WO2003076213A1

WO2003076213A1 - Friction device for vehicles

Info

Publication number: WO2003076213A1
Application number: PCT/NO2003/000081
Authority: WO
Inventors: Tom Grimset
Original assignee: GRIT SERVICES AS
Current assignee: GRIT SERVICES AS
Priority date: 2002-03-12
Filing date: 2003-03-07
Publication date: 2003-09-18
Anticipated expiration: 2004-09-12
Also published as: NO20021227L; AU2003212713A1; NO20021227D0

Abstract

Friction device for vehicles, wherein the friction device is placed to be in contact with one wheel (1) of the vehicle, preferably a wheel with traction. The friction device comprises at least one transmission device (11), one guide device (10) and at least an endless belt (5) with friction characteristics. The transmission device (11) is brought into contact with the wheel of the vehicle (1) and the belt(s) (5). The belt(s) (5) is/are organised around the guide mechanism (10), which belt (5) is in contact with the surface where the wheel (1) is driving.

Description

FRICTION DEVICE FOR VEHICLES

The present invention relates to a friction device for vehicles.

The purpose of present invention is to achieve a cost effective device for improving the traction of a vehicle at low speeds and under especially difficult driving conditions; conditions of a type that would normally prevent traction.

The purpose is to provide equipment that has functionality similar to that of snow chains, but with facilities for activation/deactivation from the driver's seat by means of simple control devices located on the control panel. The equipment is intended for temporary activation during particularly difficult situations and is not intended for permanent operation.

These objectives are achieved by means of the independent claim 1 of the invention and by means of the embodiments in accordance with the dependent claims 2-10.

The invention especially concerns vehicles with back wheel traction

(including 4 wheel drives), but will also be suitable for vehicles with front wheel traction. The invention comprise devices, typically one per back wheel, to which traction power is transmitted from the rubber surface of the traction wheels of the vehicle, and contribute to the traction of the vehicle by further transforming this power into a force onto the vehicle in the chosen direction. The friction devices include typically a plurality of sharp, metallic elements designed to penetrate the surface of the road whenever that surface consists of snow or ice. It is further a purpose of the invention to increase the contact area between the vehicle and the road surface, thus further improving traction.

The friction devices are intented for use at low speeds only, speeds typically achieved when a commercial vehicle is running at the lowest gear ratio or in reverse. The friction devices are intended to operate in a manner similar to the caterpillars of a bulldoser or a military tank.

The driver activates the friction devices manually by means of a control system, which has features similar to the control systems for the operation of various auxiliary equipment on trucks and tractors. The driver decides when the connection or the disconnection of the friction devices is suitable. The invention typically consists of the following components:

- Friction devices

- Control system - Operator panel

- Interface to the chassis of the vehicle

- Interface to the electrical battery of the vehicle and/or any possible/hydraulic pneumatic power system

A typical limitation of the invention is that any embodiment put into practice will require so much ground clearance that it will probably be limited to vehicles that are designed with such clearance, i.e. typically busses, trucks, large vans and pickup trucks. In addition the invention is not very practical for adapation to vehicles that have traction on the front wheels only.

The friction device may be mounted on to vehicle equipped with studded tyres or winter tyres of the unstudded type. Thus it is no intention of the invention to replace studs; the latter being used at all speeds relevant for transport in winter.

Some combinations of topography and climate present challenges related to driving in winter.

Conditions characterised by deep snow, wet or dry ice, or "black ice" (thin layer of ice forming when the wet asphalt freezes ) may require auxiliary equipment such as snow chains. This may be the case both for vehicles equipped with studs and with tyres with soft surface.

In urbane areas and major motorways the driving conditions are acceptable most days of a winter, in as much as extensive use of salt and gravel provide the essentially required friction between the tyres and the road surface.

However, most drivers in such areas also experience that certain, fairly, short pieces of the road may cause trouble, for instance smaller roads to private villas. The use of studs is solving some of these problems, but at extreme conditions they have limitations. They are, for instance, of limited utility in deep snow.

Thus there is a need for further improvement of the traction for vehicles operating under especially difficult combination of demanding road surface and topography. This particularly applies to vehicles that operate periodically in difficult areas, but which travel substantially on salted roads, e.g. city busses, ambulances and fire trucks. For certain vehicles of these categories it is not practical to stop the vehicle for the purpose of fitting on snow chains. For certain kinds of emergency vehicles the delay caused by this kind of operation is particularly undesirable.

The present invention concerns a device that is cost-effective and performs the same function as snow chains, where the only difference is that they may be activated/deactivated from the drivers seat at low vehicle speed, such that the inconvenience of fitting on and removing the chains manually is avoided.

The activation of the friction device fitted on to a typical city bus, running 99% of the schedule route in problem free areas, may typically be required in order to overcome a hill climb on an early morning when there has been a lot of snow and before the city authorities have prepared the road for transport.

Prior art includes a great collection of patents from 1915 onwards. Very few have been commercialized. Generally it may be stated that any device including mechanical components of any mass fixed permanently to the wheel or tyre will be subject to severe disadvantages. Balancing a wheel is demanding in itself and with additional mechanical devices in rotation, such an arrangement will be brought into natural oscillations at some speeds, and cause oscillations/vibrations that at least are unpleasant, at worst they may be destructing the vehicle and jeopardize the road safety.

US 4906051 , US 2250713, US 2256469, US 2241849, US 1514431 , EP 236041 are cited as examples of the prior art.

As may be seen from these descriptions these embodiments have just the same disadvantages as described above. It is admitted that this list of references is far from complete to be able to describe the state of prior art, but should be considered as illustrating examples of previous work.

One prior art device of interest, which is offered commercially as an option/standard on heavy trucks with traction only on the foremost of the two rear set of wheels, wherein a metal wheel is arranged to be movable above the centre line between the wheels in the boggie-set, and can be steered by remote control to be moved vertically downwards to establish a rotating contact between the set of wheel to make both pairs traction. Thus use of an auxiliary wheel for the purpose of transmitting power from one traction wheel to another is well established and demonstrated to be practical for short periods. This technology offers no solution for the case of low friction between the tyres of the wheels and the road surface, only a distribution of traction on various wheels.

Drawings are organized as follows:

Figure 1 is a sketch showing on a principle basis the main components of the system Figure 2 is a sketch illustrating activation/deactivation of the device

Figure 3 is a sketch illustrating the forces of the system when activated

Figure 4 is a sketch of the friction element

Figure 5 is a side view of a preferred embodiment of the mechnaical arrangement Figure 6 is a sketch from above of Figure 5

Figure 7 is another side view of Figure 5

Figure 8 is a 3 D representation of Figure 5

Figure 9 is schematically showing a preferred embodiment of a hydraulic control system Figure 10 is a 3 D representation of Fig 3

In the following text all the figure references are described:

1 is one out of two or more of the wheels of a vehicle, preferably the traction wheel of the vehicle, typically a vehicle with good ground clearance, for instance a buss or a truck. 11 is a transmission device comprising a single or a plurality of wheels or roller devices, typically made from rubber or a material of similar characteristics. The guide device 10 comprises a single or a plurality of roller devices such as e.g. wheels or rollers. In a preferred embodiment the guide device comprises a set (typically3) of roller devices or wheels that are in contact with 11 but not with 1. Alternatively the guide device may be constituted of a continuous body, which to a certain extent is long and curved and adapted such that at least one belt may be arranged around the body. The body may for instance be curved so as to make the contact between the transmission device 11 and the body possible, and possibly between the belt and the transmission device. In one embodiment such a body may be coated with a teflon type material.

5 is a belt with studs or a number of serrated/profiled steel wires (as suggested in Figure 8) or similar device designed for good grip with a slippery road surface.110 represents the friction element as a group and comprises 10,11 as well as an arrangement including a mechanical frame and suspension for 10 and 11 in one integrated mechanical unit, illustrated in Figure 8.

The group marked as 110 (ref fig 4) may be controlled to travel along a track/path, typically forming a 45 degrees angle with respect to the road surface, as illustrated in figure 2, so that the belt 5 engages both the road surface and the tyre of the traction wheel 1. When the control system operates the friction device 110 to engage both the road surface and the tyre of the traction wheel, frictional forces will be transmitted from the traction wheel via the transmission device 11 , such as for instance a wheel, and the guide device 10, such as for instance a wheel, and belt/wire 5 so that the vehicle is exposed to a force in the same direction as the wheel is travelling/moving.

110 may in principle be mounted in front of, or behind, the traction wheel 11 , the choice is likely to depend on the technical/geometrical limitations of a given vehicle. However it is essential that the friction element 110 is moved out of the path/track of the traction wheel in the deactivated condition so that splash flying off the tyre as seldom as possible hits the friction element.

Figure 3 illustrates how the friction element as a group 110 has one component of force 107 that effects the traction wheel 1 and one component of force 108 effecting the road surface. The friction belt/wire 5 is in contact with the road surface and that the friction between belt/wire and the road surface will determine the transmission of force when the friction element is activated. It is assumed that this element only is activated on occasions when the natural friction between traction wheel 1 and the road surface is particularly low.

For vehicles equipped with a differential brake or differential lock it will be detrimental to activate the friction element 110 for cases where the natural friction between traction wheel and road surface is high, for instance, on dry asphalt. The driver of the vehicle is required to fully understand this mechanism.

A more complex embodiment also makes it possible to provide the described device with protection mechanisms against such erroneous use, but for the preferred embodiment, primarily intended for utility vehicles operated by professionals, such protection devices are not considered to be necessary.

The group 110 is suspended rotatably in a point on the chassis, and rotate on a robust surface designed to accommodate significant moments/mechanical forces via a mechanical arm/lever 3. The lever itself may function as a resilient element and transmits a moment to 6 by means of a spring element 9 which makes contribution so that the group 110 orients itself against the road surface with full contact on the entire surface. The mechanical lever 3 is driven to an end-of-travel position 12 that prevent group 110 from being driven too far under the traction wheel in a situation where there may temporary be low weight on the traction wheel, e.g during driving on a particularly bumpy surface.

A hydraulic actuator 8 is suspended in the chassis at point 7. The actuator may also be elctromechanical or pneumatic, but it is preferred hydraulic in a preferred embodiment for a typical heavy vehicle.

The friction element 110 comprises the transmission device 11 and the guide device 10 as well as belt or wire are arranged so that belt/wire is pretensionsed by means of a simple spring arrangement (not shown). Bearings for rotation of 10 and 11 may be simple, low cost sleeve bearing with simple grease lubrication. The device is only intended to be used for short periods of time and at low speeds, i.e. heat dissipation and efficiency are not essential objectives. Such a design may also offer robustness with respect to water and particle contamination from the road.

Figure 9 shows the main features of a hydrualic control circuit designed to control the lever 3 and thus the group 110. The control system may be designed in a number of ways depending on how other auxiliary systems are arranged on the given vehicle. On the heavy utility vehicles there are often both pneumatic and hydraulic auxiliary systems, while all vehicles have at least one electrical auxiliary system. The control system as described is based on the latter case and is based on a simple interface with the electrical auxiliaries of the vehicle i.e. the starting battery.

217 is an electrically driven hydraulic pump that supplies hydraulic pressure to the hydraulic accumulator 214. The pump continues to supply until a predefined pressure level is reached, this is detected by means of a simple, commercial pressure switch (not shown). 216 is a safety valve. 205 is a directional switching valve activated by means of a switch on a panel located at the drivers seat in the vehicle. Upon activation of the valve the oil flows under pressure into the cylinder 8, which has pressure side 201 , return spring 202 and piston rod 203. 207 is a hydraulic conduit connecting the spring chamber with the return circuit of the hydraulic system. 209 is a filter, 210 is a relief valve to drain the pressure. 218 is the hydraulic reservoir. This system may be configured in a number of ways. Together with a simple electromechanical control system consisting of circuit switches and relays (not shown), which is found in corresponding design in one form or another on all relevant vehicles, a control of the cylinder may be achieved, and thus also of the group 110 so that the friction elements are brought to engagement or out of engagement according to the considerations of the driver.

The driver's judgement is a key factor. If a friction device as described was to be fitted on to a standard vehicle, which may be used by any certified driver, it would require additional safety devices, e.g. interlocks preventing activation at high vehicle speeds. Such as task is manageable as such, but requires additional instrumentation and further interfaces with the vehicle.

Such instrumentation is not described. The invention is primarily intended for special vehicles (typically busses, ambulances, wrecker trucks or fire trucks), which are typically driven by professionals, capable of considering when to activate and deactivate.

A panel with control switches for switching the system on and off and activating the device. Such panels with relay control are commonplace on all vehicles and do not represent any new features. Thus they are not described.

As an option the force with which the friction device is activated may be made adjustable from the panel. This may be performed by regulating/controlling the pressure in the cylinder. Equipment required to achive this function is commonplace and thus not described.

Claims

1. Friction device for vehicles, which friction device is placed to be in contact with one wheel (1 )of the vehicle, preferably a traction wheel, characterized in that the friction device comprises at least one transmission device (11 ), one guide device (10) and at least an endless belt (5) with favourable friction characteristics, wherein the transmission device(s) (11 ) is brought into contact with the wheel of the vehicle (1) and the belt(s) (5), further that the belt(s) (5) is/are arranged around the guide device (10) , which belt(s) (5) is in contact with the surface where the wheel (1 ) is driving/rolling.

2. Friction device in accordance with claim 1 , characterized in that the guide device (10) comprises one or more, preferably three, roller devices e.g. wheels, and/or that the guide device (10) is constituted of a continuous body where portions of the body has a curved shape.

3. Friction devices in accordance with claim 1 or 2, characterized in that the friction device comprises a plurality of belts (5) arranged in a parallel relationship around the guide device (10).

4. Friction device in accordance with one of the claims 1 -3, characterized in that the transmission device (11 ) is constituted of a number of rolling devices e.g wheels, rolls.

5. Friction devices in accordance with one of the claims 1-4, characterized in that the belt (5) is provided with sharp metallic elements e.g. studs, steel wires with a rugged profile, or made from a material providing high friction with the surface.

6. System to activate the friction device in accordance with one of the claims 1-5, into engagement or out of engagement with the wheel(s) of the vehicle characterized in that the system comprises a lever (3) whereby the friction device is attached to one end of the lever by means of a spring element, and that the other end of the lever is rotatably fixed to a first point (6) in the chassis of the vehicle, wherein a stopping device (12) is arranged in proximity to the other end of the lever such as to limit the movement of the lever (3), and further that one end of an actuator (8) is rotatably suspended in a second point (7) in the chassis, while the other end of the actuator is fixed to the lever (3)

7. System in accordance with claim 6, characterized in that a control system is connected to an operator panel which possibly is controlled from the drivers seat, renders engagement/disengagement of the friction device with the wheel(s) of the vehicle.

8. System in accordance with claim 7 or 8, characterized in that the actuator (8) is a hydraulic, electromechanical or pneumatic cylinder.

9. Method for activation of the friction device according to claims 1 -8 to operational mode by bringing it into contact with one wheel of the vehicle, characterized in that a signal is transmitted via the control system from the control panel at the drivers place to command the friction device into engagement with the wheel of the vehicle, thereby activating the actuator (8) and thereby initiating the movement of the lever (3) so that the friction device is taken into engagement with the wheel (1 ), wherein the wheel (1 ) of the vehicle transmits movement to the transmission device (11 ) and further to the belt (5) so that the force contribution which is obtained by the frictional forces between the belt (5) and the surface contributes to traction of the vehicle.

10. Use of the device according to one of the claims 1 -5 at low speeds on a variety of vehicles.