Eddy current retarder equipment
Eddy current retarder equipment ( 1 ) able to be carried on board a vehicle, includes: a stator assembly ( 2 ), including inductor windings ( 23 ) forming a circuit ( 4 ), a rotor assembly ( 3 ) designed to be mounted on a transmission shaft of the vehicle, including an armature ( 31 ) facing the inductor windings ( 23 ), control elements ( 6 ) for establishing a linear setpoint (β), excitation elements ( 7 ) for exciting the inductor circuit ( 4 ) from an electric power source ( 5 ) of the vehicle as a function of the setpoint (β), a speed sensor ( 9 ) for supplying information relating to the rotational speed (Ω) of the rotor assembly ( 3 ), a sensor ( 10 ) of the strength of current supplied to the inductor circuit ( 4 ), processing elements ( 8 ) for estimating, at a given moment (t), the retarding torque supplied by the equipment ( 1 ).
1. Eddy current retarder equipment ( 1 ) capable of being carried on board a vehicle, comprising:
a stator assembly ( 2 ),
a rotor assembly ( 3 ) capable of being mounted on a transmission shaft of the vehicle,
one of said stator assembly ( 2 ) and rotor assembly ( 3 ) comprising inductor windings ( 23 ) forming an inductor circuit ( 4 ) and the other of said stator assembly ( 2 ) and rotor assembly ( 3 ) comprising an armature ( 31 ) facing the inductor windings ( 23 ),
the equipment ( 1 ) further comprising:
control means ( 6 ) for establishing a linear setting (β),
excitation means ( 7 ) for exciting the inductor circuit ( 4 ) from an electric power source ( 5 ) of the vehicle as a function of the setting (β),
a speed sensor ( 9 ) for providing information relating to the rotational speed (Ω) of the rotor assembly ( 3 ),
a sensor ( 10 ) of the strength of current supplying the inductor circuit ( 4 ),
processing means ( 8 ) for estimating at a given time (t) the retarding torque provided by the equipment ( 1 ),
the processing means ( 8 ) comprising a unit ( 13 ) for calculating temperature capable of evaluating the temperature (T R ) of the armature ( 31 ), as a function in particular of the rotational speed (Ω) of the rotor assembly ( 3 ) and of the linear setting (β),
wherein the processing means further comprise:
a torque calculation unit ( 14 ) for calculating a torque (T cold ) referred to as cold, as a function in particular of the current (I measured ) in the inductor circuit ( 4 ) and the rotational speed (Ω) of the rotor assembly ( 3 ), characteristic of an operation of the equipment without the influence of temperature;
a unit ( 15 ) for calculating a reduction factor (R), as a function in particular of the rotational speed (Ω) of the rotor assembly ( 3 ) and the temperature (T R ) of the armature ( 31 ), characteristic of the influence of temperature on the operation of the equipment;
a unit ( 16 ) for calculating a torque (T hot ) referred to as hot, as a function in particular of the product of the cold torque (T cold ) and the reduction factor (R), characteristic of the actual retarding torque provided by the equipment.
2. Equipment ( 1 ) according to claim 1 , in which the control means ( 6 ) comprise a manual or foot control device capable of adopting an infinity of positions between two extreme positions.
3. Equipment ( 1 ) according to claim 2 , in which the control means ( 6 ) comprise an electronic control unit.
4. Equipment ( 1 ) according to claim 2 , in which the armature ( 31 ) is carried by the rotor assembly ( 3 ) and the inductor windings ( 23 ) are carried by the stator assembly ( 2 ).
5. Equipment ( 1 ) according to claim 2 , in which the temperature (T R ) of the armature ( 31 ) is calculated by a successive approach, the value of the temperature (T R ) of the armature ( 31 ) at a given time depending in particular on the value of the temperature (T R ) of the armature ( 31 ) calculated at the previous time (t−1), the setting (β) and the rotational speed (Ω) of the stator assembly ( 2 ) at the given time (t) or at the previous time (t−1).
6. Equipment ( 1 ) according to claim 5 , in which the unit ( 13 ) for calculating the temperature (T R ) of the armature ( 31 ) is arranged in order to calculate the temperature (T R ) of the armature according to the following formula:
T R ( t )= T R ( t− 1)+α× K p ×[b×Ω+c×T R ( t− 1)+ d×Ω×T R ( t− 1)+ e×T R ( t− 1) 2 ]
in which:
T R (t) is the temperature of the armature at the given time t,
T R (t−1) is the temperature of the armature at the previous time t−1,
Ω is the rotational speed of the rotor assembly at the given time or at the previous time,
b
=
b
1
+
16
×
b
2
×
β
4
+
b
var
16
×
β
-
0.01
,
c
=
c
1
+
4
×
c
2
×
β
,
d
=
d
1
+
4
×
d
2
×
β
,
e
=
e
1
+
4
×
e
2
×
β
,
K
P
=
1
+
(
K
P
0
-
1
)
×
Ω
3000
,
a, b 1 , b 2 , b var , c 1 , c 2 , d 1 , d 2 , e 1 , e 2 and K P0 are constant coefficients,
β denotes the linear supply setting, expressed as a percentage, applied to the excitation means.
7. Equipment ( 1 ) according to claim 2 , in which the excitation means ( 7 ) comprise a power regulator connected on the one hand to the power source ( 5 ) and on the other hand to the inductor circuit ( 4 ).
8. Equipment ( 1 ) according to claim 1 , in which the control means ( 6 ) comprise an electronic control unit.
9. Equipment ( 1 ) according to claim 8 , in which the armature ( 31 ) is carried by the rotor assembly ( 3 ) and the inductor windings ( 23 ) are carried by the stator assembly ( 2 ).
10. Equipment ( 1 ) according to claim 1 , in which the armature ( 31 ) is carried by the rotor assembly ( 3 ) and the inductor windings ( 23 ) are carried by the stator assembly ( 2 ).
11. Equipment ( 1 ) according to claim 1 , in which the temperature (T R ) of the armature ( 31 ) is calculated by a successive approach, the value of the temperature (T R ) of the armature ( 31 ) at a given time depending in particular on the value of the temperature (T R ) of the armature ( 31 ) calculated at the previous time (t−1), the setting (β) and the rotational speed (Ω) of the stator assembly ( 2 ) at the given time (t) or at the previous time (t−1).
12. Equipment ( 1 ) according to claim 11 , in which the unit ( 13 ) for calculating the temperature (T R ) of the armature ( 31 ) is arranged in order to calculate the temperature (T R ) of the armature according to the following formula:
T R ( t )= T R ( t− 1)+α× K p ×[b×Ω+c×T R ( t− 1)+ d×ΩT R ( t− 1)+ e×T R ( t− 1) 2 ]
in which:
T R (t) is the temperature of the armature at the given time t,
T R (t−1) is the temperature of the armature at the previous time t−1,
Ω is the rotational speed of the rotor assembly at the given time or at the previous time,
b
=
b
1
+
16
×
b
2
×
β
4
+
b
var
16
×
β
-
0.01
,
c
=
c
1
+
4
×
c
2
×
β
,
d
=
d
1
+
4
×
d
2
×
β
,
e
=
e
1
+
4
×
e
2
×
β
,
K
P
=
1
+
(
K
P
0
-
1
)
×
Ω
3000
,
a, b 1 , b 2 , b var , c 1 , c 2 , d 1 , d 2 , e 1 , e 2 and K P0 are constant coefficients,
β denotes the linear supply setting, expressed as a percentage, applied to the excitation means.
13. Equipment ( 1 ) according to claim 12 , in which the unit ( 15 ) for calculating the reduction factor (R) is arranged in order to calculate the reduction factor (R) at a given time (t) according to the following formula:
R=j ×ln(Ω)+ k
in which:
j=j 1 ×T R ( t ) 4 +j 2 ×T R ( t ) 3 +j 3 ×T R ( t ) 2 +j 4 ×T R ( t )+ j 5 ,
k=k 1 ×T R ( t ) 4 +k 2 ×T R ( t ) 3 +k 3 ×T R ( t ) 2 +k 4 ×T R ( t )+ k 5 ,
T R (t) is the temperature of the armature calculated at the given time t,
Ω is the rotational speed of the rotor assembly at the given time t or at the previous time t−1,
j 1 to j 5 and k 1 to k 5 are constant coefficients.
14. Equipment ( 1 ) according to claim 11 , in which the unit ( 15 ) for calculating the reduction factor (R) is arranged in order to calculate the reduction factor (R) at a given time (t) according to the following formula:
R=j ×ln(Ω)+ k
in which:
j=j 1 ×T R ( t ) 4 +j 2 ×T R ( t ) 3 +j 3 ×T R ( t ) 2 +j 4 ×T R ( t )+ j 5 ,
k=k 1 ×T R ( t ) 4 +k 2 ×T R ( t ) 3 +k 3 ×T R ( t ) 2 +k 4 ×T R ( t )+ k 5 ,
T R (t) is the temperature of the armature calculated at the given time t,
Ω is the rotational speed of the rotor assembly at the given time t or at the previous time t−1,
j 1 to j 5 and k 1 to k 5 are constant coefficients.
15. Equipment ( 1 ) according to claim 14 , in which the unit ( 14 ) for calculating the cold torque is arranged in order to calculate the cold torque at a given time (t) according to the following formula:
T
cold
=
α
[
(
Ω
Ω
0
)
γ
+
(
Ω
0
Ω
)
δ
]
in which:
α=f 1 ×I pc +f 2 ,
Ω 0 =g 1 ×I pc +g 2 ,
γ=h 1 ×I pc 3 +h 2 ×I pc 2 +h 3 ×I pc +h4,
Ω is the rotational speed of the rotor assembly at the given time t or at the previous time t−1,
Where
f 1 , f 2 , g 1 , g 2 , h 1 , h 2 , h 3 are constant coefficients,
I pc is a value of the maximum strength of the current available in the inductor circuit ( 4 ) as a function of the linear supply setting (β).
16. Equipment ( 1 ) according to claim 15 , in which the unit ( 16 ) for calculating the hot torque (T hot ) is arranged in order to calculate the hot torque (T hot ) at a given time (t) according to the following formula:
T hot =T cold ×R.
17. Equipment ( 1 ) according to claim 11 , in which the unit ( 14 ) for calculating the cold torque is arranged in order to calculate the cold torque at a given time (t) according to the following formula:
T
cold
=
α
[
(
Ω
Ω
0
)
γ
+
(
Ω
0
Ω
)
δ
]
in which:
α=f 1 ×I pc +f 2 ,
Ω 0 =g 1 ×I pc +g 2 ,
γ=h 1 ×I pc 3 +h 2 ×I pc 2 +h 3 ×I pc +h4,
Ω is the rotational speed of the rotor assembly at the given time t or at the previous time t−1,
where
f 1 , f 2 , g 1 , g 2 , h 1 , h 2 , h 3 are constant coefficients,
I pc is a value of the maximum strength of the current available in the inductor circuit ( 4 ) as a function of the linear supply setting (β).
18. Equipment ( 1 ) according to claim 1 , in which the excitation means ( 7 ) comprise a power regulator connected on the one hand to the power source ( 5 ) and on the other hand to the inductor circuit ( 4 ).
19. Method for calculating, at a given time (t), an actual braking torque used by an eddy current retarder equipment ( 1 ) capable of being carried on board a vehicle according to claim 1 , comprising the following steps:
measuring the strength of the current (I measured ) in the inductor circuit ( 4 );
measuring the rotational speed (Ω) of the rotor assembly ( 3 );
evaluating the temperature of the armature, as a function in particular of the rotational speed (Ω) of the rotor assembly ( 3 ) and the linear setting (β);
calculating a torque (T cold ) referred to as cold, as a function in particular of the current (I measured ) in the inductor circuit ( 4 ) and of the rotational speed (Ω) of the rotor assembly ( 3 ), characteristic of an operation of the equipment without the influence of temperature;
calculating a reduction factor (R), as a function in particular of the rotational speed (Ω) of the rotor assembly ( 3 ) and of the temperature (T R ) of the armature ( 31 ), characteristic of the influence of temperature on the operation of the equipment;
calculating a torque (T hot ) referred to as hot as a function in particular of the product of the cold torque (T cold ) and the reduction factor (R), characteristic of the actual braking torque provided by the equipment.