US2003140875A1PendingUtilityA1
Method for estimating the position and speed of an actuator body in an electromagnetic actuator for controlling the valve of an engine
Assignee: MAGNETI MARELLI POWERTRAIN SPAPriority: Dec 14, 2001Filed: Dec 11, 2002Published: Jul 31, 2003
Est. expiryDec 14, 2021(expired)· nominal 20-yr term from priority
F01L 9/20F01L 2009/2109F01L 2009/2136F02D 2041/2034F02D 41/20F02D 2200/063H01F 7/1844F01L 2800/00F02D 2041/001F02D 13/0253F02D 2041/2079F02D 2041/2055Y02T10/12F02D 2041/2058
32
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Claims
Abstract
Method for estimating the position and the speed of an actuator body in an electromagnetic actuator for controlling a valve of an engine, according to which, starting from a known value for the position and a first moment, a value is calculated at the first moment of the magnetic flux passing through a magnetic circuit constituted by an electromagnet and by the actuator body, the value for the speed at the first moment is estimated as a function of the magnetic flux and the position at the first moment, and the value is calculated at a second moment following the first moment and separated from said first moment by an interval of time determined by adding to the value of the position at the first moment the product of the speed at the first moment for the interval of time.
Claims
exact text as granted — not AI-modified1 . Method for estimating the position (x) and the speed (v) of an actuator body ( 4 ) in an electromagnetic actuator ( 1 ) for controlling a valve ( 2 ) of an engine; the actuator body ( 4 ) being made at least partly of ferromagnetic material and being displaced towards at least one electromagnet ( 8 ) through the effect of the force of magnetic attraction generated by said electromagnet ( 8 ); the method being characterised by the fact that starting from a known value of the position (x) and a first moment (T1), a value is calculated at the first moment (T1) of the magnetic flux (p) passing through a magnetic circuit ( 18 ) constituted by the electromagnet ( 8 ) and by the actuator body ( 4 ), the value of the speed (v) at the first moment (T1) is estimated as a function of the magnetic flux (φ) and the position (x) at the first moment (T1), and the value is calculated at a second moment (T2) following the first moment (T1) and separated from said first moment (T1) by an interval of time (dt) determined by adding to the value of the position (x) at the first moment (T1) the product of the speed (v) at the first moment (T1) for the interval of time (dt).
2 . Method according to claim 1 , in which said electromagnet ( 8 ) defines, together with said actuator body ( 4 ), a magnetic circuit ( 18 ) influenced by a magnetic flux (φ) produced by a coil ( 17 ) through which an electric current (i) passes; said magnetic circuit ( 18 ) having a total reluctance (R), which is assumed to be composed of the sum of a first reluctance (R 0 ) arising from an air gap ( 19 ) in the magnetic circuit ( 18 ) and a second reluctance (R fe ) arising from the part of the magnetic circuit ( 18 ) made of ferromagnetic material ( 4 , 16 ); the first reluctance (R 0 ) depending on the structural properties of the magnetic circuit ( 18 ) and on the value of the position (x), while the second reluctance (R fe ) depending on the structural properties of the magnetic circuit ( 18 ) and on the value of the magnetic flux (φ) passing through the magnetic circuit ( 18 ).
3 . Method according to claim 2 , in which the value for said first reluctance (R 0 ) and the value for said position (x) are connected by the following equation:
R 0 ( x ( t ))= K 1 [1 −e −k 2 x(t) +k 3 ·x ( t )]+ K 0
in which R 0 is said first reluctance (R 0 ), x(t) is said position (x) and K 0 , K 1 , K 2 , K 3 are four constants.
4 . Method according to claim 2 , in which the relationship between the speed (v), the magnetic flux (φ) and the position (x) is supplied by the following equation:
i
(
t
)
t
=
∂
R
0
(
x
(
t
)
)
∂
x
·
x
(
t
)
t
·
ϕ
(
t
)
+
R
0
(
x
(
t
)
)
·
ϕ
(
t
)
t
+
∂
H
fe
(
ϕ
(
t
)
)
∂
ϕ
·
ϕ
(
t
)
t
x
(
t
)
t
=
i
(
t
)
t
-
R
0
(
x
(
t
)
)
·
ϕ
(
t
)
t
-
∂
H
fe
(
ϕ
(
t
)
)
∂
ϕ
·
ϕ
(
t
)
t
∂
R
0
(
x
(
t
)
)
∂
x
·
ϕ
(
t
)
in which i is the electric current (i) circulating within the coil ( 17 ), R 0 is said first reluctance (R 0 ), x is the position (x) of the actuator body ( 4 ), φ is the magnetic flux (φ) and H fe is the quantity of ampere-turns acted on by the iron part ( 4 , 16 ) of the magnetic circuit ( 18 ).
5 . Method according to claim 1 , in which the value of the magnetic flux (φ) is estimated by measuring the value assumed from some electric parameters (i, v; va) of an electric circuit ( 17 ; 22 ) coupled to the magnetic circuit ( 18 ), calculating the time derivative of the magnetic flux (φ) as a linear combination of the values of the electrical parameters (i, v; va), and integrating in time the derivative of the magnetic flux (φ).
6 . Method according to claim 5 , in which the current (i) circulating through a coil ( 17 ) of the electromagnet ( 8 ) and the voltage (v) applied to the terminals of said coil ( 17 ) are measured; the time derivative of the magnetic flux (φ) and the magnetic flux (φ) itself being calculated by applying the following formulae:
ϕ
(
t
)
t
=
v
(
t
)
-
RES
·
i
(
t
)
ϕ
(
T
)
=
∫
0
T
(
v
(
t
)
-
RES
·
i
(
t
)
)
t
+
ϕ
(
0
)
in which φ is the magnetic flux (φ), v is the voltage (v) applied to the terminals of the coil ( 17 ), RES is the resistance of the coil ( 17 ) and i is the current (i) circulating through the coil ( 17 ).
7 . Method according to claim 6 , in which the voltage (v aux ) at the terminals of an auxiliary turn ( 22 ) coupled to the magnetic circuit ( 18 ) and concatenating the magnetic flux (φ) is measured; the auxiliary turn ( 22 ) being substantially open electrically; and the time derivative of the magnetic flux (φ) and the magnetic flux (φ) itself being calculated by applying the following formulae:
ϕ
(
t
)
t
=
v
aus
(
t
)
ϕ
(
T
)
=
∫
0
T
v
aus
(
t
)
t
+
ϕ
(
0
)
in which φ is the magnetic flux (φ) and v aux is the voltage (v aux ) present at the terminals of the auxiliary turn ( 22 ).Join the waitlist — get patent alerts
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