Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/0311—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation
  • B60C11/0316—Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation further characterised by the groove cross-section

Definitions

• the present invention relates to a farm vehicle tyre.
• a farm vehicle tyre has a tread having a toroidal base surface extending about a central axis of rotation; and a number of lugs extend radially upwards from the base surface, and each have a front wall and a rear wall with respect to a given rolling direction.
• each lug With respect to a plane perpendicular to the axis of rotation are linear and converge outwards, so that each lug has a trapezoidal section with respect to a plane perpendicular to the axis of rotation.
• Patent Application JP-7032820-A proposes a farm vehicle tyre in which the leading edge of the section of each lug in a plane perpendicular to the axis of rotation is a cycloid.
• Patent Application EP-0903249-A1 proposes a farm vehicle tyre in which the leading edge of the section of each lug in a plane perpendicular to the axis of rotation comprises a curved bottom portion and a straight top portion.
• Figure 1 shows a schematic front view of a portion of a farm vehicle tyre in accordance with the present invention
• Figure 2 shows a schematic side view of part of the Figure 1 tyre
• Figure 3 shows an enlarged detail of Figure 2.
• Number 1 in Figure 1 indicates as a whole a farm vehicle tyre comprising a tread 2 having a toroidal base surface 3 extending about a central axis 4 of rotation.
• tyre 1 rotates about axis 4 of rotation, and rolls on soft ground 9 defining a rolling surface.
• base surface 3 contacts ground 9, which is therefore tangent to base surface 3; whereas lugs 5 sink into ground 9, and form in ground 9, by compression, holes 10 negatively reproducing the shape of lugs 5.
• Lugs 5 are essential to enable tyre 1 to advance along ground 9, by the traction of tyre 1 depending solely on interaction between lugs 5 and ground 9. That is, the total traction of tyre 1 equals the sum of the horizontal components (i.e. parallel to ground 9) of the interaction forces generated between lugs 5 and ground 9. As shown in Figure 3, each point on the leading edge 11, with respect to rolling direction 8, of the section of each lug 5 in any plane 12 ( Figure 1) perpendicular to axis 4 of rotation generates, with respect to ground 9, an interaction force F directed perpendicularly to leading edge 11.
• Leading edge 11 is in the form of an involute curve outward of base surface 3 (an involute curve is the locus of the points for which, at each point on the curve, the perpendicular to the curve is tangent to the base circle) .
• an involute curve is the locus of the points for which, at each point on the curve, the perpendicular to the curve is tangent to the base circle.
• only a portion of leading edge 11 may be in the form of an involute curve.
• This provides for superior traction of tyre 1, by maximizing the total traction of tyre 1, while at the same time eliminating any interaction force F between lug 5 and ground 9 having an upward vertical component (i.e. perpendicular to ground 9) .
• An interaction force F between lug 5 and ground 9 having an upward vertical component is particularly damaging, by in no way contributing to traction, and by lifting and subsequently detaching part of ground 9, thus reducing the contact area between lug 5 and ground 9.
• an interaction force F between bar 5 and ground 9 having a downward vertical component is not particularly damaging, by simply compressing and compacting ground 9.
• the involute curve shape of leading edge 11 of the section of each lug 5 is formed outward of base surface 3, assuming base surface 3 is perfectly cylindrical.
• the involute curve shape of leading edge 11 of the section of each lug 5 is formed outward of base surface 3, assuming base surface 3 is flattened at a contact area with ground 9.
• leading edge 11 is convex in shape, so that the perpendicular to leading edge 11 at each point of leading edge 11 located beneath rolling surface 9 has a direction in which any component perpendicular to the rolling surface is directed downwards .
• leading edge 11 of the section of each lug 5 along a plane 12 perpendicular to axis 4 of rotation is an involute curve outward of base surface 3, by eliminating interaction forces F having upward vertical components, while at the same time maximizing the overall traction of tyre 1.
• leading edge 11 of the section of each lug 5 is a broken line inscribed in an involute curve outward of base surface 3, or a broken line comprising a number of segments, each substantially circumscribing a convex surface of an involute curve outward of base surface 3.
• leading edge 11 of the section of each lug 5 is a broken line comprising a number of segments, each substantially inscribed in or circumscribing a convex surface of an involute curve outward of base surface 3.
• the broken-line embodiment is less satisfactory, by the interaction force F between lug 5 and ground 9 at times having an upward vertical component.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Tires In General (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35911096

Family Applications (1)

Country Status (7)

Families Citing this family (30)

Citations (3)

Family Cites Families (9)

• 2004
  • 2004-12-28 IT ITTO20040908 patent/ITTO20040908A1/it unknown
• 2005
  • 2005-12-27 US US11/794,345 patent/US9004123B2/en active Active
  • 2005-12-27 WO PCT/EP2005/057187 patent/WO2006069999A1/en not_active Ceased
  • 2005-12-27 ES ES05823600T patent/ES2306276T3/es active Active
  • 2005-12-27 DE DE602005006848T patent/DE602005006848D1/de active Active
  • 2005-12-27 EP EP05823600A patent/EP1831034B1/en active Active
  • 2005-12-27 JP JP2007548819A patent/JP4782146B2/ja active Active

Patent Citations (3)

Non-Patent Citations (1)

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