This invention relates in general to power take-offs for transmitting rotational energy from a source of rotational energy to a rotatably driven accessory. In particular, this invention relates to an improved structure for such a power take-off that includes a force intensifying, multi-chambered, clutch actuator.
A power take-off is a well-known mechanical device that is often used in conjunction with a source of rotational energy, such as a vehicle engine or transmission, to transfer rotational energy to a rotatably driven accessory, such as a hydraulic pump that is supported on the vehicle. For example, power take-offs are commonly used on industrial and agricultural vehicles to transfer rotational energy from the vehicle engine or transmission to one or more hydraulic pumps that, in turn, are used to operate one or more hydraulically driven accessories provided on the vehicle, such as plows, trash compactors, lifting mechanisms, winches, and the like. The power take-off provides a simple, inexpensive, and convenient means for transferring energy from the source of rotational energy to the hydraulic pump that, in turn, can be operated to transfer relatively high pressure fluid to operate the driven accessory.
A typical power take-off includes a housing, an input mechanism, and an output mechanism. The power take-off housing is adapted to be supported on a housing of the source of rotational energy. The power take-off housing includes an opening that is aligned with a corresponding opening provided in the housing of the source of rotational energy. The input mechanism of the power take-off includes a portion (typically a spur gear) that extends outwardly from the power take-off housing through the aligned openings and into the housing of the source of rotational energy. In this manner, the input mechanism of the power take-off is connected to the source of rotational energy so as to be rotatably driven whenever the source of rotational energy is operated. The output mechanism of the power take-off is rotatably driven by the input mechanism and is adapted to be connected to the rotatably driven accessory. In some instances, the input mechanism of the power take-off is directly connected to the output mechanism such that the rotatably driven accessory is operated whenever the source of rotational energy is operated. In other instances, a clutch assembly is provided between the input mechanism and the output mechanism such that the rotatably driven accessory is operated only when the clutch assembly is engaged while the source of rotational energy is operated.
In some instances, the power take-off may be designed to allow the clutch assembly to be safely engaged and/or disengaged at any time without any decoupling gears within the power take-off gear train (including when the power take-off is being rotatably driven by the source of rotational energy and, therefore, while torque is being transmitted through the power take-off). Such power take-offs (often referred to as hot-shift power take-offs) utilize pressurized fluid from the transmission to actuate the clutch assembly, which permits the output shaft of the power take-off to be decoupled from the rotation of the rotatably driven transmission.
It is known that the amount of engagement force that can be exerted by the clutch assembly of the power take-off is directly related to the amount of torque that can be transmitted through the power take-off when it is engaged. Because the size of the clutch assembly is generally related to the amount of this engagement force, the maximum amount of such engagement force is, at least in some instances, limited by the amount of physical space that is available in the vicinity of the vehicle where the power take-off is located.
As vehicular chassis designs become increasingly complicated (and, as a result, the amount of physical space that is available in the vicinity of the vehicle where the power take-off is located becomes increasingly limited), it would be desirable to provide an improved structure for a power take-off that provides additional torque capacity, but does not require a significant additional amount of physical space to be available in the vicinity of the vehicle where the power take-off is located.
The solution to increasing the torque capacity in a power take-off design has been historically solved by increasing the diameter of the clutch, which increases the surface area upon which the pressurized fluid can act on. One deficiency in this solution, however, occurs when the designs of the chassis components and the transmission case require a smaller power take-off footprint, but still require the same (or greater) torque carrying capacity. This problem has been addressed by increasing the number of clutch plates in the clutch pack of the power take-off, which allows for additional friction surfaces to be acted on by the pressurized fluid available from the transmission without altering the overall diameter thereof. This solution works well for power take-offs having a relatively small number of such clutch plates. However, this solution has diminishing returns as number of clutch plates within the power take-off increases. Thus, it would be desirable to provide an improved structure for a power take-off that provides additional torque capacity, but does not require a significant additional amount of physical space in the vicinity of the vehicle where the power take-off is located.
This invention relates to an improved structure for a power take-off that includes a force intensifying, multi-chambered, clutch actuator that provides additional torque capacity, but does not require a significant additional amount of physical space in the vicinity of the vehicle where the power take-off is located. The power take-off of this invention includes a multiple-chambered clutch system that permits the amount of the engagement force that is generated by the clutch to be increased, without increasing the line pressure from the transmission or the overall diameter of the physical size of the clutch system. This results in additional power density in the clutch and, ultimately, more power-dense solutions and increased-torque capacities.
Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
Referring now to the drawings, there is illustrated in
The illustrated power take-off 10 includes a hollow housing 11 having a mounting surface 11a provided thereon. An opening 11b is provided through the mounting surface 11a of the power take-off housing 11. The power take-off 10 has an input mechanism that includes an input gear 12 that is rotatably supported within the power take-off housing 11. As shown in
The mounting surface 11a of the power take-off housing 11 is adapted to be secured (typically by a plurality of bolts—not shown) to a corresponding mounting surface provided on a housing of a source of rotational energy 100, such as an engine or a transmission of a vehicle. As is well known in the art, the portion of the input gear 12 that extends through the opening 11b of the power take-off housing 11 also extends through a corresponding opening (not shown) provided in the housing of the source of rotational energy 100 into engagement with a driving gear 101 or other mechanism provided therein. Thus, the input gear 12 of the power take-off 10 is rotatably driven whenever the driving gear 101 contained within the source of rotational energy 100 is rotatably driven.
The illustrated input gear 12 is splined onto or otherwise supported on an input gear hub 13 for concurrent rotation to form a conventional input cluster gear. However, it is known to form the input gear 12 and the input gear hub 13 integrally from a single piece of material. In either event, the input gear hub 13 is, in turn, rotatably supported on an input shaft 14 by one or more bearings 15. First and second ends of the illustrated input shaft 14 are respectively (and typically non-rotatably) supported in first and second bores 11c and 11d provided in the power take-off housing 11.
The power take-off 10 also includes a clutch assembly, indicated generally at 16, for selectively connecting the input gear hub 13 (and, thus, the input gear 12 supported thereon) to an output shaft 17. The output shaft 17 is, in turn, adapted to be connected to the rotatably driven accessory (not shown). The illustrated output shaft 17 is rotatably supported on the power take-off housing 11 by a pair of bearings 17a and 17b or other similar means. When the clutch assembly 16 is engaged, the input gear hub 13 is connected to the output shaft 17 for concurrent rotation. Thus, the rotatably driven accessory is rotatably driven by the source of rotational power when the clutch assembly 16 is engaged. Conversely, when the clutch assembly 16 is disengaged, the input gear hub 13 is disconnected from the output shaft 17. Thus, the rotatably driven accessory is not rotatably driven by the source of rotational power when the clutch assembly 16 is disengaged. A conventional shifter assembly, indicated generally at 18, may be provided to selectively engage and disengage the clutch assembly 16 in a known manner.
The clutch assembly 16 of the power take-off 10 includes a drive gear 21 that is rotatably supported on the output shaft 17 by a bearing 22 and is rotatably driven by the input gear hub 13. The illustrated drive gear 21 includes an axially-extending hollow cylindrical bell portion 21a having a splined inner surface. The illustrated drive gear 21 is formed integrally from a single piece of material with the hollow cylindrical bell portion 21a. However, it is known to form the drive gear 21 and the hollow cylindrical bell portion 21a from separate components that are splined or otherwise connected together for concurrent rotation. In either event, a plurality of flat annular clutch plates 23 is splined to the inner splined surface of the hollow cylindrical bell portion 21a of the drive gear 21 for rotation therewith. Thus, the drive gear 21 and the clutch plates 23 are constantly rotatably driven by the input gear 12.
A plurality of annular friction plates 24 is disposed in an alternating fashion between the clutch plates 23. The friction plates 24 are splined to an outer splined surface provided on an axially extending cylindrical portion 25a of a clutch gear 25 for rotation therewith. The clutch gear 25 is splined or otherwise secured to the output shaft 17 for rotation therewith. Thus, the friction plates 24, the clutch gear 25, and the output shaft 17 are connected for rotation together as a unit. The clutch gear 25 is restrained from axial movement in one direction (toward the right when viewing
An annular clutch piston 26 is provided for selectively causing the clutch plates 23 and the friction plates 24 to frictionally engage one another so as to engage the clutch assembly 16. To accomplish this, the clutch piston 26 is disposed within a hollow cylindrical clutch cylinder 27. The clutch cylinder 27 has a closed end and an opened end. One end of the clutch piston 26 (the left end when viewing
A coiled clutch spring 28 reacts between the clutch piston 26 and the clutch gear 25. As discussed above, the clutch gear 25 is restrained from axial movement in one direction (toward the right when viewing
To engage the clutch assembly 16, the shifter assembly 18 is actuated to supply pressurized fluid to an annular clutch chamber 29 defined between the clutch piston 26 and the closed end of the clutch cylinder 27. As a result, the clutch piston 26 is moved axially in the one direction (toward the right when viewing
A clutch cylinder extension 202 is supported on the opened end of the primary clutch cylinder 201. The clutch cylinder extension 202 includes a radially-inwardly extending portion that defines both a first axially-facing surface 202a (the left surface when viewing
A primary clutch piston 203 is supported on the primary clutch cylinder 201 for axial movement relative thereto. In the illustrated embodiment, the primary clutch piston 203 is supported within the primary clutch cylinder 201 between the axially-facing surface 201a of the primary clutch cylinder 201 and the first axially-facing surface 202a of the clutch cylinder extension 202. More specifically, a first axially-facing surface 203a of the primary clutch piston 203 (the left surface when viewing
Additionally, a second axially-facing surface 203b of the primary clutch piston 203 (the right surface when viewing
A secondary clutch piston 206 is supported on the assembly of the primary clutch cylinder 201 and the clutch cylinder extension 202 for axial movement relative thereto. Thus, the clutch cylinder extension 202 functions as a secondary clutch cylinder for supporting the secondary clutch piston 206 of the clutch actuator 200 for such relative axial movement. In the illustrated embodiment, the secondary clutch piston 206 is supported on the assembly of the primary clutch cylinder 201 and the clutch cylinder extension 202 (i.e., the secondary clutch cylinder) such that a first axially-facing surface 206a of the secondary clutch piston 206 (the left surface when viewing
A second axially-facing surface 206b of the secondary clutch piston 206 is disposed adjacent to the assembly of the clutch plates 23 and the friction plates 24 of the power take-off 10 described above. Lastly, the secondary clutch piston 206 includes an annular axially-extending portion 206c that, in the illustrated embodiment, both is supported on the output shaft 17 and supports the annular axially-extending portion 203c of the primary clutch piston 203. The annular axially-extending portion 203c of the primary clutch piston 203 extends axially past the intermediate member 202 and adjacent to the first axially-facing surface 206a of the secondary clutch piston 206. The purposes for these structures will also be explained below.
A clutch spring 208 is positioned to react between the secondary clutch piston 206 of the modified clutch actuator 200 and the clutch gear 25 of the power take-off 10. In the illustrated embodiment, the clutch spring 208 is embodied as a plurality of annular wave springs, although such is not required. As discussed above in connection with
To engage the modified clutch actuator 200, the shifter assembly 18 is actuated to provide a supply of a pressurized fluid to either, or both, of the first pressure chamber 204 and the second pressure chamber 207. The pressurized fluid may be provided from any desired source including, for example, a source of pressurized liquid from a transmission on the vehicle, a source of pressurized air from a compressor tank supported on the vehicle, or any other known or conventional mechanism or apparatus. The pressurized fluid may be supplied to either, or both, of the first pressure chamber 204 and the second pressure chamber 207 in any desired manner, such as through either a single common port or plural separate ports.
When it is desired to actuate the primary clutch piston 203 from the disengaged position (relative to the primary clutch cylinder 201) illustrated in
Thereafter, if it is desired to additionally actuate the secondary clutch piston 206 from the disengaged position (relative to the primary clutch piston 203) illustrated in
In some instances, it may be desirable to actuate only the secondary clutch piston 204 from the disengaged position (relative to the primary clutch piston 203) illustrated in
In each of these instances, the modified clutch actuator 200 causes the clutch plates 23 and the friction plates 24 to frictionally engage one another. As a result, the clutch assembly 16 is engaged to connect clutch gear 25 of the power take-off 10 to the drive gear 21 so as to provide a rotatable driving connection therebetween. Depending upon whether the pressurized fluid has been supplied to only the first pressure chamber 204, only the second pressure chamber 207, or both the first pressure chamber 204 and the second pressure chamber 207, the magnitude of such frictional engagement can be selected or otherwise controlled as desired. When the pressurized fluid is supplied to both the first pressure chamber 204 and the second pressure chamber 207, the illustrated piston-on-piston arrangement effectively increases the overall surface area upon which the pressurized fluid pressure acts, thereby increasing the amount of force that the modified clutch actuator 200 can exert on the assembly of the clutch plates 23 and the friction plates 24. Such increase in the amount of force is desirably accomplished without significantly increasing the overall physical size of the modified clutch actuator 200.
The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
This application claims the benefit of U.S. Provisional Application No. 63/345,466, filed May 25, 2022, the disclosure of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
63345466 | May 2022 | US |