Rotor with magnet positioning tab system
A rotor for an electric machine includes a rotor core having one or more cavities internal to the rotor core, the cavities defined by a wall of the rotor core. Laminations are stacked together to form the rotor core, and the laminations define the cavities. A body or bodies, which may be magnets, extend within the cavities. A subset of the laminations each include a tab system with at least one tab configured to preload the body to a seated position against the wall, and to maintain the bodies in the seated position within the cavity.
1 . A rotor for an electric machine comprising:
a rotor core having at least one cavity internal to the rotor core, the at least one cavity defined by a wall of the rotor core, the wall comprising a radially inner lateral wall section, a radially outer lateral wall section, a radially inner tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a first end of the cavity, and a radially outer tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a second end of the cavity that is opposite the first end of the cavity;
laminations stacked together to form the rotor core, including to form the at least one cavity; and
a body extending within the at least one cavity,
wherein the laminations in a subset of the laminations each include a tab system with tabs configured to preload the body to a seated position against the wall, and to maintain the body in the seated position,
wherein the tabs are disposed at a first corner of the body that is located at a first wall junction that is where the radially inner lateral wall section and the radially inner tip meet each other,
wherein none of the tabs are disposed at a second corner of the body that is located at a second wall junction where the radially inner lateral wall section and the radially outer tip meet each other, and wherein at the second corner the wall forms a stop that mates with a side of the body or forms an angled section of the wall that mates with a beveled surface of the body,
wherein the tabs are configured to force the body against both the radially outer lateral wall section and against the stop or the angled section of the wall.
2 . The rotor of claim 1 , wherein the body comprises a magnet.
3 . The rotor of claim 1 , wherein the body includes chamfered corners, wherein the at least one tab comprises one tab only on each of the laminations in the subset of laminations, wherein the one tab engages the body at one of the chamfered corners.
4 . The rotor of claim 1 , wherein:
the body includes chamfered corners,
the at least one tab comprises one tab, only,
the one tab engages the body at one of the chamfered corners, and
the wall includes the angled section that engages the body at another of the chamfered corners.
5 . The rotor of claim 1 , wherein:
the subset of the laminations is a first subset of the laminations,
the laminations include a second subset of the laminations that is different than in the first subset of the laminations,
the laminations in the second subset of the laminations do not include the tabs and are free of structures that apply force to the body,
the laminations in the second subset of the laminations do include the angled section or the stop.
6 . The rotor of claim 1 , wherein the at least one tab is not included on a majority of the laminations.
7 . The rotor of claim 1 , wherein the wall defines the stop, wherein the tabs include side tabs on the radially inner lateral wall section that force the body against the radially outer lateral wall section.
8 . The rotor of claim 1 , wherein the at least one tab is configured to define a press-fit between the body and the wall to establish the preload.
9 . The rotor of claim 1 , wherein:
the at least one cavity includes groups of cavities disposed to define struts and bridges and flux path elements, and
the angled section and the stop are formed by areas of the laminations on an opposite side of the body from the struts and the bridges and the flux path elements.
10 . The rotor of claim 1 , wherein the rotor is configured to be in a stationary state and to operate by rotating at a speed state, wherein the preload is tuned to maintain the body in the seated position during both the stationary state and the speed state.
11 . A rotor for an electric machine comprising:
a rotor core having cavities internal to the rotor core, the cavities defined by a wall of the rotor core;
laminations stacked together to form the rotor core, the laminations defining the cavities, wherein for each cavity in the cavities, the wall comprises a radially inner lateral wall section, a radially outer lateral wall section, a radially inner tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a first end of the cavity, and a radially outer tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a second end of the cavity that is opposite the first end of the cavity; and
a body comprising a magnet extending within each of the cavities,
wherein the laminations in a subset of the laminations each include a tab system with tabs configured to preload the body to a seated position against the wall, and to maintain the body in the seated position,
wherein the tabs are disposed at a first corner of the body that is located at a first wall junction that is where the radially inner lateral wall section and the radially inner tip meet each other,
wherein none of the tabs are disposed at a second corner of the body that is located at a second wall junction where the radially inner lateral wall section and the radially outer tip meet each other, and wherein at the second corner the wall forms a stop that mates with a side of the body or forms an angled section of the wall that mates with a beveled surface of the body,
wherein the tabs are configured to force the body against both the radially outer lateral wall section and against the stop or the angled section of the wall.
12 . The rotor of claim 11 , wherein the body includes chamfered corners, wherein the subset of the laminations each include one tab only, as the tab, wherein the one tab engages the body at a chamfered corner of the magnet.
13 . The rotor of claim 11 , wherein:
the magnet includes chamfered corners,
the tabs comprise one tab, only, per cavity of the cavities
the one tab engages the body at one of the chamfered corners, and
the wall includes the angled section that engages the body at another of the chamfered corners.
14 . The rotor of claim 11 , wherein:
the subset of the laminations is a first subset of the laminations,
the laminations include a second subset of the laminations that is different than the first subset of the laminations,
the laminations in the second subset of the laminations do not include the tabs and are free of structures that apply force to the body,
the laminations in the second subset of the laminations do include the angled section or the stop.
15 . The rotor of claim 11 , wherein the subset of the laminations is a minority of the laminations so that the tabs are not included on a majority of the laminations.
16 . The rotor of claim 11 , wherein the wall defines the stop, wherein the tabs includes side tabs on the radially inner lateral wall section that force the body against the radially outer lateral wall section.
17 . The rotor of claim 11 , wherein the tabs are configured to define a press-fit between the magnet and the wall to establish the preload, with a gap defined between the wall and the magnet adjacent the at least one tab.
18 . The rotor of claim 11 , wherein:
the at least one cavity includes groups of cavities disposed to define struts and bridges and flux path elements, and
the angled section and the stop are formed by areas of the laminations on an opposite side of the body from the struts and the bridges and the flux path elements.
19 . The rotor of claim 11 , wherein the rotor is configured to alternately be in a stationary state and to operate by rotating at a speed state, wherein the preload is tuned to maintain the magnet in the seated position during both the stationary state and the speed state.
20 . A rotor for an electric machine comprising:
a rotor core having cavities internal to the rotor core, the cavities defined by a wall of the rotor core;
laminations stacked together to form the rotor core, the laminations defining the cavities, wherein for each cavity in the cavities, the wall comprises a radially inner lateral wall section, a radially outer lateral wall section, a radially inner tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a first end of the cavity, and a radially outer tip extending between the radially inner lateral wall section and the radially outer lateral wall section at a second end of the cavity that is opposite the first end of the cavity; and
a magnet extending within each of the cavities,
wherein each of the laminations in a first subset of the laminations includes a tab system with a tab configured to preload the magnet to a seated position against the wall, and to maintain the magnet in the seated position,
wherein the tab is disposed at a first corner of the magnet that is located at a first wall junction that is where the radially inner lateral wall section and the radially inner tip meet each other,
wherein no tab is disposed at a second corner of the magnet that is located at a second wall junction where the radially inner lateral wall section and the radially outer tip meet each other, and wherein at the second corner the wall forms a stop that mates with a side of the magnet or forms an angled section of the wall that mates with a beveled surface of the magnet,
wherein the tab is configured to force the body against both the radially outer lateral wall section and against the stop or the angled section of the wall,
wherein each of the laminations in a second subset of the laminations does not include the tab.