US 12,398,751 B2Granted

Optimized ball bearing and method of designing an optimized ball bearing

AssigneeAktiebolaget Skf

InventorsTom Schmitz, Kyle J. Monaghan

Life of this patent

Estimating the term…

Abstract

A method of designing a ball bearing includes providing a value of a shaft outside diameter and a load. An inside diameter of a bearing inner ring is determined based on the value of the shaft outside diameter. A ball size having a specific ball diameter is selected and a number of the balls of the selected standard ball size required to support the load is determined. A pitch diameter of a pitch circle of the ball bearing is determined based on the determined number of balls of the selected ball size. A suitability factor is calculated for the particular value of the pitch diameter and the particular pitch diameter is validated as suitable when the suitability factor is between calculated upper and lower limits.

Claims20

Dependent claims

A ball bearing for an electric vehicle, the ball bearing supporting a load applied to a shaft of an electric motor of the vehicle, the ball bearing comprising:

an inner ring having a centerline and an inside diameter, the inside diameter being sized such that the inner ring fits upon the shaft of the electric motor;
an outer ring disposed about the inner ring;
and
a number of balls disposed between the inner ring and the outer ring and traversing a pitch circle extending about the centerline, each ball having a ball diameter and the pitch circle having a pitch diameter, the number of balls and the ball diameter being selected to provide a value of the pitch diameter which satisfies the following equations:
X
=
π
2
*
BD
2
*
PD
*
ID
;
where
⁢
LL
≤
X
≤
UL
;
⁢
UL
=
(
-
2
.
4
⁢
8
⁢
15
*
ID
3
)
+
(
211.6
*
ID
2
)
-
(
4
568.1
*
ID
)
+
38956
;
and
⁢
LL
=
(
-
2
⁢
3
.
5
⁢
11
*
ID
2
)
+
(
2235.9
*
ID
)
-
2
⁢
856
;
wherein X is a suitability factor, BD is the ball diameter, PD is the pitch diameter, ID is the inside diameter of the inner ring, LL is a lower limit and UL is an upper limit.

83 more elements

An electric motor assembly for an electric passenger vehicle, the electric motor assembly comprising:

an electric motor stator enclosed within a housing;
an electric motor rotor disposed at least partially within the stator;
an output shaft connected with the rotor;
and
at least one ball bearing configured to support loading on the motor output shaft, the ball bearing including:
an inner ring having a centerline and an inside diameter, the inside diameter being sized such that the inner ring fits upon the shaft of the electric motor;
an outer ring disposed about the inner ring;
and
a number of balls disposed between the inner ring and the outer ring and traversing a pitch circle extending about the centerline, each ball having a ball diameter and the pitch circle having a pitch diameter, the number of balls and the ball diameter being selected to provide a value of the pitch diameter which satisfies the following equations:
X
=
π
2
*
BD
2
*
PD
*
ID
;
where
⁢
LL
≤
X
≤
UL
;
⁢
UL
=
(
-
2
.
4
⁢
8
⁢
15
*
ID
3
)
+
(
211.6
*
ID
2
)
-
(
4
⁢
5
⁢
6
⁢
8
.1
*
ID
)
+
38956
;
and
⁢
LL
=
(
-
2
⁢
3
.
5
⁢
11
*
ID
2
)
+
(
2235.9
*
ID
)
-
2
⁢
856
;
wherein X is a suitability factor, BD is the ball diameter, PD is the pitch diameter, ID is the inside diameter of the inner ring, LL is a lower limit and UL is an upper limit.

94 more elements

A method of designing a ball bearing to support a predetermined load on a shaft, the method comprising the steps of:

providing a value of an outside diameter of the shaft and a value of the load;
determining an inside diameter (ID) of a bearing inner ring based on the value of the shaft outside diameter;
selecting a ball size having a specific ball diameter (BD);
determining a number (N) of the balls of the selected ball size required to support the load;
determining a pitch diameter (PD) of a pitch circle of the ball bearing based on the determined number of balls of the selected ball size;
and
calculating a suitability factor (X) using the following equation:
X
=
π
2
*
BD
2
*
PD
*
ID
;
and
validating the pitch diameter as suitable for the ball bearing when the suitability factor is between an upper limit (UL) and a lower limit (LL), the upper limit and lower limit being calculated as follows:
UL
⁢
=
(
-
2
.4815
*
ID
3
)
+
(
211.6
*
ID
2
)
-
(
4568.1
*
ID
)
+
38956
;
and
⁢
LL
=
(
-
2
3.511
*
ID
2
)
+
(
2235.9
*
ID
)
-
2
⁢
8
⁢
5
⁢
6
⁢
7
.

74 more elements

Dependencies are inferred from the claim text.

patentgrep

Loading patent…

Abstract