WO2023186337A1

WO2023186337A1 - Overrunning pto clutch for tractor manual transmission

Info

Publication number: WO2023186337A1
Application number: PCT/EP2022/072621
Authority: WO
Inventors: Manoj Babu M; Anoop -
Original assignee: Aktiebolaget Skf
Priority date: 2021-09-07
Filing date: 2022-08-11
Publication date: 2023-10-05

Abstract

Disclosed is a one-way overrunning power take-off (PTO) clutch (100) to restrict transmission of inertial force. The overrunning PTO clutch (100) comprises a case barrel (105) comprising an inner wedge profile and a plastic cage (110) configured to fit inside the barrel (105), wherein the plastic cage (110) comprises a plurality of springs (115) and rolling elements (120), wherein the springs (115) provides the required force to keep the rolling elements (120) in place.

Description

OVERRUNNING PTO CLUTCH FOR TRACTOR MANUAL TRANSMISSION

FIELD OF THE INVENTION

[001] The present disclosure generally relates to power take-off (PTO) clutch, and more particularly relates to an overrunning PTO clutch that prevents transmission of the torque back into the input shaft during manual transmission in a tractor.

BACKGROUND OF THE INVENTION

[002] Typically, a tractor has a power take-off (PTO) shaft that is positioned in between the tractor and an attachment. The PTO shaft enables the transfer of rotational power and torque from the tractor engine to the attachment, the attachment could be any piece of equipment that does not have its own engine or motor. To control power transfer, an overrunning PTO clutch is provided. An overrunning PTO clutch is a device that allows a tractor's PTO shaft to be driven in one direction and to spin freely (freewheel) in the opposite direction. When the clutch is engaged, the power is transmitted to the attachment, and when the clutch is disengaged the PTO shaft is not driven.

[003] The PTO clutch is designed to prevent torque from being transferred to the opposite direction. Overrunning PTO clutch for manual transmission are usually an external attachment on the PTO shaft. Being external, it is susceptible to getting contaminated due to external contaminants and dirt. Further, being an external attachment, the PTO clutch requires regular grease lubrication.

[004] Therefore, there is a need for an improved overrunning PTO clutch to prevent torque from being transferred to the opposite direction and one that requires minimal maintenance.

BRIEF SUMMARY OF THE INVENTION

[005] This summary is provided to introduce a selection of concepts in a simple manner that is further described in the detailed description of the disclosure. This summary is not intended to identify key or essential inventive concepts of the subject matter nor is it intended for determining the scope of the disclosure.

[006] The present disclosure discloses a one-way overrunning power take-off (PTO) clutch to restrict transmission of inertial force from PTO shaft to input shaft. The overrunning PTO clutch comprises a case barrel comprising an inner wedge profile and a plastic cage configured to fit inside the barrel, wherein the plastic cage comprises a plurality of springs and rolling elements, wherein the springs provides the required force to keep the rolling elements in place.

[007] To further clarify advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof, which is illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained with additional specificity and detail with the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

[008] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:

[009] FIGURE 1 illustrates a one-way overrunning power take-off (PTO) clutch, in accordance with an embodiment of the present disclosure; and

[0010] FIGURE 2A and FIGURE 2B illustrates a cross section view of the PTO clutch, in accordance with an embodiment of the present disclosure.

[0011] Further, persons skilled in the art to which this disclosure belongs will appreciate that elements in the figures are illustrated for simplicity and may not have been necessarily drawn to scale. Furthermore, in terms of the construction of the PTO clutch may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION

[0012] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications to the disclosure, and such further applications of the principles of the disclosure as described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates are deemed to be a part of this disclosure.

[0013] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.

[0014] In the present disclosure, relational terms such as first and second, and the like, may be used to distinguish one entity from the other, without necessarily implying any actual relationship or order between such entities.

[0015] The terms "comprise", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or a method. Similarly, one or more elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other elements, other structures, other components, additional devices, additional elements, additional structures, or additional components. Appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. [0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The components, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0017] The following paragraphs discusses the structure and function of the overrunning PTO clutch in detail. The invention proposes a compact overrunning clutch to restrict the driven equipment from transmitting inertial force on the PTO shaft and the transmission. Unlike conventional solutions that has an external overrunning clutch, the PTO clutch in the present invention is fully positioned inside the gear box fixed directly between the input and PTO shaft, making it work with continuous proper lubrication and precision.

[0018] FIGURE 1 illustrates a structural diagram of a one-way overrunning power take-off (PTO) clutch 100, in accordance with an embodiment of the present disclosure. The one-way overrunning PTO clutch is designed in such a way that it restricts transmission of inertial force, i.e. to prevent torque from being applied in the opposite direction.

[0019] The overrunning PTO clutch 100 includes a case barrel 105 comprising an inner wedge profile. The overrunning PTO clutch 100 includes a plastic cage 110 configured to fit inside the barrel 105. The plastic cage 110 includes a plurality of springs 115 and rolling elements 120. The springs 115 provide the required force to keep the rolling elements 120 in place. The plastic cage 110 has an opening to expel sludge. This automatic design to expel sludge reduces the burden of frequent maintenance.

[0020] The overrunning PTO clutch 100 is fixed between an input shaft and a PTO shaft.

A flange 130 accommodating an input shaft is fastened on to the case barrel 105 at an input end of the overrunning PTO clutch 100. An input lock plate 135 is fastened between the flange 130 and the barrel 105 using a fastener 160. The input lock plate 135 includes slots for lubrication. The flange 130 comprises a bush 140 to guide the input shaft. The PTO shaft is coupled to a ring shaft 125 at an output end of the overrunning PTO clutch 100. The outer surface of the ring shaft 125 acts as the raceway for the rolling elements 120. An output lock plate 145 is slidingly fit over the ring shaft 125 and is fastened using a circlip 150. Like the input lock plate 135, the output lock plate 145 too includes slots for lubrication. The input lock plate 135 and the output lock plate 145 ensures the plastic cage 110 and components housed inside the cage do not engage in relative axial movement. The overrunning PTO clutch 100 is enclosed within the end lock plates 135, 145 and is fastened by circlips 150, 155. The input and PTO shaft are splined to enable the axial motion. Necessary staked up clearance is provided between the circlips 150, 155 to accommodate axial play during operation.

[0021] The overrunning PTO clutch 100 when engaged allows the PTO shaft to keep running without transmitting torque back into the input shaft. The overrunning PTO clutch 100 is designed to be compact and can be constituted inside a gear box. It is to be noted that, being enclosed inside the gear box, helps the PTO clutch from contamination due to external contaminants and dirt. Further, since the overrunning PTO clutch 100 is within the gear box, the lubrication for the overrunning PTO clutch 100 is provided by the oil media inside the gear box.

[0022] FIGURE 2A and FIGURE 2B illustrates a cross section view of the PTO clutch, in accordance with an embodiment of the present disclosure. The functioning of the PTO clutch is further explained in conjunction with FIGURE 2A and FIGURE 2B.

[0023] The overrunning PTO clutch consists of a one way clutch which has four types of components. A barrel incorporates the wedge profile required to lock the rolling element. A polymer cage fits inside the barrel and houses the springs and the roller. In one embodiment, on the input side, the splined input shaft fits into the splines on the flange and on the output side, the splined PTO shaft fits into the splines on the ring shaft.

[0024] Working - Torque mode: When the input shaft rotates in the torque transmitting direction, it rotates the flange in the same direction. The barrel is hence rotated along. The rolling elements get locked in the wedge and hence there is no relative movement. The ring shaft hence rotates along with one way clutch. So the PTO shaft that is fixed inside the ring shaft also rotates along in the same direction as the input shaft as depicted in FIGURE 2A.

[0025] Working - Overrunning mode: When the tractor clutch is engaged, the input shaft stops rotating. However the PTO shaft keeps rotating due to its inertia. The ring shaft rotates along with the PTO shaft. The rolling elements are pushed out of the wedge and starts rotating over the ring shaft race way. Hence the rolling element does not transmit the rotation / torque from the PTO shaft to the barrel as depicted in FIGURE 2B. And there is no rotation of the flange as well. Finally there is no rotation transmitted to the input shaft as well, thus achieving the primary purpose of the product. It is to be noted that the direction of rotation is not limiting, and in one embodiment of the present disclosure, the input rotation is anti-clockwise with rotation of other components correspondingly getting changed. In another embodiment, the circlip 145 is replaced by a positive step on the ring shaft 125 and a bush 140 could be provided as guide inside the ring shaft similar to input side flange.

[0026] The one-way overrunning PTO clutch has several advantages. When the clutch is engaged, the PTO shaft keeps running on its inertia without transmitting the torque back into the input shaft. The overrunning PTO clutch is reliable, rigid, and discrete, and can handle wide range of sizes, torque and disengaging rpms. Each component within the overrunning PTO clutch and the components coupled to the overrunning PTO clutch is designed to give the entire system advantage over conventional PTO clutch. The one way clutch assembly is compact. The barrel constitutes the wedge profile while all other auxiliary functions including the housing of the springs and rolling elements are housed within the plastic cage. There are no loose components. The roller type barrel constitutes an optimum strut angle and including angle, that ensures there is high torque carrying capacity. The simple single rated compression spring ensures the needed force to keep the roller in place. The plastic housing has an opening which works as a self-sludge removable feature. The endplates ensure the plastic housing along with its components do not engage in the relative axial movement. The splined shaft enables accommodation of axial play especially from the PTO shaft.

[0027] The key feature of the overrunning PTO shaft is that it keeps running on its inertia without transmitting the torque back into the input shaft. Another main feature of the overrunning PTO shaft is that it is compact and assembled within the gear box. This helps the overrunning PTO shaft to be lubricated by the oil inside the gear box, keeps it safe from external contamination and dirt, thus giving it a longer life. [001] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[002] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

Claims

We Claim:

1. A one-way overrunning power take-off (PTO) clutch (100) to restrict transmission of inertial force, the overrunning PTO clutch (100) comprising: a case barrel (105) comprising an inner wedge profile; and a plastic cage (110) configured to fit inside the barrel (105), wherein the plastic cage (110) comprises a plurality of springs (115) and rolling elements (120), wherein the springs (115) provides the required force to keep the rolling elements (120) in place.

2. The overrunning PTO clutch (100) as claimed in claim 1, wherein the overrunning PTO clutch (100) is fixed between an input shaft and a PTO shaft.

3. The overrunning PTO clutch (100) as claimed in claim 2, wherein the overrunning PTO clutch (100) when engaged allows the PTO shaft to keep running without transmitting torque back into the input shaft.

4. The overrunning PTO clutch (100) as claimed in claim 1, wherein the overrunning PTO clutch (100) is constituted inside a gear box.

5. The overrunning PTO clutch (100) as claimed in claim 1, wherein the plastic cage (110) has an opening to expel sludge.

6. The overrunning PTO clutch (100) as claimed in claim 1, wherein, at an input end of the overrunning PTO clutch (100), a flange (130) accommodating an input shaft is fastened on to the case barrel (105).

7. The overrunning PTO clutch (100) as claimed in claim 6, wherein an input lock plate (135) is fastened between the flange (130) and the barrel (105), wherein the flange (130) comprises a bush (140) to guide the input shaft.

8. The overrunning PTO clutch (100) as claimed in claim 7, wherein, at output end of the overrunning PTO clutch (100), the PTO shaft is coupled to a ring shaft (125), wherein the outer surface of the ring shaft (125) acts as the raceway for the rolling elements (120).

9. The overrunning PTO clutch (100) as claimed in claim 8, wherein an output lock plate (145) is slidingly fit over the ring shaft (125) and is fastened using a circlip (150).

10. The overrunning PTO clutch (100) as claimed in claim 9, wherein, the splined input and

PTO shafts enable axial motion, and the staked up clearance between the circlips (150, 155) accommodates axial play, and the input lock plate (135) and the output lock plate (145) ensures the plastic cage (110) and components housed inside the cage do not engage in relative axial movement.