JPH0834209A - Pneumatic tire with lug - Google Patents

Abstract

PURPOSE:To prevent the deep digging of soil in a cultivated field by inclining the tip part of a side wall on the stepping on side of a lug at more than a fixed angle to a plane including the axial center of a tire, and connecting the tip part to a lug bottom through a scooping part. CONSTITUTION:A pneumatic tire 1 has a pair of right and left side walls 2; a crown part 3 which stretches from the side walls and extends over them; and a tread 4 where lug parts 5 extending incliningly to a peripheral direction from the central part of the crown part 3 toward a shoulder part are protrusively provided in a gradually expanding shape in the crown part 3 and arranged in a peripheral direction. In a side wall 6 o n the stepping on side of the lug 5, a scooping part 14 is provided from the tip end part 12 to the lug bottom 9. A plane to connect the end Q on the lug bottom side of the tip part 12 with the tip part P of the side wall 6 has a large inclination angle more than 30 degrees to a plane N including an axial center, and a space between the end part Q and the lug bottom 9 is connected through a scooping part 14. Thus a soil excluding ability can be improved, and a large buoyancy and traction can be produced to prevent the deepening of the tilled ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for agricultural land, for example, a pneumatic tire with lugs which is mounted on an agricultural tractor or the like and used for paddy field work and field work.

[0002]

2. Description of the Related Art Conventionally, pneumatic tires for agricultural lands have a rugged pattern in which a large number of C-shaped lugs are arranged on a tread surface in order to ensure running performance on mud and soft ground. There is. In addition, in agricultural applications, high rug patterns with high rug heights are the mainstream because they are often used for paddy field work. The side wall of the lug of this type tire is formed to have an inclination angle of about 20 degrees with respect to a plane including the tire axis, and the side wall on the step side of the lug obtains a traction force and is scraped off while running. The soil is discharged laterally from the rug ditch provided between the rugs.

[0003]

However, conventional pneumatic tires with lugs having a high rug pattern are manufactured mainly considering paddy field work, and therefore exhibit excellent traction, but only in paddy fields. In the field work, the soil was dug up to deepen the plow and the field was damaged.

The present invention is intended to eliminate the above-mentioned drawbacks, has an excellent floating force in the soil, suppresses the deep digging of the soil in the field, and has a high lag pattern and a high lag pattern. It is an object of the present invention to provide a pneumatic tire with a lug that can be operated while maintaining traction on a certain mud or soft ground.

[0005]

In order to achieve the above-mentioned object, the invention according to claim 1 has a pair of left and right sidewalls and a crown portion which is continuous from both sidewalls and extends between both sidewalls. A tread having a lug projecting in a V shape and extending in the circumferential direction from the central portion toward the shoulder portion side with respect to the circumferential direction, and a tip portion on the crown portion central side of the lug is first provided. Make a pneumatic tire with a lug in which the rotation direction of the tire is specified so that it touches the ground and the rear end of the shoulder side of the lug will lag, and in the lug cross-sectional shape on the cross section parallel to the equatorial plane of the tire, The side wall on the stepping side has a tip portion which is greatly inclined at an angle of 30 degrees or more with respect to a plane including the tire axis, and a goug portion radially inward from the tip portion, and the tip portion passes through the goug portion and a lug. It is connected to the bottom Pneumatic tire with a lug and said.

The invention according to claim 2 is the pneumatic tire with lug according to claim 1, characterized in that the height of the above-mentioned gouged portion is 0.2 to 0.5 of the lug height. .

[0007]

According to the first aspect of the present invention, a large number of lugs having a designated rotation direction are provided such that the front end of the crown center side comes into contact with the ground first and the rear end of the shoulder side comes into contact with the ground later. In the pneumatic tire with lugs arranged in the shape of, the lug cross-sectional shape on the cross section parallel to the equatorial plane of the tire, the side wall tip of the step side of the lug with respect to the surface including the tire axis Since it is inclined at a large angle of 30 degrees or more, and such a tip portion is connected to the bottom of the lug through the cutout portion, the capacity of the lug groove between the lugs is increased by the cutout portion to improve the soil removal performance. The tip of the soil compacts the soil downward, and the rug kicks the compacted soil to generate greater buoyancy and traction, and does not deepen the tiller. If the greatly inclined tip is directly connected to the lug bottom without providing a cutout, the lug spacing becomes narrow, the capacity of the lug groove between the lugs becomes small, mud clogging easily occurs, and the weight increases.

According to the second aspect of the present invention, the height of the above-mentioned cutout portion is 0.2 to 0.5 of the lug height, and when the height of the cutout portion is less than 0.2 of the lug height, mud clogging occurs. The effect of prevention and weight reduction is not satisfied, and when it exceeds 0.5, the levitation force and the traction effect by the tip portion are not satisfied.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The pneumatic tire 1 with a lug of the present invention is shown in FIG.
As shown in FIG. 2, a pair of left and right sidewalls 2 (only one of which is shown in FIG. 2), a crown portion 3 extending from both sidewalls 2 and extending between the sidewalls, and a central portion of the crown portion 3. There are treads 4 in which a plurality of lugs 5 extending in a circumferential direction from the shoulder portion to the shoulder portion side are provided so as to project in a V shape with the pattern center as a substantially central portion of the crown portion and are arranged in the circumferential direction. The lug 5 is formed so that when the tire rotates, the front end of the lug on the center side of the crown portion comes into contact with the ground first and the rear end of the lug on the shoulder side comes into contact with the ground later.

As shown in FIGS. 1 to 3, the lug 5 has a side wall 6 on the stepping side (direction of the tire rotation direction D) and a side wall 7 on the kicking side (direction opposite to the rotation direction D). In the lug cross-sectional shape (FIG. 3) in the cross section parallel to the equatorial plane of the tire, the side wall 6 on the stepping side of the lug 5 is inclined at its tip 12 with respect to the plane N including the tire axis at a large angle θ. Which is 47 degrees in this example.

On the step-side wall 6 of the lug 5, a cutout 14 is provided from the tip 12 to the lug bottom 9 side. When the lug bottom side end of the tip 12 is Q and the tip of the side wall 6 is P, the plane between P and Q has a large inclination angle θ of 30 degrees or more with respect to the plane N including the axis. However, the end portion Q and the lug bottom 9 are connected by the cutout portion 14. The end portion Q is also the height of the gouging portion, and the gouging portion height a represented by the vertical distance between the end portion Q and the lug bottom is A which is the vertical distance between the tip portion P and the lug bottom. Then, a = (0.2-
0.5) A range is set. With this cutout part,
The capacity of the lug groove 8 between the lugs is increased. As shown in FIG. 3, the undercut portion 14 is formed mainly by being connected to the lug bottom 9 by a curve having a radius R having a center of curvature on the adjacent lug side. The tire axial width W2 of the tread 4 provided with a large number of lugs 5 is set within a range not exceeding the tire sidewall width W1 to prevent the lugs 5 from collapsing the ridges. The operator runs the vehicle along the ridges using the width of the tire sidewall as a guide.However, if the lug is protruding from the sidewall, the rug will easily break the ridge, so arrange the lugs inside the tire side. ing.

Examples 1 and 2 based on the above example were manufactured as shown in Table 1, and the entire side wall on the stepping side was removed from the tire of each Example 1 and 2 except for the gouged portion, and the angle was substantially the same as the tip. Comparative tires similar to those of the respective examples were manufactured except that they were connected to the lug bottom 9 with the above, and the tests comparing them were conducted. In the first embodiment, the radius of curvature R that forms the cut-out portion is R.
Is 10 mm at the center-side tip portion 16 of the lug, and the radius of curvature R is made to increase toward the shoulder-side rear end portion 17, and the curvature radius at the shoulder-side rear end portion 17 is set to 80 mm. The same applies to the second embodiment, and the radius of curvature R is 10 mm at the front end portion 16 and 100 mm at the rear end portion 17. In the tires of the examples, mud clogging was reduced, the traction performance was improved by about 10% as compared with the comparative tires, and the tire weight was reduced by 5%. Here, the traction performance was measured by the following method and compared. Two tractors are connected via a load cell, test tires are attached to the rear wheels of the front tractor, the tractor behind the front tractor is slowed down and the traction generated by the front tractor is measured. . The force measured by the load cell is used as the traction, and the traction performance is good when the value of this traction is large.

[0013]

[Table 1]

[0014]

The tip of the step side wall of the lug has a large inclination angle, and a scooping portion is provided radially inward from the tip to enhance the soil discharging property and promote the flotation force and the soil compaction. Since it has excellent traction properties but does not cause excessive excavation of soil, it can be used as a pneumatic tire with lugs that is useful for both paddy field cultivation and field cultivation.

[Brief description of drawings]

FIG. 1 is a plan view of a pneumatic tire with a lug according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a pneumatic tire with a lug according to an embodiment of the present invention.

FIG. 3 is a partially cutaway sectional view showing a lug sectional shape on a section parallel to an equatorial plane of a tire with a lug according to an embodiment of the present invention.

[Explanation of symbols]

 1 Pneumatic tire with lug 2 Side wall part 3 Crown part 4 Tread 5 Lug 6 Side wall of lug stepping side 7 Side wall of kicking side of lug 8 Lug groove 12 Tip part of side wall of stepping side 14 Side wall of stepping side Part 16 Center-side tip of lug 17 Shoulder-side rear end of lug θ Angle of inclination of side wall of step D Tire rotation direction N Surface including tire axis W1 Axial width of tire sidewall W2 Axial width of tread C Tire equator

Claims (2)

[Claims] 1. A pair of left and right sidewalls and a lug extending from the central portion toward the shoulder portion and inclined with respect to the circumferential direction on a crown portion which is continuous from both sidewalls and straddles between both sidewalls. With a tread protruding in the shape of a letter and arranged in the circumferential direction, the rotation direction of the tire such that the tip of the crown center side of the lug comes into contact with the ground first and the shoulder side rear end of the lug comes into contact with a delay. In the specified pneumatic tire with lugs, in the lug cross-sectional shape on the cross section parallel to the equatorial plane of the tire, the side wall on the step side of the lug is large at an angle of 30 degrees or more with respect to the surface including the tire axis. A pneumatic tire with a lug, characterized in that it has a sloping tip portion and a scoop portion radially inward from the tip portion, and the tip portion is connected to the lug bottom portion through the scoop portion. 2. The height of the cutout is 0.2 of the lug height.
The pneumatic tire with lug according to claim 1, wherein the pneumatic tire has a lug of 0.5 to 0.5.