Camshaft adjuster with an electrical drive

Abstract

The invention relates to a device for releasably connecting and adjusting the positions between a crankshaft and a cam shaft of an internal combustion engine, which includes a setting gear ( 1 ) configured as a three-shaft gear, which has a drive shaft ( 4 ) connected to the crankshaft, an output shaft ( 5 ) connected to the camshaft, and an adjusting shaft connected to an electric adjusting motor ( 2 ). A stationary transmission ratio i o , which has a base or emergency running position, is present between the drive and output shafts when the adjusting shaft ( 6 ) is idle, the magnitude of the gear transmission ratio determining the gear type (positive or negative) and the direction of adjustment of the camshaft ( 3 ). Functional safety of the device is improved due to the fact that the base or emergency running position of the camshaft ( 3 ) can be reached and maintained in case of an outage or failure of the adjusting motor ( 2 ) and/or the control thereof be a slow-down or arresting of the adjusting shaft ( 6 ), simultaneous rotation of the drive shaft ( 4 ), and an appropriate gear transmission ratio.

1 . A device for releasably connecting and adjusting a camshaft ( 3 ,  3 ′) and a crankshaft of an internal combustion engine, comprising an adjusting gear ( 1 ,  1 ′) formed as a three shaft transmission, which has a drive shaft ( 4 ,  4 ′) connected with the crankshaft, an output shaft ( 5 ,  5 ′) connected with the camshaft, and an adjusting shaft ( 6 ,  6 ′) connected with an electric adjusting motor ( 2 ,  2 ′), a gear transmission ratio i o  is defined between the drive shaft and the output shaft ( 4 ,  4 ′;  5 ,  5 ′) when the adjusting shaft ( 6 ,  6 ′) is at rest, and a magnitude of the gear transmission ratio is determined by a gear type and a direction of setting of camshaft ( 3 ,  3 ′), which has a base or emergency running position, wherein upon a failure of the adjusting motor ( 2 ,  2 ′) or a controlling system, the base or emergency running position of camshaft ( 3 ,  3 ′) can be reached and maintained by one of braking or setting the adjusting shaft ( 6 ,  6 ′), and rotation of drive shaft ( 4 ,  4 ′), as well as the gear transmission ratio i o .  
   
   
       2 . The device according to  claim 1 , for a late adjustment of camshaft ( 3 ,  3 ′) a minus gear with i o <0 or a plus gear with i o >1 is provided, and for an early adjustment of camshaft ( 3 ,  3 ′) a plus gear with 0<i o <1 is provided.  
   
   
       3 . The device according to  claim 2 , wherein the adjusting motor ( 2 ) includes a rotor ( 8 ) and a stator fixedly connected to a cylinder head, the rotor ( 8 ) includes a permanent magnet, and for a power free setting of the adjusting shaft ( 6 ) a holding torque of the adjusting motor is utilized.  
   
   
       4 . An adjustment device for an engine including a camshaft and a crankshaft, the device comprising: 
 an adjusting shaft;    a drive shaft for connection to the crankshaft;    an output shaft for connection to the camshaft; and    a gear transmission, connected to the output shaft, the drive shaft and the adjusting shaft, the gear transmission configured to rotate the output shaft and the adjusting shaft at a predetermined rate in response to a given input from the drive shaft, wherein braking the adjusting shaft results in at least one of increasing and decreasing a rotation speed of the output shaft relative to a rotation speed of the drive shaft.    
   
   
       5 . The adjustment device of  claim 4 , further comprising an electric motor connected to the adjusting shaft for braking the adjusting shaft.  
   
   
       6 . The adjustment device of  claim 4 , further comprising a mechanical brake connected to the adjusting shaft for braking the adjusting shaft.  
   
   
       7 . The adjustment device of  claim 4 , wherein the gear transmission includes a gear transmission ratio i o  associated with the adjusting shaft which is greater than 1, wherein when the adjustment shaft is braked, the output shaft rotational speed is increased relative to the drive shaft rotational speed, whereby the camshaft rotational speed is increased relative to the crankshaft rotational speed.  
   
   
       8 . The adjustment device of  claim 4 , wherein the gear transmission includes a gear transmission ration i o  which is less than 1, wherein when the adjustment shaft is braked, the output shaft rotational speed is decreased relative to the drive shaft rotational speed, whereby the camshaft rotational speed is decreased relative to the crankshaft rotational speed.  
   
   
       9 . An engine comprising: 
 a camshaft;    a crankshaft;    an adjusting shaft;    a drive shaft connected to the crankshaft;    an output shaft connected to the camshaft; and    a gear transmission, connected to the output shaft, the drive shaft and the adjusting shaft, the gear transmission configured to rotate the output shaft and the adjusting shaft at a predetermined rate in response to a given input from the drive shaft, wherein braking the adjusting shaft results in at least one of increasing and decreasing a rotation speed of the output shaft relative to a rotation speed of the drive shaft.    
   
   
       10 . The engine of  claim 9 , further comprising an electric motor connected to the adjusting shaft for braking the adjusting shaft.  
   
   
       11 . The engine of  claim 9 , further comprising a mechanical brake connected to the adjusting shaft for braking the adjusting shaft.  
   
   
       12 . The engine of  claim 9 , wherein the gear transmission includes a gear transmission ratio i o  associated with the adjusting shaft which is greater than 1, wherein when the adjustment shaft is braked, the output shaft rotational speed is increased relative to the drive shaft rotational speed, whereby the camshaft rotational speed is increased relative to the crankshaft rotational speed.  
   
   
       13 . The engine of  claim 9 , wherein the gear transmission includes a gear transmission ration i o  which is less than 1, wherein when the adjustment shaft is braked, the output shaft rotational speed is decreased relative to the drive shaft rotational speed, whereby the camshaft rotational speed is decreased relative to the crankshaft rotational speed.