Prestroke adjustment method for fuel injection valve

A prestroke adjustment method for adjusting a prestroke amount of a fuel injection valve that includes:

• a valve member having a valve body at a tip portion, the valve body being capable of seating on and separating from a valve seat;
• a movable element relatively displaceable in a valve opening/closing direction with respect to the valve member and engageable with the valve member;
• and
• a gap forming member configured to be relatively displaceable in the valve opening/closing direction with respect to the valve member and the movable element, the gap forming member forming a gap defining a prestroke between the valve member and an engagement portion of the movable element by a second portion abutting on the movable element while a first portion is positioned at a reference position of the valve member, wherein
• the gap forming member has an adjustment margin before adjustment of the prestroke amount,
• a load in a direction from the first portion toward the reference position of the valve member is applied to the gap forming member while being assembled to the valve member,
• the gap forming member is plastically deformed to reduce a relative length between the first portion and the second portion to set the prestroke amount to a target value,
• the load is applied to the gap forming member by sandwiching the gap forming member assembled to the valve member between a first jig and a second jig,
• the first jig has a contact surface on which an engagement portion of the valve member abuts and a first pressing surface on which the second portion of the gap forming member abuts,
• the contact surface forms a step having a height corresponding to the target value of the prestroke amount with respect to the first pressing surface, and
• plastic deformation of the gap forming member is performed until the first portion of the gap forming member abuts on the reference position of the valve member while the engagement portion of the valve member abuts on the contact surface of the first jig and while the second portion of the gap forming member abuts on the first pressing surface of the first jig.