Electrified vehicle with oriented parking mechanism
An electrified vehicle includes a multi-phase electric machine having a rotor with a number of magnetic pole pairs and secured for rotation with an output shaft. A parking gear secured for rotation with the output shaft has external teeth configured to selectively engage a parking pawl. The parking gear, the rotor, and the output shaft include complementary angular alignment features to angularly orient the parking gear relative to the rotor in an angular position offset by an index angle from one of the magnetic poles of the rotor such that occurrences of the parking pawl being engaged with the parking gear during dead time periods of an inverter powering the electric machine are reduced or eliminated.
1 . An electrified vehicle comprising:
a multi-phase electric machine having a first number of phases and including a stator surrounding and separated by an air gap from a rotor having a second number of magnetic pole pairs, the rotor secured for rotation with an output shaft of the electric machine; and
a parking gear secured for rotation with the output shaft of the electric machine and having a third number of external teeth spaced around a circumference configured to selectively engage a parking pawl between adjacent external teeth, wherein the parking gear, the rotor, and the output shaft include complementary angular alignment features to angularly orient the parking gear relative to the rotor in an angular position offset by an index angle from one of the magnetic poles of the rotor, wherein the index angle is based on the first number of phases, the second number of pole pairs, and the third number of external teeth.
2 . The electrified vehicle of claim 1 wherein the third number of external teeth corresponds to a numerical factor of a number equal to two times the first number of phases multiplied by the second number of pole pairs.
3 . The electrified vehicle of claim 2 wherein the electric machine is a three-phase electric machine, the rotor has four magnetic pole pairs, and the parking gear has eight external teeth.
4 . The electrified vehicle of claim 1 wherein the output shaft includes an external spline cooperating with an internal spline of the parking gear to secure the parking gear for rotation with the output shaft, and wherein the complementary angular alignment features include a pattern of omitted ridges around the circumference of one of the output shaft and the parking gear corresponding with a pattern of widened ridges around the circumference of the other of the output shaft and the parking gear.
5 . The electrified vehicle of claim 1 wherein the complementary angular alignment features comprise stamped alignment marks on at least two of the rotor, the parking gear, and the output shaft.
6 . The electrified vehicle of claim 1 , further comprising:
a traction battery; and
an inverter coupled to the traction battery and operable to convert direct current (DC) power from the traction battery to multi-phase alternating current (AC) power provided to the electric machine by controlling a pair of switches associated with each one of the phases of the multi-phase AC power, and having a number of dead time periods when both switches of any of the pairs of switches are off;
wherein the parking gear, the rotor, and the parking pawl are angularly positioned relative to each other to minimize the number of dead time periods that coincide with the parking pawl being aligned between adjacent external teeth of the parking gear.
7 . The electrified vehicle of claim 1 wherein the parking gear comprises asymmetrically spaced external teeth.
8 . The electrified vehicle of claim 7 wherein the external teeth are asymmetrically spaced to minimize a number of dead time periods of an inverter that powers the electric machine that coincide with the parking pawl being aligned between adjacent external teeth of the parking gear.
9 . An electrified vehicle comprising:
a multi-phase electric machine having a first number of phases and including a stator surrounding and separated by an air gap from a rotor having a second number of magnetic pole pairs, the rotor secured for rotation with an output shaft of the electric machine;
a parking gear secured for rotation with the output shaft of the electric machine and having a third number of external teeth spaced around a circumference;
a parking pawl pivotable about a pin to selectively engage the parking gear between adjacent external teeth;
a traction battery; and
an inverter coupled to the traction battery and operable to convert direct current (DC) power from the traction battery to multi-phase alternating current (AC) power provided to the electric machine by controlling a pair of switches associated with each one of the phases of the multi-phase AC power, and having a number of dead time periods when both switches of any of the pairs of switches are off;
wherein the parking gear, the rotor, and the parking pawl are angularly positioned relative to each other to minimize the number of dead time periods that coincide with the parking pawl being aligned between adjacent external teeth of the parking gear.
10 . The electrified vehicle of claim 9 wherein the output shaft includes an external spline cooperating with an internal spline of the parking gear to secure the parking gear for rotation with the output shaft, and wherein the output shaft and the parking gear include complementary patterns of omitted ridges around the circumference of one of the output shaft and the parking gear corresponding with a pattern of widened ridges around the circumference of the other of the output shaft and the parking gear.
11 . The electrified vehicle of claim 9 wherein the parking gear, the rotor, and the output shaft include complementary angular alignment features.
12 . The electrified vehicle of claim 9 wherein the parking gear comprises asymmetrically spaced external teeth.
13 . The electrified vehicle of claim 12 wherein the external teeth are asymmetrically spaced to minimize a number of dead time periods that coincide with the parking pawl being aligned between adjacent external teeth of the parking gear.
14 . The electrified vehicle of claim 9 wherein the parking gear and the output shaft comprise complementary angular alignment features comprising a key on either the parking gear or the output shaft and a complementary slot on the output shaft or the parking gear, respectively.
15 . The electrified vehicle of claim 9 wherein the parking gear, the rotor, and the output shaft include complementary angular alignment features, the complementary alignment features comprising asymmetrical alignment features providing a single angular alignment.
16 . An electrified vehicle comprising:
a multi-phase electric machine having a first number of phases and including a stator surrounding and separated by an air gap from a rotor having a second number of magnetic pole pairs, the rotor secured for rotation with an output shaft of the electric machine;
a parking gear secured for rotation with the output shaft of the electric machine and having a third number of external teeth spaced around a circumference;
a parking pawl pivotable about a pin to selectively engage the parking gear between adjacent external teeth;
a traction battery; and
an inverter coupled to the traction battery and operable to convert direct current (DC) power from the traction battery to multi-phase alternating current (AC) power provided to the electric machine by controlling a pair of switches associated with each one of the phases of the multi-phase AC power, and having a number of dead time periods when both switches of any of the pairs of switches are off;
wherein the parking gear, the rotor, and the output shaft include complementary angular alignment features that angularly position the external teeth of the parking gear relative to magnetic poles of the rotor to minimize the number of dead time periods that coincide with the parking pawl being aligned between adjacent external teeth of the parking gear.
17 . The electrified vehicle of claim 16 wherein the output shaft includes an external spline cooperating with an internal spline of the parking gear to secure the parking gear for rotation with the output shaft, and wherein the complementary angular alignment features include a pattern of omitted ridges around the circumference of one of the output shaft and the parking gear corresponding with a pattern of widened ridges around the circumference of the other of the output shaft and the parking gear.