Transmission cover with improved airflow

Patent metadata

Field	Value
Publication number	US-9366331-B2
Application number	US-201313948007-A
Country	US
Kind code	B2
Filing date	Jul 22, 2013
Priority date	Jul 22, 2013
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A cover for a transmission having improved airflow path is disclosed. The interior of the cover has a progressively narrowing airflow path to reduce pressure drop through the cover, thereby improving the cooling efficiency of the airflow through the cover. The cover includes a diverter sheltering the air inlet to the cover to prevent air in the cover from exerting outward pressure on the incoming air.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A case for a continuously variable transmission having a drive clutch and a driven clutch held by a drive shaft and a driven shaft respectively, wherein the drive shaft and the driven shaft are offset in a longitudinal direction, each of the drive and the driven shafts extends in a lateral direction that is orthogonal to the longitudinal direction, and a vertical direction is transverse to each of the longitudinal direction and the lateral direction, wherein the drive and driven clutches include side faces, the case comprising:
an air inlet extending through an inlet end of the case;
an air outlet extending through an outlet end of the case, wherein the outlet end is substantially opposite the inlet end of the case; and
an airflow channel within the case that guides at least a portion of flowing air from the air inlet downstream to the air outlet, wherein the airflow channel has a ramp region that is downstream from the air inlet and upstream from the air outlet and,
wherein the ramp region includes a lower internal surface, an upper internal surface offset from the lower internal surface in the vertical direction, an upstream ramp portion, and a downstream ramp portion that is downstream from the upstream ramp portion,
wherein a vertical height of the ramp region corresponds to a vertical distance, in the vertical direction, between the upper and the lower internal surfaces of the ramp region and,
wherein the vertical distance between the upper and the lower internal surfaces of the ramp region varies along the longitudinal direction such that a vertical height of the upstream ramp portion is less than a vertical height of the downstream ramp portion.

2. The case of claim 1 , further comprising a drive shaft hole configured and arranged to receive the drive shaft, a driven shaft hole configured and arranged to receive the driven shaft, a high region that is vertically above the ramp region, and a ridge that is intermediate, in the vertical direction, the high region and the ramp region such that the ridge at least partially separates the high region from the ramp region and extends in the longitudinal direction and tangentially from the drive shaft hole to the driven shaft hole, wherein the ridge at least partially restricts a portion of the airflow channel that is downstream of the air outlet and the upper internal surface of the ramp region is at least partially formed by the ridge.

3. The case of claim 1 , wherein the airflow channel further includes a shallow region that is downstream of the ramp region and a deep region that is upstream of the ramp region, wherein a lateral depth of the airflow channel corresponds to a lateral distance, in the lateral direction, between an inboard lateral surface and an outboard lateral surface of the airflow channel, and
wherein, within the ramp region, the lateral distance between the inboard and the outboard lateral surfaces of the airflow channel varies along the longitudinal direction such that a lateral depth of the deep region is greater than a lateral depth of the shallow region.

4. The case of claim 3 , wherein the lateral depth of the airflow channel is greatest in a portion of the deep region that is positioned adjacent the air inlet.

5. The case of claim 3 , wherein the lateral depth of the airflow channel is smallest in a portion of the shallow region that is positioned adjacent the air outlet.

6. The case of claim 3 , wherein a lateral depth of the upstream ramp portion is greater than a lateral depth of the downstream ramp portion of the ramp region.

7. The case of claim 3 , wherein a vertical height of the shallow region is greater than a vertical height of the deep region.

8. The case of claim 1 , further comprising an air diverter that is adjacent the air inlet, the air diverter guiding flowing air downstream from the air outlet into a portion of the airflow channel that is downstream from the air inlet.

9. The case of claim 1 , further including a drive shaft hole and a driven shaft hole, wherein at least a portion of the airflow channel extends in the longitudinal direction and along adjacent portions of the case that form the drive and the driven shaft holes.

10. The case of claim 1 , wherein the case further comprises, a first case part, a second case part, and a plurality of bosses for coupling the first and the second case parts together, the plurality of bosses being positioned on an external portion of the case, wherein an interior surface of the case is adjacent the airflow channel and is substantially smooth.

11. A cover for a transmission having a drive shaft and a driven shaft, wherein the drive shaft and the driven shaft are offset in a longitudinal direction, each of the drive and driven shafts extends in a lateral direction that is orthogonal to the longitudinal direction, and a vertical direction is transverse to each of the longitudinal direction and the lateral direction, the cover comprising:
a first cover portion;
a second cover portion that is configured and arranged to couple to the first cover portion;
a first hole in one of the first or the second cover portions for receiving the drive shaft of the transmission;
a second hole in the one of the first or the second cover portions for receiving the driven shaft of the transmission;
an air inlet disposed near the first hole;
an air outlet disposed near the second hole;
a deep region disposed near the air inlet;
a shallow region disposed near the air outlet;
a ramp region, wherein at least a portion of the ramp region is disposed intermediate, in the longitudinal direction, the deep region and the shallow region and intermediate, in the longitudinal direction, the air inlet and the air outlet, and
wherein the ramp region including a lower internal surface that includes a first normal vector, an upper internal surface that includes a second normal vector and is offset from the lower internal surface in the vertical direction, an upstream ramp portion, and a downstream ramp portion that is disposed intermediate, in the longitudinal direction, the upstream ramp portion and the shallow region, wherein each of the first and the second normal vectors extend in the vertical direction, and
wherein a vertical height of the ramp region corresponds to a vertical distance, in the vertical direction, between the upper and the lower internal surfaces of the ramp region and,
wherein the vertical distance between the upper and the lower internal surfaces of the ramp region varies along the longitudinal direction such that a vertical height of the upstream ramp portion is less than a vertical height of the downstream ramp portion, and
wherein at least a portion of air flowing through the cover enters the case through the air inlet, flows downstream through the deep region, the ramp region, and the shallow region, and exits the cover through the air outlet;
a high region disposed intermediate, in the longitudinal direction, the air outlet and air inlet, wherein the high region is configured and arranged to direct a portion of air flowing downstream from the shallow region to merge with incoming flowing air from the air inlet;
a ridge disposed intermediate, in the longitudinal direction, the first and the second holes that at least partially separates the ramp region from the high region; and
a diverter disposed intermediate the high region and the air inlet and configured and arranged to direct at least a portion of air flowing from the high region, such that a pressure exerted by the directed air on incoming air from the air inlet is at least partially attenuate

Assignees

• Arctic Cat Inc

Inventors

• Eberhardt Ryan

Classifications

• F16H57/0489

  with endless flexible members, e.g. belt CVTs · CPC title

• F16H57/031

  characterised by covers or lids for gearboxes · CPC title

• F16H57/0416 Primary

  Air cooling or ventilation · CPC title

• F16H57/035

  Gearboxes for gearing with endless flexible members · CPC title

• F16H9/12

  engaging a pulley built-up out of relatively axially-adjustable parts in which the belt engages the opposite flanges of the pulley directly without interposed belt-supporting members · CPC title