Shift actuator for a transmission

Abstract

A shift actuator for a transmission, which actuates, in a direction of shift, a shift lever for operating a synchronizing device of the transmission, the shift actuator comprising a first electromagnetic solenoid and a second electromagnetic solenoid for actuating an operation member coupled to the shift lever in the directions opposite to each other. Each of the first electromagnetic solenoid and the second electromagnetic solenoid comprises a casing, a fixed iron core disposed in the casing, a moving iron core arranged to be allowed to approach, and separate away from, the fixed iron core, an operation rod mounted on the moving iron core to engage with the operation member, and an electromagnetic coil arranged between the casing and the fixed iron core as well as the moving iron core.

What we claim is:  
     
         1 . A shift actuator for a transmission, which actuates, in a direction of shift, a shift lever for operating a synchronizing device of the transmission, the shift actuator comprising: 
 a first electromagnetic solenoid and a second electromagnetic solenoid for actuating an operation member coupled to said shift lever in the directions opposite to each other;    each of said first electromagnetic solenoid and said second electromagnetic solenoid comprising a casing, a fixed iron core disposed in said casing, a moving iron core arranged to be allowed to approach, and separate away from, said fixed iron core, an operation rod mounted on said moving iron core to engage with said operation member, and an electromagnetic coil arranged between said casing and said fixed iron core as well as said moving iron core.    
     
     
         2 . A shift actuator for a transmission according to  claim 1 , wherein a stepped protuberance is formed on either one of the opposing surfaces of said fixed iron core and of said moving iron core, a stepped recess is formed in the other surface to correspond to said stepped protuberance, and a position at which an edge of said protuberance and an edge of said recess become closest to each other is so constituted as to correspond to the synchronizing position of said synchronizing device.  
     
     
         3 . A shift actuator for a transmission, which actuates, in a direction of shift, a shift lever for operating a synchronizing device of the transmission, the shift actuator comprising: 
 a first electromagnetic solenoid and a second electromagnetic solenoid for actuating an operation member coupled to said shift lever in the directions opposite to each other;    each of said first electromagnetic solenoid and said second electromagnetic solenoid comprising an electromagnetic coil, a fixed iron core disposed in said electromagnetic coil, a moving iron core arranged to be allowed to approach, and separate away from, said fixed iron core, a fixed yoke having an inner peripheral surface opposing an outer peripheral surface of said moving iron core, and an operation rod mounted on said moving iron core to engage with said operation member; and    the opposing areas of said moving iron core and said fixed yoke being so constituted as to decrease, at a position where said fixed iron core ceases to attract said moving iron core.    
     
     
         4 . A shift actuator for a transmission according to  claim 3 , wherein a stepped protuberance is formed on either one of the opposing surfaces of said fixed iron core and of said moving iron core, a stepped recess is formed in the other surface to correspond to said stepped protuberance, and a position at which an edge of said protuberance and an edge of said recess become closest to each other is so constituted as to correspond to the synchronizing position of said synchronizing device.  
     
     
         5 . A shift actuator for a transmission, having a first electromagnetic solenoid and a second electromagnetic solenoid for actuating, in the directions opposite to each other, an operation member coupled to the shift lever to operate a synchronizing device of the transmission, wherein 
 each of said first electromagnetic solenoid and said second electromagnetic solenoid comprises an electromagnetic coil, a fixed iron core excited by said electromagnetic coil, a first moving iron core arranged to be allowed to approach, and separate away from, said fixed iron core, a second moving iron core fitted to an outer peripheral surface of said first moving iron core so as to slide therealong, and an operation rod mounted on said first moving iron core to engage with said operation member;    said fixed iron core having a first attraction portion for attracting said first moving iron core and a second attraction portion for attracting said second moving iron core, and said first moving iron core being provided with a limiting means for limiting said second moving iron core from moving toward the side of said fixed iron core, and    said second moving iron core and said first moving iron core being so constituted as to move together, by the action of said limiting means, until said second moving iron core comes in contact with said second attraction portion, then, said first moving iron core alone moving toward said first attraction portion after said second moving iron core has come in contact with said second attraction portion, and a position at which said second moving iron core comes in contact with said second attraction portion being so set as to correspond to a position just after a synchronizing position of said synchronizing device.