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US 6,506,134 B2Granted
Interlocking string network for sports rackets
OwnerFabio Paolo Bertolottiinventor
Life of this patent
Estimating the term…
Abstract
The invention is an improved sports racket comprising streamlined transversal strings and streamlined longitudinal strings with surface indentations that permit the strings to lock into other at the string crossings so the strings do not move with respect to each other and also stay oriented so as to minimize wind resistance during the swinging motion of the sports racket before and after ball contact. The invention includes a spacer for assembly of the strings in the sports racket incorporating a flexible body between the string and the racket frame for the absorption and restitution of part of the ball's kinetic energy during impact with the string to beneficially alter the feel of the strings.
Claims23
In combination with a sport racket having a frame with a handle, a throat connected to the handle, and a head connected to the throat, the head having an inner head surface enclosing an area to be spanned by strings, each of the strings having individual free ends, and an outer head surface opposite the inner head surface, the head further having a plurality of fixing means for securing the individual string free-ends to the frame, the improvement comprising:
- at least one string having a string enlarged section at only one free-end, and a regular string section, the string enlarged section having a cross-sectional area greater than the maximum cross-sectional area of the regular string section;
- the frame having a first cavity extending from the inner head surface to the outer head surface, the first cavity having a first opening on the inner head surface and a second, larger, opening on the outer head surface, the regular portion of the string being received in the first cavity with the regular string section protruding through the first opening, the first cavity restraining the string enlarged section from further movement into the first cavity beyond a predetermined advancement of the string enlarged section into the cavity;
- and
- a flexible spacer under compressive strain between the cavity and the string enlarged section, and having an elastic modulus and cross-sectional area that allow further compressive strain within the general recoverable stress-strain relation of the flexible spacer, the flexible spacer undergoing the further compressive strain to absorb and store at least a substantial part of the kinetic energy of an impact to the string, and the flexible spacer returning much of the stored energy to the string.
1 more element
A sport racket having a frame with a handle, a throat connected to the handle, and head connected to the throat, a plurality of strings, for transmitting energy, each string having a longitudinal axis and free-ends, the head having an inner head surface enclosing an area spanned by the strings, and an outer head surface opposite the inner head surface, the head having a passageway formed therein, and a fixing means for securing a free-end of one string to the frame, said fixing means comprising:
- an enclosured body within the passageway of the racket, the enclosure body receiving a string clamping member, the string clamping member having a wedge shaped outer surface and having another surface forming an inner passageway for receiving the string;
- and a pressing means, the pressing means having a wedged shaped bore for engaging the wedge shaped outer surface of the clamping member, thereby pressing the string clamping member against the string to restrain the string within said inner passageway.
A combination for fixing the free end of an individual string to the frame of a sports racket, said combination comprising:
- an enclosure body for frame attachment and extending through the thickness thereof, the enclosure body having a base surface and a cavity penetrating partially into the enclosure body, the cavity having a main opening and having a base surface within the enclosure body, the enclosure body further having a bore extending from the base surface to provide a second opening opposite the main opening and providing a passageway for the string through the enclosure body, the cavity receiving through the main opening;
- a pressing means having an outer surface and a wedge shaped bore extending the width of the pressing means, the wedge shaped bore enabling the string to be received in the pressing means, the wedge shaped bore receiving a string clamping member having a thicker end, the string clamping member having a wedge shaped outer surface and an inner passageway forming another surface for receiving the string within the string clamping member;
- the individual string being received, in order, in the enclosure body, in the string clamping member and in the pressing means;
- the string clamping member being lodged against the base surface of the enclosure body as the string clamping member engages the string in the cavity of the enclosure body, the string clamping member contracting in response to compressive force on the wedge shaped outer surface, the pressing means being received in the enclosure body and the string clamping member whereby the wedge shaped bore fits over the wedge shaped outer surface of the string clamping member and compresses the wedge shaped outer surface, the pressing means further having a locking means to block the string clamping member within the pressing means in response to the string clamping member of compression engaging the string.
1 more element
A sports racket comprising:
- a) a frame having a handle, a throat connected to said handle, and a head connected to said throat, said head defining a central opening, said head further having holes for receiving string;
- b) strings attached to said frame, each of said strings having ends received in respective one of said holes to enable said strings to span said central opening;
- c) at least one first fixing means for securing said strings to said frame, said at least one first fixing means having:
- an enlarged section formed only in one of said ends in at least one of said strings;
- at least one first of said head holes facing said central opening;
- and
- at least one second of said head holes generally opposite to said first opening, said first and second head holes accommodating said one of said strings within said frame, one of said string free-ends being received within said second hole, said first hole forming a cavity therein for engaging said string enlarged section when said string enlarged section is lodged within said cavity to establish a predetermined advance of said string enlarged section into said cavity whereby tension along said at least one string in the direction of the central opening causes said at least one string to be fixed to the frame;
- and a flexible spacer between the frame and the string enlarged section, the flexible spacer being made of a material exhibiting a recoverable stress-strain relation throughout the range of string tensions produced during operation of the racket, the range of string tensions applying compressive strains to the flexible spacer to enable a substantial part of the energy produced by the compressive string tensions to be stored by the flexible spacer, the flexible spacer returning much of the stored energy to the string.
5 more elements
A sports racket comprising:
- a) a frame having a handle, a throat connected to said handle, and a head connected to said throat, said head defining a central opening, said head further having cavities fully extending the width of said frame to produce openings for receiving strings;
- b) strings attached to said frame, each of said strings having ends received in a respective one of said cavities to enable said strings to span said central opening;
- c) at least one first fixing means for securing said strings to said frame, said at least one first fixing means having:
- an enlarged section formed only in at least one of said ends in at least one of said strings;
- and at least one of said cavities accommodating said one of said strings and engaging said string enlarged section when said string enlarged section is lodged within said cavity to establish a predetermined advance of said string enlarged section into said cavity whereby tension along said at least one string in the direction of the central opening causes said at least one string to be fixed to the frame;
- and a flexible spacer between the frame and the string enlarged section, the flexible spacer being made of a material exhibiting a recoverable stress-strain relation throughout the range of string tensions produced during operation of the racket, the range of string tensions applying compressive strains to the flexible spacer to enable a substantial part of the energy produced by the compressive string tensions to be stored by the flexible spacer, the flexible spacer returning much of the stored energy to the string.
3 more elements
A sports racket comprising:
- (a) a frame with a handle;
- (b) a throat connected to the handle;
- (c) a head connected to the throat, said head defining a central opening to be spanned by strings, said head having a means for securing strings to the frame;
- (d) a plurality of transversal strings running essentially parallel to each other and secured to the frame;
- (e) a plurality of longitudinal strings secured to the frame and running essentially orthogonal to, and in contact with, the transversal strings to form a substantially planar string network within the central opening, each contact of said transversal strings with said longitudinal strings being herein referred to as a string crossing;
- (f) at least one string crossing with at least one of the longitudinal strings involved in the string crossing having first surface indentation positioned at the string crossing and localized in extent to said string crossing;
- the transversal string involved in the string crossing having a second surface indentation positioned at the location of the string crossing and localized in extent to said string crossing, the first surface indentation matching and interlocking with the second surface indentation at approximately a 90 degree angle to produce a common contact surface having a lateral portion thereof tilted away from the midplane plane of the substantially planar string network so as to support stresses leading to lateral forces that oppose the movement of the longitudinal string relative to the transversal string;
- g) at least one string selected from the group consisting of the longitudinal strings and the transversal strings, all of said strings having first and second free-ends, said selected string having a string enlarged section at said first free-end;
- and
- h) at least one means for securing said strings to the frame is a first fixing means having:
- a main body attached to the frame, the main body extending through the thickness of the frame and having a first cavity extending the length of the main body to produce a first opening facing the planar string network and a second opening diametrically opposed to the first opening, said first cavity enabling said at least one string to be threaded through the main body by passing the second free-end through the second opening, through the first cavity, and through the first opening, the first cavity receiving the string enlarged section when the string enlarged section is within the first cavity through the second opening, the first cavity obstructing the string enlarged section from further inward movement into the first cavity beyond a predetermined advancement of the string enlarged section to the first cavity.
8 more elements
A sports racket comprising:
- a) a frame with a handle;
- b) a throat connected to the handle;
- c) a head connected to the throat, said head defining a central opening to be spanned by strings, said head having a means for securing strings to the frame;
- d) a plurality of transversal strings running essentially parallel to each other and secured to the frame;
- e) a plurality of longitudinal strings secured to the frame and running essentially orthogonal to, and in contact with, the transversal strings to form a substantially planar string network within the central opening, each contact of said transversal strings with said longitudinal strings being herein referred to as a string crossing;
- f) at least one string crossing with at least one of the longitudinal strings involved in the string crossing having a first surface indentation positioned at the string crossing and localized in extent to said string crossing;
- the transversal string involved in the string crossing having a second surface indentation positioned at the location of the string crossing and localized in extent to said string crossing, the firs surface indentation matching and interlocking with the second surface indentation at approximately a 90 degree angle to produce a common contact surface having a lateral portion thereof tilted away from the mid-plane of the substantially planar string network so as to support stresses leading to lateral forces that oppose the movement of the longitudinal string relative to the transversal string;
- g) at least one string selected from the group consisting of the longitudinal strings and the transversal strings, each of said strings having a free-end;
- and
- h) said for securing strings to the frame having;
- an enclosure body fixedly attached to the frame, a string clamping member, and a pressing means, wherein the enclosure body extends through the thickness of the frame and has a second cavity penetrating partially into the enclosure body to produce a main opening on the frame surface facing away from the central opening and to produce a base surface within the enclosure body, the enclosure body further having a bore connecting the base surface and the frame surface facing the central opening to allow the free-end of said at least one string to be received within the enclosure body, the second cavity main opening accommodating the pressing means, wherein the pressing means has a wedge shaped bore extending the entire width of the pressing means, the wedge shaped bore having said at least one string within the pressing means, the wedge shaped bore receiving said string clamping member, wherein the string clamping member has a wedge shaped outer surface with a wide end and inner passage-way for receiving said at least one string within the string clamping member;
- wherein said at least one string is received, in order, in the enclosure body, in the string clamping member, and in the pressing means, wherein the string clamping member is lodged against the enclosure body as the string clamping member and said at least one string are received in the second cavity, the string clamping member contracting the passage-way in response to compressive force on the wedge shaped outer surface, the pressing means being received in the enclosure body and over the string clamping member to engage the wedge shaped bore compressively with the wedge shaped outer surface of the string clamping member, a locking means for the pressing means to block the string clamping member within the pressing means in response to the compressive force string clamping member contraction against said at least one string.
9 more elements
Dependencies are inferred from the claim text.