Thermal disconnect

A device for moving a first shaft relative to a second shaft between an engaged position wherein cooperating structures carried by the first and second shafts are engaged so that the shafts rotate together and a disengaged position wherein the cooperating structures carried by the first and second shafts are disengaged from one another, comprising:

• a disconnect plunger having an engaging member engageable with a first portion of the first shaft;
• first means for urging the disconnect plunger toward the first shaft whereby the engaging member engages the first portion of the first shaft and causes the first shaft to move to the disengaged position;
• a solenoid having a housing and a solenoid plunger extending outwardly from the housing, the solenoid capable of assuming two states in which the solenoid plunger is disposed in different positions relative to the housing;
• second means in contact with the solenoid housing for urging the solenoid plunger away from the disconnect plunger;
• and
• third means effective at temperatures lower than a certain temperature for resisting the urging of the second means so that the solenoid plunger contacts the disconnect plunger when the solenoid assumes one of the states to thereby prevent movement of the disconnect plunger into engagement with the first shaft and effective at temperatures higher than the certain temperature to allow the solenoid plunger to move under the influence of the second urging means out of contact with the disconnect plunger whereby the disconnect plunger moves into engagement with the first shaft under the influence of the first urging means.

A device for moving a first shaft relative to a second shaft between an engaged position wherein cooperating structures carried by the first and second shafts are engaged so that the shafts rotate together and a disengaged position wherein the cooperating structures carried by the first and second shafts are disengaged from one another, comprising:

• a disconnect plunger having an engaging member engageable with a first portion of the first shaft;
• first means for urging the disconnect plunger toward the first shaft whereby the engaging member engages the first portion of the first shaft and causes the first shaft to move to the disengaged position;
• a solenoid having a housing, an armature and windings disposed in the housing and a solenoid plunger coupled to the armature, the solenoid being operable in either of deenergized and energized states in which the solenoid plunger is disposed in first and second positions relative to the housing, respectively;
• a second spring disposed in the housing on a first side of the armature for urging the solenoid plunger away from the disconnect plunger;
• a third spring disposed in the housing on a second side of the armature;
• and
• thermally responsive means effective at temperatures lower than a certain temperature for supporting the third spring such that the third spring resists the urging of the second spring whereby the solenoid plunger extends out of the housing into engagement with the disconnect plunger to prevent the disconnect plunger from contacting the first shaft and effective at temperatures higher than the certain temperature for removing the support of the third spring whereby the solenoid plunger moves under the influence of the second springs out of contact with the disconnect plunger such that the disconnect plunger moves into engagement with the first shaft under the influence of the first spring.