Toothed belt drive
Toothed belt drive having one toothed belt and at least two, preferably helically geared, toothed pulleys, wherein the toothed belt wraps the toothed pulleys over a part-region of the circumference of the latter and the teeth of the toothed belt mesh in the tooth gaps of the toothed pulleys, wherein the air gap E S or E S(mk) that relates to the nominal pitch P and results from the difference between the width es of the tooth gaps of the respective toothed pulley and the width e R of the teeth of the toothed belt is configured at the mean height of the teeth, depending on the tooth count z R of the toothed pulleys and on the tooth count z of the toothed pulleys, or on the tooth counts z k of the smaller toothed pulley and on z g of the larger toothed pulley, respectively.
1. A toothed belt drive comprising:
a toothed belt having a plurality of teeth and at least one drive side provided with a first toothed profile;
at least two toothed pulleys each having a circumference and defining tooth gaps;
said toothed pulleys each having a second toothed profile that is complementary to said first toothed profile;
said toothed belt being configured to wrap said at least two toothed pulleys over a part-region of the circumference of each of said at least two toothed pulleys;
said teeth of said toothed belt being configured to mesh in said tooth gaps of said at least two toothed pulleys;
wherein an air gap (E S ) that relates to a nominal pitch (P) and results from a difference between a width (e S ) of the tooth gaps of the respective one of said at least two toothed pulleys and a width (e R ) of said teeth of said toothed belt at a mean height of said teeth, depending on a tooth count (z R ) of said toothed belt and on a tooth count (z) of said respective one of said at least two toothed pulleys, is configured such that
E
S
=
e
S
-
e
R
=
[
C
S
+
0.004
·
z
z
R
-
z
]
·
P
wherein (C S ) is predefined as a constant for a standard backlash in the case of toothed belt drives in a range of
0.06≤C S ≤0.08.
2. The toothed belt drive of claim 1 , wherein one of said at least two toothed pulleys has a pitch circle diameter of (d)≤45 mm.
3. The toothed belt drive of claim 1 , wherein one of said at least two toothed pulleys has a tooth count between 20 and 60.
4. The toothed belt drive of claim 1 , wherein said at least two toothed pulleys are helically geared.
5. A toothed belt drive comprising:
a toothed belt having a plurality of teeth and at least one drive side provided with a first toothed profile;
at least two toothed pulleys each having a circumference and defining tooth gaps;
said at least two toothed pulleys each having a second toothed profile that is complementary to said first toothed profile;
said toothed belt being configured to wrap said at least two toothed pulleys over a part-region of the circumference of each of said at least two toothed pulleys;
said teeth of said toothed belt being configured to mesh in said tooth gaps of said at least two toothed pulleys;
wherein said at least two toothed pulleys have dissimilar diameters and include a smaller toothed pulley and a larger toothed pulley; and, at said smaller toothed pulley an air gap (E S(mk) ) that relates to a nominal pitch (P) and results from a difference between a width (e Smk ) of said tooth gaps of said smaller toothed pulley and a width (e R ) of said teeth of said toothed belt at a mean height of said teeth, depending on a tooth count (z R ) of said toothed belt and on a tooth count (z k ) of said smaller toothed pulley and on (z g ) of said larger toothed pulley, is configured such that:
E
S
(
mk
)
=
e
Smk
-
e
R
=
[
C
S
+
0.004
·
z
z
R
-
z
k
+
(
z
g
z
k
-
1
)
·
C
mk
·
2
π
·
u
P
·
z
g
-
2
π
u
]
·
P
wherein (C S ) is predefined in a range of
0.06≤C S ≤0.08
and (C mk ) is predefined as a modified constant for said air gap in the case of toothed belt drives in a range of
1.00≤C mk ≤2.00.
6. The toothed belt drive of claim 5 , wherein said smaller toothed pulley has a pitch circle diameter of (d)≤45 mm.
7. The toothed belt drive of claim 5 , wherein said smaller toothed pulley has a tooth count between 20 and 60.
8. The toothed belt drive of claim 5 , wherein said at least two toothed pulleys are helically geared.
9. A toothed pulley for use in a toothed belt drive having a toothed belt provided with a first toothed profile including teeth, the toothed pulley comprising:
a toothed pulley body having a circumference and teeth defining tooth gaps therebetween;
said toothed pulley body having a second toothed profile that is complementary to the first toothed profile;
said toothed pulley body being configured to have the toothed belt wrapped over a part-region of the circumference of said toothed pulley body;
said toothed gaps being configured to have the teeth of the toothed belt mesh therein; and,
wherein a backlash of said toothed pulley body is configured such that an air gap (E S ) that relates to a nominal pitch (P) and results from a difference between a width (e S ) of the tooth gaps of said toothed pulley body and a width (e R ) of the teeth of the toothed belt at a mean height of said teeth, depending on a tooth count (z R ) of the toothed belt and on a tooth count (z) of said toothed pulley body, is configured such that
E
S
=
e
S
-
e
R
=
[
C
S
+
0.004
·
z
z
R
-
z
]
·
P
wherein (C S ) is predefined as a constant for a standard backlash in the case of toothed belt drives in a range of
0.06≤C S ≤0.08.
10. The toothed pulley of claim 9 , wherein the toothed belt drive is of an electric steering gear.
11. An electric power steering gear for motor vehicles comprising:
a toothed belt drive including a toothed belt having a plurality of teeth and at least one drive side provided with a first toothed profile;
said toothed belt drive further including at least two toothed pulleys each having a circumference and defining tooth gaps;
said toothed pulleys each having a second toothed profile that is complementary to said first toothed profile;
said toothed belt being configured to wrap said at least two toothed pulleys over a part-region of the circumference of each of said at least two toothed pulleys;
said teeth of said toothed belt being configured to mesh in said tooth gaps of said at least two toothed pulleys;
wherein an air gap (E S ) that relates to a nominal pitch (P) and results from a difference between a width (e S ) of the tooth gaps of the respective one of said at least two toothed pulleys and a width (e R ) of said teeth of said toothed belt at a mean height of said teeth, depending on a tooth count (z R ) of said toothed belt and on a tooth count (z) of said respective one of said at least two toothed pulleys, is configured such that
E
S
=
e
S
-
e
R
=
[
C
S
+
0.004
·
z
z
R
-
z
]
·
P
wherein (C S ) is predefined as a constant for a standard backlash in the case of toothed belt drives in a range of
0.06≤C S ≤0.08.