Solenoid drive for a starter for an internal combustion engine

A solenoid drive for a starter, comprising:

• a ferromagnetic housing having a coil receiving chamber axially limited by a first face side wall and an opposing second face side wall;
• a cylindrical coil arrangement having at least one electric coil, the coil arrangement being arranged in the coil receiving chamber and coaxially surrounding a cylindrical coil interior space;
• a ferromagnetic plunger stop having a central region projecting axially in the coil interior space;
• a ferromagnetic plunger arranged at the housing opposing the plunger stop, the plunger projecting axially into the coil interior space and being arranged so as to be adjustable axially bi-directionally relative to the housing between an active position, which is proximal with respect to the central region, and a passive position, which is distal with respect to the central region;
• and
• a ferromagnetic bypass device extending in a circumferential direction and arranged coaxially with respect to the coil arrangement and radially within the at least one electric coil;
• wherein the bypass device is spaced apart axially from the first and second face side walls;
• wherein in the passive position, the plunger projects axially into the bypass device such that an axial overlap between the plunger and the bypass device is defined;
• and
• wherein the central region of the plunger stop has an axial distance from the bypass device.

A solenoid drive for a starter, comprising:

• a ferromagnetic housing having a coil receiving chamber axially limited by a first face side wall and an opposing second face side wall;
• a cylindrical coil arrangement having at least one electric coil, the coil arrangement being arranged in the coil receiving chamber and coaxially surrounding a cylindrical coil interior space;
• a ferromagnetic plunger stop having a central region projecting axially in the coil interior space;
• a ferromagnetic plunger arranged at the housing opposing the plunger stop, the plunger projecting axially into the coil interior space and being arranged so as to be adjustable axially bi-directionally relative to the housing between an active position, which is proximal with respect to the central region, and a passive position, which is distal with respect to the central region;
• and
• a ferromagnetic bypass device extending in a circumferential direction and arranged coaxially with respect to the coil arrangement and radially within the at least one electric coil;
• wherein the bypass device is spaced apart axially from the first and second face side walls;
• wherein in the passive position, the plunger projects axially into the bypass device such that an axial overlap between the plunger and the bypass device is defined;
• and
• wherein one of:
• the axial overlap is less than 50% of an axial height of the bypass device;
• the axial overlap is less than three times of a radial wall thickness of the bypass device;
• or
• the axial overlap is less than 5 mm plus half of a radial wall thickness of the bypass device.