US20200025208A1

US20200025208A1 - Variable pitch fan assembly with blade pitch indication

Info

Publication number: US20200025208A1
Application number: US16/042,250
Authority: US
Inventors: Shaun J. Miller
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2018-07-23
Filing date: 2018-07-23
Publication date: 2020-01-23
Also published as: BR102019009976A2; CN110748501A

Abstract

A variable pitch fan assembly comprises a fan configured to rotate about a fan rotation axis and comprising blades with a pitch that is variable, a piston connected to the fan and configured to move axially relative to the fan rotation axis to change the pitch of the blades, a rotary crank arm yieldably biased toward the piston, and a motion transmitter positioned in communication with the piston and the crank arm to transmit motion axially therebetween relative to the fan rotation axis, and a sensor positioned to detect an angular position of the crank arm, the angular position indicative of the pitch of the blades.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to a variable pitch fan assembly.

BACKGROUND OF THE DISCLOSURE

It is common for vehicles to employ a fan for cooling purposes. The fan may be used to cool various components of the vehicle, such as the engine and coolers or other heat exchangers.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a variable pitch fan assembly comprises a fan configured to rotate about a fan rotation axis and comprising blades with a pitch that is variable, a piston connected to the fan and configured to move axially relative to the fan rotation axis to change the pitch of the blades, a rotary crank arm yieldably biased toward the piston, and a motion transmitter positioned in communication with the piston and the crank arm to transmit motion axially therebetween relative to the fan rotation axis, and a sensor positioned to detect an angular position of the crank arm, the angular position indicative of the pitch of the blades.
The variable pitch fan assembly may be included in a vehicle. The sensor may generate a position signal indicative of the angular position and thus indicative of the blade pitch. A control system of the vehicle may determine the blade pitch based on the position signal, and command the fan to a desired blade pitch to modulate airflow to a desired level. The control system may do so by controlling the axial position of the piston relative to the fan rotation axis.
The above and other features will become apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings refers to the accompanying figures in which:

FIG. 1 is an elevation view of a vehicle with a portion broken away showing a variable pitch fan assembly;

FIG. 2 is a perspective view showing the variable pitch fan assembly;

FIG. 3 is a partially exploded perspective view, taken along section lines 3-3 (with some portions remaining in solid);

FIG. 4 is an elevational view of the section of FIG. 3, with some portions removed;

FIG. 5 is an enlarged view of a portion of FIG. 4; and

FIG. 6 is an enlarged view of another portion of FIG. 4.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, a vehicle 10 comprises a variable pitch fan assembly 12. The fan assembly 12 is configured for cooling components of the vehicle 10, such as the engine and various coolers or other heat exchangers. The vehicle 10 may be any of a wide variety of vehicles, including, without limitation, agricultural, construction, or forestry vehicles. Illustratively, the vehicle 10 is a cotton harvester.
Referring to FIG. 2, the fan assembly 12 comprises a fan 14 with blades 16 (e.g., 9 blades). The blades 16 have a pitch that is variable to modulate airflow to a desired level. The fan 14 with its blades 16 is configured to rotate about a fan rotation axis 17, and may be driven for rotation about the axis 17 in a conventional manner, such as, for example, hydraulically or pneumatically.
The fan 14 comprises a hub 18 and a sheave 20, the hub 18 and the sheave 20 included in a fan housing 21 of the fan 14. The blades 16 are mounted to the hub 18 in, for example, a conventional manner to rotate with the hub 18 about the fan rotation axis 15. The sheave 20 is fastened to the hub 18 in fixed relation thereto. The sheave 20 is mounted to a housing 22 of the fan assembly 12 via a bearing 23 (e.g., double tapered roller bearing), positioned between the housing 22 and the sheave 20, for rotation relative to the housing 22 about the fan rotation axis 15. The bearing 23 is captured between a snap ring for the outer race and a retainer ring threaded onto the housing 22. As such, the fan 14 is supported for rotation relative to the housing 22 about the fan rotation axis 15.
Referring to FIGS. 3 and 4, the fan assembly 12 comprises a piston 24 connected to the blades 16 to change the pitch of the blades 16. The piston is configured to rotate with the fan 14 about the fan rotation axis, and is configured to move axially relative to the fan rotation axis 15 to change the pitch of the blades 16.
The piston 24 moves in first and second axial directions 26, 28 relative to the axis 15 to change the pitch of the blades 16. The piston 24 may be actuated fluidly, such as hydraulically, in the first axial direction 26 relative to the axis 15. In other embodiments, the piston 24 may be actuated pneumatically, or in another manner, in the first axial direction 26. The piston 24 is yieldably biased in the second axial direction 28 opposite to the first axial direction 26 by a plurality of springs 29 positioned about the axis 15 between the piston 24 and the fan housing 21 (e.g., the sheave 20 of the fan housing 21) and in respective spring-receiving pockets of the piston 24.
Movement of the piston 24 in either direction 26, 28 causes the blades 16 to rotate correspondingly about their respective axes of rotation to change their pitch. A rack and a pinion may be associated with each blade 16 to rotate the blade 16 (racks and pinions not shown). In such a case, each rack may be mounted to the piston 24 for axial movement therewith relative to the axis 15, and each blade 16 may be over-molded or otherwise connected to a respective pinion that meshes with a respective rack. Axial movement of the piston 24 and the racks mounted thereto causes the pinions and the blades 16 mounted respectively thereto to rotate and thereby change the pitch of the blades 16.
The fan assembly 12 comprises a rotary crank arm 30, a motion transmitter 32, and a sensor 34 (FIG. 3). The crank arm 30 is yieldably biased toward the piston 24 in the first axial direction 26 and mounted to the housing 22 to rotate relative to the housing 22 about a crank rotation axis 36. The motion transmitter 32 is positioned in communication with the piston 24 and the crank arm 30 to transmit motion axially therebetween relative to the fan rotation axis 15. The sensor 34 is positioned to detect an angular position of the crank arm 30 relative to the crank rotation axis 36. The angular position is indicative of the pitch of the blades 16.
Referring to FIGS. 3-5, the fan assembly 12 comprises a bearing 38 mounted to the motion transmitter 32 for the piston 24. The piston 24 is connected to the motion transmitter 32 via the bearing 38 such that the piston 24 is configured to rotate relative to the motion transmitter 32 with the fan 14 about the fan rotation axis 15.
Referring to FIGS. 4 and 5, the fan assembly 12 comprises a spacer 40. The spacer 40 contacts the bearing 38 and the piston 24, with a biaser 60 urging the spacer 40 in the second axial direction 28 into contact with the piston 24. The spacer 40 contacts the outer race 42 of the bearing 38, and spaces the piston 24 axially apart from the inner race 44 of the bearing 38 relative to the fan rotation axis 15.
The spacer 40 is supported on the outer race 42. A ring 46 of the spacer 40 surrounds the outer race 42. A lip 48 of the spacer 40 extends radially from the ring 46 relative to the fan rotation axis 15 and axially between the bearing 38 and the piston 24 relation to the fan rotation axis 14 so as to space the piston 24 axially apart from the inner race 44 relative to the fan rotation axis 15. The spacer 40 is configured, for example, as a cap pressed onto the outer race 42 to establish an interference fit therebetween, and is made, for example, of steel.
Referring to FIGS. 3, 4, and 6, the housing 22 comprises a cavity 50 and a bore 52 extending from the cavity 50 axially relative to the fan rotation axis 15. The crank arm 30 is positioned in the cavity 50. The motion transmitter 32 is positioned in the bore 52 for linear movement therein along the fan rotation axis 15 in the first and second axial directions 26, 28. Two bushings 54 of the fan assembly 12, made, for example, of bronze, are pressed into the bore 52 so as to be positioned in the bore 52 in spaced apart relation to one another. The motion transmitter 32 is positioned in the bushings 54 so as to be supported thereby in the bore 52 for axial and rotational movement relative to the fan rotation axis 15 and relative to the bushings 54 and the housing 22. Rotation of the motion transmitter 32 may be induced by rotation of the piston 24 mounted to the motion transmitter 32 via the bearing 38 and the spacer 40. As such, the motion transmitter 32 is mounted for both axial and rotational movement about the fan rotation axis 15.
The motion transmitter 32 is positioned to transmit motion linearly between the piston 24 and the crank arm 30 along the fan rotation axis 15. The motion transmitter 32 may be configured, for example, as a rod or other suitable linear member for such linear movement.
Referring to FIG. 6, the crank arm 30 is positioned in the cavity 50, and is mounted to the housing 22 for rotation about the crank rotation axis 36. The crank arm 30 is integrated with an axle 56 to form a one-piece construction, although in other embodiments the crank arm 30 and the axle 56 may be separate components. The axle 56 is mounted for rotation about the crank rotation axis 36 via two bearings 58 (e.g., needle roller bearings). Each bearing 58 is mounted in a corresponding small bore of the housing 22. The crank arm 30 extends radially from the axle 56 relative to the crank rotation axis 36.
A biaser 60 yieldably biases the crank arm 30 toward the piston 24. The biaser 60 is configured, for example, as a torsion spring. In such a case, one end of the biaser 60 presses against a post 62 mounted to the crank arm 30 (e.g., threaded or pressed into the crank arm 30), and the opposite end of the biaser 60 presses against a tab 64 of the housing 22 positioned in the cavity 50 (the portion of the tab 64 that the biaser 60 contacts is not actually shown but is indicated in FIG. 4 and would be understood by one of ordinary skill in the art).
The motion transmitter 32 and the crank arm 30 are positioned in slidable contact with one another. The motion transmitter 32 and the crank arm 30 cooperate to provide a spherical interface 66 therebetween. The spherical interface 66 inhibits axial play of the crank arm 30 and the axle 56 along the crank rotation axis 36, and accommodates rotation of the motion transmitter 32 about the fan rotation axis 15.
The crank arm 30 comprises a groove 68, and the motion transmitter 32 comprises an end portion 60 received in the groove 68. Illustratively, the end portion 70 is spherical, and the groove 68 is a spherical groove receiving the spherical end portion 70. The groove 68 extends lengthwise along a periphery 72 of the crank arm 30, and lies in an imaginary plane 74 perpendicular to the crank rotation axis 36 (the plane 74 (the plane 74 coincides with the section plane of FIG. 6 and is indicated in FIG. 6 as a dashed box for sake of illustration). The groove 68 may be machined into the periphery 72.
The spherical interface 66 may be wear resistant. The motion transmitter 32 may be made, for example, of stainless steel so as to be anti-corrosive. The crank arm 30 and axle 56 may be made, for example, of hardened steel (e.g., heat-treated) so as to be wear-resistant and not wear prematurely.
As such, the motion transmitter 32 and the crank arm 30 slide against one another when the motion transmitter 32 and the piston 24 move along the fan rotation axis 15 in the first and second axial directions 26, 28. In this way, motion is converted between rotary motion of the crank arm 30 and linear motion of the motion transmitter 32 and the piston 24. As the motion transmitter 32 and the piston 24 move axially along the fan rotation axis 15, the blades 16 rotate proportionally to this axial and linear movement of the motion transmitter 32 and piston 24.
The axle 56 and the sensor 34 are connected to one another such that rotation of the crank arm 30 about the crank rotation axis 36 is detected by the sensor 34 via corresponding rotation of the axle 56 about the crank rotation axis 36. In an embodiment, the axle 56 and the sensor 34 may be keyed to one another such that rotation of the axle 56 causes rotation of a corresponding sleeve of the sensor 34. A key of the sleeve may be received by a keyway of the axle 56. In other embodiments, the axle 56 and the sleeve may have the key and the keyway, respectively. The axle 56 and the sensor 34 may be connected to one another in other ways (e.g., splined, or interference fit).
The sensor 34 detects the angular position of the crank arm 30 relative to the crank rotation axis 36, with the angular position being indicative of the pitch of the blades 16. The sensor 34 may be configured, for example, as a rotary potentiometer that outputs a position signal (e.g., analog), proportional to the pitch of the blades 16. The position signal is proportional to the angular position of the crank arm 30 and thus the blade pitch. As such, the position is indicative the angular position and the blade pitch. The position signal may be used in by a control system on board the vehicle 10 to control the blades 16 to a desired blade pitch to modulate airflow to a desired level. The control system (e.g., a controller thereof) may receive the position signal and determine the blade pitch based on the position signal. The control system may then control the blade pitch via the axial position of the piston 24 relative to the fan rotation axis 15.
While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other variations and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.

Claims

What is claimed is:

1. A variable pitch fan assembly, comprising:

a fan configured to rotate about a fan rotation axis and comprising blades with a pitch that is variable,

a piston connected to the fan and configured to move axially relative to the fan rotation axis to change the pitch of the blades,

a rotary crank arm yieldably biased toward the piston,

a motion transmitter positioned in communication with the piston and the crank arm to transmit motion axially therebetween relative to the fan rotation axis, and

a sensor positioned to detect an angular position of the crank arm, the angular position indicative of the pitch of the blades.

2. The variable pitch fan assembly of claim 1, comprising a bearing mounted to the motion transmitter, wherein the piston is connected to the motion transmitter via the bearing such that the piston is configured to rotate relative to the motion transmitter with the fan about the fan rotation axis.

3. The variable pitch fan assembly of claim 2, comprising a spacer, wherein the bearing comprises an outer race and an inner race, and the spacer is supported on the outer race and spaces the piston apart from the inner race.

4. The variable pitch fan assembly of claim 3, wherein the spacer contacts the bearing and the piston and comprises a ring surrounding the outer race and a lip extending radially from the ring relative to the fan rotation axis and axially between the bearing and the piston relative to the fan rotation axis so as to space the piston axially apart from the inner race relative to the fan rotation axis.

5. The variable pitch fan assembly of claim 2, comprising a housing and a bushing positioned in a bore of the housing, wherein the motion transmitter is positioned in the bushing for axial and rotational movement relative to the fan rotational axis.

6. The variable pitch fan assembly of claim 1, comprising a housing, wherein the fan is supported for rotation relative to the housing about the fan rotation axis, the housing comprises a cavity and a bore extending from the cavity, the crank arm is positioned in the cavity, and the motion transmitter is positioned in the bore for linear movement therein along the fan rotation axis.

7. The variable pitch fan assembly of claim 6, comprising a bushing positioned in the bore, and the motion transmitter is positioned in the bushing.

8. The variable pitch fan assembly of claim 1, wherein the motion transmitter and the crank arm are positioned in slidable contact with one another.

9. The variable pitch fan assembly of claim 1, wherein the crank arm comprises a groove, and the motion transmitter comprises an end portion received in the groove.

10. The variable pitch fan assembly of claim 1, wherein the motion transmitter and the crank arm cooperate to provide a spherical interface therebetween.

11. The variable pitch fan assembly of claim 10, wherein the motion transmitter comprises a spherical end portion, and the crank arm comprises a spherical groove receiving the spherical end portion.

12. The variable pitch fan assembly of claim 11, wherein the spherical groove extends lengthwise along a periphery of the crank arm.

13. The variable pitch fan assembly of claim 11, wherein the crank arm is configured to rotate about a crank rotation axis, and the spherical groove lies in an imaginary plane perpendicular to the crank rotation axis.

14. The variable pitch fan assembly of claim 1, wherein the motion transmitter is configured as a rod.

15. The variable pitch fan assembly of claim 1, wherein the motion transmitter is positioned to transmit motion linearly between the piston and the crank arm.