Knock type writing tool

A knock type writing tool comprising:

• a writing body having a pen tip at a front end thereof, a thermochromic ink in an inside thereof, and an air hole at a rear end thereof, the air hole communicating with a space in which the thermochromic ink is contained,
• a shaft cylinder configured to contain the writing body in such a manner that the writing body is movable in a front and rear direction with respect to the shaft cylinder,
• a knock member provided on an outer surface of the shaft cylinder in such a manner that the knock member is movable in a front and rear direction with respect to the shaft cylinder,
• a projection and retraction rotating member configured to move in a front and rear direction to cause the pen tip to project from or retract within a front end of the shaft cylinder and configured to cause the writing body to rotate, every time the knock member is moved forward, and
• a cam part provided in the shaft cylinder, the cam part being able to engage or disengage with the projection and retraction rotating member depending on a position of the knock member,
• wherein
• a plurality of protrusion parts, each of which is protruded forward, are provided at a front portion of the projection and retraction rotating member, the plurality of protrusion parts being arranged circumferentially apart from each other,
• a rear end of the writing body is provided with a plurality of abutment parts, on which respective front ends of the plurality of protrusion parts are to abut, and with a plurality of projection pieces, each of which is projected more rearward than the plurality of abutment parts,
• the plurality of projection pieces are respectively inserted in a plurality of gaps between the plurality of protrusion parts, and
• a portion of each of the plurality of gaps is left behind each of the plurality of projection pieces.

A knock type writing tool comprising:

• a writing body having a pen tip at a front end thereof, a thermochromic ink in an inside thereof, and an air hole at a rear end thereof, the air hole communicating with a space in which the thermochromic ink is contained,
• a shaft cylinder configured to contain the writing body in such a manner that the writing body is movable in a front and rear direction with respect to the shaft cylinder,
• a knock member provided on an outer surface of the shaft cylinder in such a manner that the knock member is movable in a front and rear direction with respect to the shaft cylinder,
• a projection and retraction rotating member configured to move in a front and rear direction to cause the pen tip to project from or retract within a front end of the shaft cylinder and configured to cause the writing body to rotate, every time the knock member is moved forward, and
• a cam part provided in the shaft cylinder, the cam part being able to engage or disengage with the projection and retraction rotating member depending on a position of the knock member,
• wherein
• a plurality of protrusion parts, each of which is protruded forward, are provided at a front portion of the projection and retraction rotating member,
• a rear end of the writing body is provided with a flexible member which is elastically deformable,
• the flexible member is provided with a connection air hole configured to communicate with the air hole, the connection air hole being opened at a rear end or a lateral surface of the flexible member, and
• the plurality of protrusion parts and the flexible member are configured to circumferentially engage with each other when the plurality of protrusion parts cause the flexible member to elastically deform and sink in an inside of the flexible member in such a manner that the writing body rotates in conjunction with a rotation of the projection and retraction rotating member.