to ensure that the time between the traction enhancement compound coming into contact with the tire surface, and for such part of the tire engaging the road, is kept to a maximum to allow for sufficient solvent evaporation.

The control system (30 or 300) determines when the actuator should be actuated by energizing the solenoid arrangement. It should however be noted that the control system will be initiated, and will only remain active, while the ABS system is triggered. The fact that the ABS has been triggered tells the control system that the driver has fully engaged the brake, and that the vehicle is required to stop as soon as possible. It also indicates that maximum traction between the tires and the road has been reached. Without the use of this initiating condition, the control system may cause erroneous deployment of the traction enhancing compound.

The control system may be configured in various ways, but the salient aspect thereof is that it determines when a collision will occur, and upon determining such condition triggers the actuator 40 or the discharge valve 240. The control system typically receives input signals from proximity sensing means 35 that are located on the vehicle, and which measures the proximity of external objects in front of the vehicle to the vehicle while the control system is active. This measurement of the distance to an object at various times can be differentiated to provide velocity and acceleration, which is then used to calculate whether a collision is imminent. In a preferred embodiment, the control system also receives an input signal from the vehicle's ABS, and the control algorithm for initiation of the traction enhancement system is only active when the ABS is triggered. A typical algorithm is shown in Figure 6. There is also provided, in addition or alternately, for a signal from an early warning brake light system sensor to be used, which is described in more detail in the applicants South African provisional patent application 2010/02253, the contents of which is incorporated herein by reference.

A product commercially known as VHT Trackbite® has been identified as one suitable traction enhancement compound. This compound is often applied onto a starting point of roads at drag races, in order to improve the grip of the tires when the vehicle is exerting maximum torque. This product can .be used on wet or dry surfaces, is biodegradable, not harmful to the environment and relatively inexpensive. This compound is dissolved in lsopropyl alcohol or ease of distribution, but is not sticky until the lsopropyl alcohol has evaporated. Once the lsopropyl alcohol has been evaporated the compound becomes a sticky, high-viscosity gel-like substance which is not easily conveyed through conduits, nozzles and the like. Various discharge approaches may therefore be utilized. In one embodiment the Trackbite may be dissolved in a suitable solvent as is described above. In another embodiment it may also be possible for the compound to be packaged in frangible shells, similar to that used for paint ball capsules. The packaged compound can then be shot onto the target surface, and once. the tires drives over the shells, or upon impact of the shells with the target surface, the compound will be exposed, and will come into contact with the tread of the tire and the road surface.

It will be appreciated that the above are only two embodiments of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention. For example, although the example only shows the traction enhancement system being used on the front wheels of the vehicle, it will be appreciated that the same concept can be applied to the rear wheels, or to both the front wheels and the rear wheels.

It is believed that that above invention will at least partially meet the stated objectives, but it will also be appreciated that the invention as described above will not work on surfaces such as sand or ice.

Claims

CLAIMS:

1. A traction enhancement system, suitable for use with a means of transportation in order to improve traction between a tire of the means of transportation and a surface on which the means of transportation is used, the traction enhancement system including: a delivery system suitable for delivering a traction enhancement compound onto a target surface where increased traction is required; and a control system adapted to determine if a collision between the means of transportation and an external object is probable, and to cause the delivery system to be actuated, in order for the delivery system to deliver the traction enhancement compound onto the target surface.

2. The traction enhancement system of claim 1 wherein the delivery system includes a reservoir for in use containing the traction enhancement compound, and an ejector adapted to deliver the traction enhancement compound onto the target surface.

3. The traction enhancement system of claim 2 wherein the ejector is in the form of a nozzle having a first end being in flow communication with the reservoir, and a second end being directed towards the target surface, and through which the traction enhancement compound can be expelled onto the target surface.

4. The traction enhancement system of claim 2 or claim 3 in which the reservoir includes a receptacle having an inlet for receiving the traction enhancement compound, and an outlet being in flow communication with the nozzle.

5. The traction enhancement system of claim 4 wherein a flow control valve is provided between the outlet of the reservoir and the nozzle.

6. The traction enhancement system of any one of claims 2 to 5 wherein the reservoir also includes a heat transfer arrangement for effecting heat transfer between the traction enhancement compound in the receptacle and a heat transfer medium.

7. The traction enhancement system of claim 6 wherein the heat transfer arrangement comprises an inlet for receiving the heat transfer medium, an outlet for discharging the heat transfer medium, and heat transfer passage extending between the inlet and outlet, the heat transfer passages being configured to enable heat transfer between the heat transfer medium and the traction enhancement compound.

8. The traction enhancement system of claim 6 or 7 wherein the heat transfer medium is in the form of water used in an engine arrangement of the means of transport.

9. The traction enhancement system of claim 8 wherein the inlet of the heat transfer arrangement is in flow communication with water from an inlet of a radiator of the engine arrangement, and the outlet of the heat transfer arrangement is in flow communication with an outlet of the radiator.

10. The traction enhancement system of any one of claims 7 to 9 in which the heat transfer arrangement includes a flow control valve for controlling flow of the heat transfer medium through the heat transfer passages.

11. The traction enhancement system of any one of claims 2 to 10 wherein the reservoir includes a pressure sensor.

12. The traction enhancement system of any one of claims 2 to 10 wherein the reservoir includes a temperature sensor.

13. The traction enhancement system of any one of the preceding claims in which the control system includes proximity sensing means for sensing the distance between the front of the vehicle and another external object.

14. The traction enhancement system of any one of the preceding claims in which the control system is in communication with an ABS system forming part of the means of transportation.

15. The traction enhancement system of claim 13 or claim 14 wherein the control system uses signals from the ABS system and the proximity sensing means as input, calculates whether traction enhancement deployment conditions exist, and sends an actuating signal to the solenoid valve if such condition indeed exists.

16. The traction enhancement system of claim 15 wherein the calculations include calculating relative displacement, relative speed and relative acceleration between the vehicle and the external object.

17. The traction enhancement system of any one of claims 13 to 16 in which the control system receives a signal from a early warning brake light sensor.