JP2009280066A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in drainage performance and reducing a rolling resistance. <P>SOLUTION: The pneumatic tire is equipped with: a tread part 1; a pair of side wall parts 2; a pair of bead parts 3; a carcass 5 which is toroidally extended between bead cores 4 in respective bead parts 3, and is comprised of at least one carcass ply which winds back respective side part portions from the inner side toward the outer side in the tire width direction around a bead core 4; a belt 6 which is disposed at the outer peripheral side of a crown area of the carcass and formed by two layers or more inclined belt layers made of a cord extending to the inclined direction with respect to a tire equatorial plane; and a tread rubber 9 disposed outward in the radial direction of the belt. A recessed part 10 continued circumferentially in a loop is formed on the belt 6 and the tread rubber 8 at least in one place in the tread width direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with reduced rolling resistance and excellent drainage performance.

  In recent years, development in consideration of environmental problems such as global warming has been actively carried out, and one example is the reduction in fuel consumption of automobiles. One means for achieving this is to reduce the rolling resistance of the tire, and various technical developments have been made conventionally.

  When a tire rolls under load, bending deformation, shear deformation, and the like occur in a tread portion, a sidewall portion, and the like, and energy loss occurs due to consumption of deformation energy as heat energy. This energy loss is particularly generated in the tread rubber disposed in the tread portion, and reducing this leads to a reduction in rolling resistance of the tire.

  Therefore, conventionally, for example, reducing the thickness of the tread rubber has been considered effective in reducing the rolling resistance. However, in this case, it is often difficult to dispose a groove having a sufficient depth, which is responsible for the drainage performance of the tire, or a sufficient wear life cannot be ensured.

  For this reason, in addition to the reduction of rolling resistance, other performance, particularly high drainage performance, is strongly demanded.

  Therefore, the present invention provides a pneumatic tire with reduced rolling resistance and excellent drainage performance.

  The pneumatic tire according to the present invention has a tread portion, a pair of sidewall portions, a pair of bead portions, and a bead core in each bead portion that extends in a toroidal shape, and each side portion around the bead core. A carcass made of at least one carcass ply rolled back from the inner side to the outer side in the tire width direction, and a cord disposed on the outer peripheral side of the crown area of the carcass and extending in a direction inclined with respect to the tire equatorial plane A belt formed of two or more inclined belt layers, and a tread rubber disposed radially outward of the belt, the belt and the tread rubber having at least one portion in the tread width direction. Thus, a concave portion that is continuous in an annular shape in the circumferential direction is formed.

  Here, the “concave portion” means that each of the belt and the tread rubber surface is recessed toward the tire inner peripheral side in the meridian cross section, and the contour shape of the recess is not only an arc shape, but also a square shape, etc. It can also be made into an angular shape.

  More preferably, in such a tire, the position of the edge in the width direction with respect to the maximum distance from the rim diameter line of the belt with respect to the belt width BW in the meridian section of the tire assembled to the applicable rim The ratio BD / BW of the drop height BD is set to a range of 0.01 to 0.04.

  Here, “applicable rim” means a rim defined by an industrial standard effective in the region where the tire is produced and used, and the industrial standard is, for example, JATMA (Japan Automobile Tire Association) YEAR in Japan. BOOK (European Tire and Rim Technical Organization) STANDARD MANUAL in Europe, and TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK in the United States.

“Assembled to the applicable rim” means that the tire is assembled to the applicable rim specified in JATMA, etc., and an internal pressure is not applied, or an extremely low internal pressure of up to about 30 kPa is applied to give the tire a fixed form. It shall mean the state that was done.
“Belt width” refers to the maximum width of the belt measured in the state of being assembled to the applicable rim.
“Maximum distance” refers to the maximum distance of the outermost belt layer.
The “outermost belt layer” refers to, for example, a radially outer belt layer of two inclined belt layers having a width substantially corresponding to the ground contact width when the tire is grounded.
“Grounding width” refers to the contact with the flat plate when the tire is mounted on the applicable rim specified by JATMA, specified pneumatic pressure, placed in a stationary state perpendicular to the flat plate, and a specified 80% load is applied. It shall be the maximum linear distance in the tire axial direction on the surface.
The “belt drop height” refers to the difference in the radial distance of the width direction edge position with respect to the maximum distance from the rim diameter line of the belt.

  Preferably, the concave portion is positioned on both sides of the tire equatorial plane.

  Preferably, the recess is positioned on the tire equator plane, or on each of the tire equator plane and both sides of the recess on the tire equator plane.

  Preferably, the ratio CD / BW of the maximum depth CD of the concave portion of the belt thickness center line to the belt width BW is set in the range of 0.02 to 0.15.

  Preferably, the ratio CW / BW of the maximum width CW in the tread width direction of the concave portion of the tread surface with respect to the belt width BW is set in a range of 0.05 to 0.25.

By the way, the ratio CSWh / CSH of the radial distance CSWh to the maximum width position of the carcass to the radial distance CSH from the rim diameter line to the maximum radius position of the carcass may be in the range of 0.6 to 0.9. preferable.
Here, the “maximum radial position of the carcass” refers to the maximum radial position of what is positioned on the outermost side of the carcass ply constituting the carcass.

  Preferably, the ratio SWh / SH of the radial distance SWh from the rim diameter line to the maximum width position of the tire with respect to the tire cross-section height SH is set in the range of 0.5 to 0.8.

  Preferably, the ratio BW / CSW of the belt width BW to the maximum carcass width CSW is in the range of 0.8 to 0.94.

  Preferably, the ratio TD / (BW / 2) of the fall height TD between the maximum radius of the tread tread surface and the tread ground contact edge with respect to the belt half width BW / 2 is in the range of 0.06 to 0.145. And

Preferably, the position of the carcass corresponding to the edge in the width direction of the carcass to the maximum width position with respect to the path length CSP of the carcass pass line extending from the intersection of the carcass with the tire equatorial plane to the inner periphery of the bead core. The ratio CSL / CSP of the path length CSL of the path line is set to a range of 0.1 to 0.25.
The “carcass pass line” refers to the path of the thickness center line of the main body portion of the carcass, and does not consider the turn-up portion of the carcass with respect to the bead core.
The “position corresponding to the edge in the width direction of the belt of the carcass” refers to a position where the normal line standing at the edge in the width direction of the belt intersects the center line of the thickness of the carcass.

  It is also preferable that the distance from the rim diameter line at a position 0.8 times the maximum width CSW of the carcass, measured by the tread portion and sandwiching the tire equator plane, is 0.91 to 0. 0 of the tire sectional height SH. The range is 97 times.

Preferably, the belt swing angle at the end in the width direction of the belt is in the range of 0 to 10 °.
Here, the “belt swing angle” refers to the tire in each of the tangent line passing through the edge of the outermost layer and the tangent line at the edge position of the innermost layer of the belt layer constituting the belt as seen in the cross section of the tire meridian. The average value of the angle with respect to the line segment parallel to the central axis line shall be said.

In conventional tires, if the thickness of the tread rubber is reduced in order to reduce rolling resistance, it is difficult to arrange grooves with sufficient depth, and both drainage performance and reduction in rolling resistance can be achieved. There wasn't.
On the other hand, in the present invention, the belt and the tread rubber are formed at least at one place in the tread width direction by forming a concave portion that is annularly continuous in the circumferential direction. By increasing the bending rigidity, it is possible to effectively reduce the amount of deformation of the stepped part and the kicking part in the tread contact area, thereby effectively reducing the rolling resistance caused by energy loss due to deformation of the tread part. Can be reduced.
On the other hand, by forming a recess on the tread rubber surface and providing an annular groove with sufficient depth and width that continues in the circumferential direction of the tread, it ensures excellent drainage when traveling on wet road surfaces. Thus, the hydroplaning performance and the like during high speed running can be greatly improved.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a meridian cross-sectional view of a tire, showing an embodiment of the pneumatic tire of the present invention in a state assembled to an applied rim.

  In the figure, 1 is a tread portion, 2 is a pair of sidewall portions extending radially inward continuously to the respective side portions of the tread portion 1, and 3 is a radially inward direction of the sidewall portion 2. The continuous bead portions are shown in FIG.

  Here, for example, a single carcass in which each side portion of the carcass ply is laid around the pair of bead cores 4 and wound from the inside to the outside in the tire width direction. Two or more rubber-coated belt layers in which the belt cord extends in an orientation inclined at an angle of, for example, 20 to 30 ° with respect to the tire equator plane on the outer peripheral side of the crown region of the carcass 5 made of ply, Then, a belt 6 composed of two inclined belt layers is disposed, and such a belt 6 is composed of a rubber-coated cord extending substantially along the tire equatorial plane, for example, one belt reinforcing layer. 7 and a tread rubber 9 forming a tread surface 8 are sequentially arranged.

  Further, in this tire, the belt 6 and the tread rubber 9, and also the carcass 5 in the figure, are arranged at least at one place in the tread width direction, for example, on the tire equatorial plane and continuously annularly in the circumferential direction. The recess 10 is formed.

  In such a pneumatic tire, preferably, the falling height of the edge position in the width direction with respect to the maximum distance from the rim diameter line of the belt 6 with respect to the belt width BW, that is, the maximum of the outermost belt layer of the belt 6. The ratio BD / BW of the radius and the radial difference BD between the maximum radius of the belt 6 and the edge in the width direction is in the range of 0.01 to 0.04, more preferably in the range of 0.02 to 0.035. And

By adopting such a configuration, in addition to the above, the belt 6 is flattened.
In conventional tires, the difference in diameter of the shoulder region compared to the center region is large, so the belt near the shoulder region is stretched in the tire circumferential direction by panda graph movement when the tire rolls. Since it shrinks in the direction, the shear deformation of the tread rubber 9 within the meridian section is promoted.
On the other hand, in the above-described configuration, the belt 6 is flattened in the tread shoulder region, and the tread portion 1, particularly the curved belt portion near the shoulder region, is stretched flat at the time of grounding. Since the belt 6 is flattened and the diameter difference BD of the belt 6 is reduced, the belt 6 in the vicinity of the shoulder region is less extended in the tire circumferential direction, and shear deformation of the tread rubber 9 can be suppressed.
As a result, energy loss caused by deformation of the tread rubber 9 can be suppressed, and rolling resistance resulting from the deformation can be reduced.
Moreover, here, in combination with the fact that the bending deformation of the tread portion 1 bent at the stepping portion and the kicking portion of the ground contact portion can be effectively suppressed when the tire rolls under the formation of the concave portion 10. Energy loss can be further reduced.

  Preferably, the recesses 10 are arranged on both sides of the tire equatorial plane, preferably the recesses 10 are arranged on the tire equatorial plane.

  With this configuration, the concave portion 10 is disposed at a position where the ground contact pressure is highest when the tire rolls, and the rolling resistance can be further greatly reduced.

  Or it arrange | positions on each of the both sides of the recessed part 10 on a tire equator surface and a tire equator surface.

  With this configuration, it is possible to further improve the out-of-plane bending rigidity of the belt 6 in the radial direction, and to provide a plurality of wide grooves in the tread portion 1, thereby improving drainage performance.

  Preferably, the maximum depth of the concave portion of the thickness center line of the belt 6 with respect to the belt width BW, the maximum radius of the thickness center line of the belt 6 in the figure, and the radial difference at the intersection of the thickness center line and the tire equatorial plane. The CD ratio CD / BW is set to a range of 0.02 to 0.15.

  With this configuration, reduction in rolling resistance and drainage can be achieved at a higher level.

  That is, if the CD / BW is less than 0.02, the effect of improving the rigidity by the recess 10 cannot be sufficiently obtained. If the CD / BW exceeds 0.15, there is a risk that poor appearance occurs frequently on the surface of the recess during manufacture.

  Preferably, the ratio CW / BW of the maximum width CW in the tread width direction of the recess 10 of the tread tread surface 8 with respect to the belt width BW is set in a range of 0.05 to 0.25.

With this configuration, high drainage performance can be ensured.
That is, if CW / BW is less than 0.05, there is a concern about drainage performance. On the other hand, if it exceeds 0.25, the groove width of the tread rubber 9 becomes too wide and the ground contact area is reduced. There is a tendency for steering stability to decrease.

  Preferably, the radial distance from the rim diameter line to the maximum radial position of the carcass 5, the ratio CSHh to the maximum width position of the carcass 5 relative to the distance CSH to the adjacent region of the recess 10 in the figure, CSWh / CSH Is in the range of 0.6 to 0.9, and more preferably in the range of 0.7 to 0.8.

  With this configuration, the carcass line near the tread tread surface 8 has a locally bent region, and the bending rigidity is reduced in this portion. Due to the large deformation, the deformation of the tread portion 1 is reduced, and the shear deformation in the tire meridian section can be reduced by the tread portion 1.

  Preferably, the ratio SWh / SH of the radial distance SWh from the rim diameter line to the maximum width position of the tire with respect to the tire cross-section height SH is in the range of 0.5 to 0.8, more preferably 0. The range is from 6 to 0.75.

  With this configuration, the side rubber follows the carcass line, reduces energy loss inside the rubber, protects the carcass 5 when in contact with the curb, and can define the tire dimensions in the design of the vulcanization mold. .

  Preferably, the ratio BW / CSW of the belt width BW to the maximum width CSW of the carcass 5 is in the range of 0.8 to 0.94, and more preferably in the range of 0.84 to 0.93.

  With this configuration, the crown region is flat, the belt width can be set wider than usual, and shear deformation in the tire meridian cross section can be reduced.

  Preferably, the ratio TD / (BW / 2) of the fall height TD between the maximum radius of the tread tread surface 8 and the tread ground contact edge with respect to the half width BW / 2 of the belt 6 is 0.06 to 0.145. The range is more preferable, and the range is 0.075 to 0.095.

  This configuration is a regulation regarding the position of the tread surface directly above the belt 6, and the rubber thickness can be distributed without leaving a crown shape on the tread surface, thereby preventing uneven wear due to the diameter difference during contact.

  Also preferably, the position of the carcass 5 corresponding to the edge in the width direction of the belt 6 with respect to the path length CSP of the carcass 5 pass line from the intersection position of the carcass 5 to the tire equatorial plane to the inner periphery of the bead core 4. The ratio CSL / CSP of the path length CSL of the path line from to the maximum width position is in the range of 0.1 to 0.25, more preferably 0.12 to 0.18.

  This configuration defines the carcass length of the portion where the carcass 5 is locally bent, and optimizes the carcass length of the region in the method of obtaining a smooth curve connecting the carcass maximum width position and the point under the belt. Thus, a desired local deformation can be caused. The short carcass length in this region means that the direction is changed from the radial direction to the approximate width direction by the short length, so that the shape characteristic of being locally bent can be reinforced.

  Preferably, the distance from the rim diameter line at a position 0.8 times the maximum width CSW of the carcass 5 measured by the tread portion and sandwiching the tire equatorial plane is 0.91 to 0.97 of the tire cross-section height SH. The range is doubled, more preferably 0.92 to 0.96.

  In this configuration, the tread drop height at the position of 80% of the maximum tire width can be defined, and bending deformation in the meridian section of the tread and the belt portion can be suppressed. It should be noted that if the surface is completely flat, the ground contact pressure at the shoulder end is extremely increased and the uneven wear is worsened.

  Preferably, the belt swing angle θ at the end in the width direction of the belt 6 is in the range of 0 to 10 °, more preferably in the range of 3 to 7 °.

  In this configuration, the swing angle θ of the belt end is defined, and it is known that most of the shear deformation in the tire meridian cross section occurs on the outer side in the tire width direction. The end portion of the belt 6 can reduce shear deformation due to local curvature.

  By the way, it is preferable that the minimum radius of curvature of the carcass line between the maximum width position of the carcass 5 and the end portion in the width direction of the belt is 5 to 25 mm. That is, it is possible to define a radius of curvature when approximating a circular arc between the carcass maximum width position and the belt lower position, and it is possible to design a mold having the radius of curvature of this portion.

  Next, a tire having a structure as shown in FIG. 1 and having a size of 225 / 45R17 was prototyped, and the carcass is a carcass made of a cord twisted with polyethylene and arranged at an angle of 90 ° with respect to the tire equatorial plane. It consists of two layers of plies, and the belt consists of two layers of belts in which steel cords arranged at an inclination angle of 28 ° with respect to the tire equatorial plane are crossed between each other. Example tires 1 to 1 provided with a belt reinforcing layer having a structure in which a ribbon-like strip formed by coating a plurality of nylon cords with a spiral is spirally wound, as shown in Table 1, 7 and a structure sold in the market, and as shown in Table 1, Comparative Example Tire 1 with various specifications changed, and a structure as shown in FIG. Change the specifications of each The rolling resistance, the appearance defect rate, the wet performance, and the dry performance were measured for each of the modified comparative tires 2.

(Rolling resistance)
For each of Example tires 1 to 7 and Comparative example tires 1 and 2, the tires were assembled on a rim of 7.5 J, the filling internal pressure was 230 kPa, the load mass was 450 kg, and the tires were rolled at 80 km / h. The rolling resistance of the axle was measured and evaluated using a drum testing machine having a steel plate surface with a diameter of 1.7 m. The results are shown in Table 2 and FIG.
In addition, the index value in a table | surface is what used the value of the comparative example tire 1 as control, and shows that rolling resistance is so small that an index value is small.

(Appearance defect occurrence rate)
For each of Example Tires 1 to 7 and Comparative Example Tires 1 and 2, the proportion of tires in which appearance defects occurred in the tread central region at the time of tire production was evaluated by the defect occurrence rate (%) per 50 tires. . The results are shown in Table 2 and FIG.

(Wet performance test)
For each of Example tires 1 to 7 and Comparative tires 1 and 2, the tires were assembled on a 7.5 J × 17 rim, the filling internal pressure was set to 230 kPa, and mounted on a domestic FF vehicle with a displacement of 2000 cc. The road surface where water with a depth of 10 mm was accumulated on the road surface was gradually increased from 60 km / h, and the speed at which hydroplaning occurred was indexed and evaluated. The results are shown in Table 2.
In addition, the index value in a table | surface is calculated | required using the value of the comparative example tire 1 as control, and shows that wet performance is excellent, so that an index | exponent is large.

(Dry performance)
For each of Example tires 1 to 7 and Comparative Example tires 1 and 2, the tires were assembled on a 7.5 J × 17 rim, the filling internal pressure was set to 230 kPa, and mounted on a domestic FR vehicle with a displacement of 2500 cc. The driver ran on the test course and implemented a lane change at 150 km / h, a limit turn at 80 km / h, and acceleration from 50 km / h, giving a 10-point evaluation. The results are shown in Table 2.
In addition, if it is 7.5 points or more, it shows better performance compared to general tires on the market, and if it is 6.0 points or less, it shows a level at which it is judged that the performance is remarkably bad and there is no marketability. .

  From the results of Table 2 and FIG. 3, Example tires 1 to 7 were able to improve rolling resistance with respect to comparative tires 1 and 2. Moreover, Example tires 1-5 have a small appearance defect rate.

  Next, a tire having a structure as shown in FIG. 1 and having a size of 225 / 45R17 is manufactured as a prototype, and the carcass ply is composed of a cord twisted by polyethylene arranged at an inclination angle of 90 ° with respect to the tire equatorial plane. The inclined belt layer consists of two layers in which steel cords arranged at an inclination angle of 28 ° with respect to the tire equatorial plane are crossed between layers, and a ribbon-like ribbon coated with nylon cord on it As shown in Table 3, Example tires 8 to 14 in which a strip-shaped circumferential belt layer having a spiral wound structure is provided and various specifications are changed, and a structure sold in the market are provided. As shown in Table 3, the comparative tire 3 was changed in each specification, and the structure shown in FIG. 2 was compared. As shown in Table 3, each specification was changed. Example with tire 4 For each, rolling resistance, appearance defect rate, wet performance and dry performance were measured.

For each of Example tires 8 to 13 and Comparative tires 3 and 4, rolling resistance, appearance defect rate, wet performance, and dry performance were measured and evaluated by the above test methods. The results are shown in Table 4 and FIG.
The index values in the table of rolling resistance and wet performance are obtained by using the value of Comparative Example Tire 3 as a control. The rolling resistance is better as the index is smaller, and the wet performance is better as the index is larger. It was to show that

  From the results shown in Table 4 and FIG. 4, Example tires 8 to 13 were able to improve the reduction in rolling resistance compared to Comparative Example tires 3 and 4. In addition, Examples 8 and 9 were excellent in dry performance, Examples 10 and 11 were excellent in both dry and wet performance, and Examples 12 and 13 were excellent in wet performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a meridian cross-sectional view of a half portion of a tire in a state where an embodiment of a pneumatic tire of the present invention is assembled to an application rim. It is meridian sectional drawing about the half part of a tire in the state assembled | attached to the application rim, with the embodiment of the conventional pneumatic tire. It is the figure which showed the rolling resistance index | exponent and the tread appearance defect rate in an Example. It is the figure which showed the index | exponent of the wet performance and the dry performance in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass 6 Belt 7 Belt reinforcement layer 8 Tread tread 9 Tread rubber 10 Recessed part

Claims (14)

A tread portion, a pair of sidewall portions, a pair of bead portions, and a bead core in each bead portion extend in a toroidal shape, and each side portion is directed around the bead core from the inside to the outside in the tire width direction. A carcass made of at least one carcass ply rolled back and two or more inclined belt layers made of cords arranged on the outer peripheral side of the crown area of the carcass and extending in a direction inclined with respect to the tire equatorial plane In a pneumatic tire comprising a belt formed by the above and a tread rubber disposed radially outward of the belt,
A pneumatic tire characterized in that a belt and a tread rubber are formed with a concave portion that is annularly continuous in the circumferential direction at at least one location in the tread width direction.   Ratio BD / BW of the falling height BD of the edge position in the width direction with respect to the maximum distance from the rim diameter line of the belt with respect to the belt width BW in the meridian section of the tire assembled to the applied rim The pneumatic tire according to claim 1, wherein is in the range of 0.01 to 0.04.   The pneumatic tire according to claim 1, wherein the recess is located on both sides of the tire equatorial plane.   The pneumatic tire according to claim 1, wherein the concave portion is located on a tire equator plane.   The pneumatic tire according to any one of claims 1 to 3, wherein the recess is located on each of the tire equatorial plane and both sides of the recess on the tire equatorial plane.   The pneumatic tire according to any one of claims 1 to 5, wherein the ratio CD / BW of the maximum depth CD of the concave portion of the belt thickness center line to the belt width BW is in the range of 0.02 to 0.15. .   The ratio CW / BW of the maximum width CW in the tread width direction of the concave portion of the tread surface with respect to the belt width BW is in a range of 0.05 to 0.25. tire.   The ratio CSWh / CSH of the radial distance CSWh to the maximum width position of the carcass to the radial distance CSH to the maximum radius position of the carcass from the rim diameter line is in a range of 0.6 to 0.9. The pneumatic tire in any one of -7.   The ratio SWh / SH of the radial distance SWh from the rim diameter line to the maximum width position of the tire with respect to the tire cross-section height SH is in the range of 0.5 to 0.8. Pneumatic tire described in 2.   The pneumatic tire according to any one of claims 1 to 9, wherein a ratio BW / CSW of a belt width BW to a maximum width CSW of a carcass is in a range of 0.8 to 0.94.   The ratio TD / (BW / 2) of the fall height TD between the maximum radius of the tread tread surface and the tread ground contact edge with respect to the belt half width BW / 2 is in the range of 0.06 to 0.145. The pneumatic tire according to any one of 1 to 10.   The path line of the carcass from the position corresponding to the edge in the width direction of the belt to the maximum width position with respect to the path length CSP of the carcass pass line from the intersection position with the tire equatorial plane to the inner periphery of the bead core. The pneumatic tire according to any one of claims 1 to 11, wherein a ratio CSL / CSP of the path length CSL is in a range of 0.1 to 0.25.   The distance from the rim diameter line of the position of 0.8 times the maximum width CSW of the carcass that sandwiches the tire equatorial plane as measured at the tread portion is in the range of 0.91 to 0.97 times the sectional height SH of the tire. The pneumatic tire according to any one of claims 1 to 12.   The pneumatic tire according to any one of claims 1 to 13, wherein a belt swing angle at an end portion in the width direction of the belt is in a range of 0 to 10 °.

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