WO2008070066B1

WO2008070066B1 - Control structure for electro-mechanical camshaft phase shifting device

Info

Publication number: WO2008070066B1
Application number: PCT/US2007/024822
Authority: WO
Inventors: Xiaolan Ai; Don Remboski
Original assignee: Timken Co; Xiaolan Ai; Don Remboski
Priority date: 2006-12-05
Filing date: 2007-12-04
Publication date: 2008-09-04
Also published as: US20110011359A1; WO2008070066A2; EP2089613A2; WO2008070066A3; KR20090096465A; JP2010511839A

Abstract

A camshaft phase shifting device (30) includes a coaxially arranged three-shaft gear system, having an input shaft (16), an output shaft (14), and a control shaft (34) for adjusting the phase angle between the input and output shafts (16, 14). The control structure is a torque-based control structure. The dynamic response of the gear system and thus the desired phase angle of a camshaft (12) associated with the output shaft (16) is controlled and adjusted by a controller (40) which produces a torque command based on received signals. These signals include, but are not limited to, cam shaft phase angle error signal, torque load, and/or angular position signal of the camshaft (12), and relative speed signal between the input and output shafts (16, 14). The torque command is converted by an electric machine (32) into an electro-magnetic torque exerting on the control shaft (34) of the camshaft phase shifting device (30), and includes two parts, a feed forward part to compensate for the known disturbances in system torques and a feedback part to compensate for unknown disturbances.

Claims

AMENDED CLAIMS received by the International Bureau on 09 June 2008 (09.06.2008)

1. A camshaft phase shifting device comprising: a coaxially arranged three-shaft gear system, having an input shaft, an output shaft, and a control shaft, said control shaft configured to adjust a phase angle between said input shaft and said output shaft; a controller operatively coupled to said control shaft, said controller responsive to at least one input signal to regulate a source of an applied electromagnetic torque to said control shaft to unlock the phase angle of said input shaft relative to said output shaft.

2. The camshaft phase shifting device of Claim 1 wherein said controller operates with a torque-based control structure.

3. The camshaft phase shifting device of Claim 1 wherein said controller is configured to generate a torque command to said source of applied electromagnetic torque in response to said at least one plurality of input signal.

4. The camshaft phase shifting device of Claim 1 wherein said at least one input signal is selected from a set of input signals including, but not limited to, a cam shaft phase angle error signal, a torque load signal, an angular position signal of the cam shaft, and relative speed signal between the input and output shafts.

5. The camshaft phase shifting device of Claim 1 wherein said source of applied electro-magnetic torque is an electric machine configured to exert said electro-magnetic torque on said control shaft, said electric machine regulated by a torque command from said controller.

6. The camshaft phase shifting device of Claim 5 wherein said torque command includes at least a feed-forward component to compensate for known disturbances in system torques, and at least a feedback component to compensate for unknown disturbances and to track reference input.

7. The camshaft phase shifting device of Claim 6 wherein said feedforward component of said torque command is calculated as:

Tg* = T*_*«, + ^JH^ = {l ~SS_t) -T_m + sgn(v) -f [T₀Jj 11

where

T_rq__atati_c is the torque load reflected on the control shaft based on frictionless static equilibrium condition of the phase shifting device;

T_rq_jri_cti_on is the force required to overcome the frictional torque corresponding to the current control shaft torque load;

SR₀ is the base speed ratio of the output shaft relative to the input shaft;

T_eam is the cam shaft torque load; sgn(v) represents the sign of a relative speed v between the control shaft and the input shaft; and f(Tcam) represent the magnitude of the frictional torque Taction-

8. The camshaft phase shifting device of Claim 7 wherein SRo is calculated according to:

where N denotes the number of gear teeth with its subscripts si, _S2, _PI, and _P2 representing a first sun gear coupled to the input shaft, a second sun gear coupled to the output shaft, a first planet gear engaged with the first sun gear, and a second planet gear engaged with the second sun gear, respectively; and wherein said first and second planet gears are integral with a common planet carrier coupled to said control shaft.

9. The camshaft phase shifting device of Claim 1 wherein said three-shaft gear system includes a friction self-locking mechanism configured to phase-lock said input shaft and said output shaft, said frictional self-locking mechanism transmitting torque from said input shaft to said output shaft; and wherein an application of torque to said control shaft of said frictional self-locking mechanism selectively unlocks the phase angle of said input shaft relative to said output shaft.

10. A method for altering a camshaft phase angle for a camshaft driven though a camshaft phase shifting device including coaxially aligned input, output and 12

control shafts, wherein the input shaft and the output shaft are frictionally phase- locked by said control shaft, comprising: regulating a torque applied to said control shaft, wherein an application of torque to said control shaft unlocks said input shaft phase from said output shaft phase.

11. The method of Claim 10 for altering a camshaft phase angle wherein said step of regulating said torque applied to said control shaft is responsive to at least one input signal selected from a set of input signals including, but not limited to, a cam shaft phase angle error signal, a torque load signal, an angular position signal of the cam shaft, and relative speed signal between the input and output shafts.

12. The method of Claim 10 for altering a camshaft phase angle wherein said step of regulating said torque applied to said control shaft includes controlling an electric machine configured to exert an electro-magnetic torque on said control shaft.