1. Field of the Disclosure
The present disclosure is directed to gear train devices, and more particularly, a locking device to engage and disengage elements of the transmission while under load and/or without the need for a clutch.
2. Description of Related Art
Known power transmission gear trains often include a locking device to change the speed or direction of rotation of particular components of the gear train. Many of the locking devices require significant force to engage or disengage the locking device. This is particularly true of locking devices that include “in-out” or “up-down” designs which require either significant force to disengage the locking device or even an elimination of the rotational load on the gear train in order to disengage the locking device. The same degree of difficulty of disengaging the locking device can be exhibited in known rotating pawl designs that interact with cooperating shapes on gears and/or shafts.
Therefore, there exists a need for a locking device that can be selectively placed into and out of an engaged position with relative ease and may enable engagement/disengagement while a load is applied to the gear train, and even while the gear train is moving (e.g., rotating).
The following presents a simplified summary in order to provide a basic understanding of some example aspects of the disclosure. This summary is not an extensive overview. Moreover, this summary is not intended to identify critical elements of the disclosure nor delineate the scope of the disclosure. The sole purpose of the summary is to present some concepts in simplified form as a prelude to the more detailed description that is presented later.
According to one aspect of the subject application, a gear train locking device is provided. The gear train locking device includes a plurality of gears. The gears include teeth such that the teeth from one of the plurality of gears engages the teeth from another of the plurality of the gears in order to transmit rotational motion from one of the plurality of gears to another of the plurality of the gears. The gear train locking device also includes a plurality of shafts. The shafts are connected to the gears for transmitting rotational motion. The gear train locking device further includes a locking shaft having an outside diameter and a shaft axis. The locking shaft rotates about the shaft axis. Rotation of the locking shaft selectively moves the locking shaft between an engaged position and a disengaged position. The engaged position places the outside diameter of the locking shaft into engagement with one of the gears or the shafts to provide a physical interference between the locking shaft and the gear or the shaft to change the rotational motion of at least one of the gears or the shafts.
According to another aspect of the subject application, a planetary gear device having a central axis is provided and includes a stationary member. The planetary gear device also includes an input device. The input device is configured to rotate. The planetary gear device further includes a sun gear connected to the input device such that rotation of the input device rotates the sun gear. The sun gear defines an aperture. The planetary gear device still further includes a plurality of planet gears engaged with the sun gear. The planetary gear device also includes a ring gear. The ring gear is engaged with the planet gears. The planetary gear device further includes a carrier operably connected to the planet gears such that revolution of the planet gears relative to the sun gear rotates the carrier about the central axis. The planetary gear device still further includes an output shaft connected to the carrier. The output shaft is concentric with the central axis and extends through the aperture in the sun gear. The planetary gear device also includes a locking shaft mounted to the stationary member. The locking shaft has an outside diameter and a shaft axis. The locking shaft rotates about the shaft axis to selectively move the locking shaft between an engaged position and a disengaged position. The engaged position places the outside diameter of the locking shaft into engagement with the ring gear to create a physical interference preventing rotation of the ring gear relative to the stationary member such that rotation of the input device causes rotation of the output shaft.
According to yet another aspect of the subject application, a transmission locking device is provided. The transmission locking device includes a plurality of gears. The transmission locking device also includes a plurality of shafts. The shafts are connected to the gears for transmitting rotational motion. The transmission locking device further includes a locking shaft having an outside diameter and a shaft axis. The locking shaft rotates about the shaft axis. Rotation of the locking shaft selectively moves the locking shaft between an engaged position and a disengaged position. The locking shaft is configured to be engaged or disengaged with one of the gears or one of the shafts without the need for an associated clutch.
According to still yet another aspect, the subject application provides an epicyclical gear train including a stationary member. The epicyclical gear train also includes a plurality of planetary gear sets. Each planetary gear set includes an input device configured to rotate and a sun gear connected to the input device such that rotation of the input device rotates the sun gear. The sun gear defines an aperture. The planetary gear set also includes a plurality of planet gears engaged with the sun gear. The planetary gear set further includes a ring gear that is engaged with the planet gears. The planetary gear set still further includes a carrier operably connected to the planet gears such that revolution of the planet gears relative to the sun gear rotates the carrier about the central axis. The planetary gear set also includes an output connected to the carrier. The epicyclical gear train further includes a locking shaft mounted to the stationary member. The locking shaft has an outside diameter and a shaft axis and is configured to rotate about the shaft axis to selectively move the locking shaft between an engaged position and a disengaged position. The engaged position places the outside diameter of the locking shaft into engagement with at least one of the ring gears. This position creates a physical interference preventing rotation of at least one of the ring gears relative to the stationary member such that rotation of the input device causes change in the rotation of the output.
Advantages of the present disclosure will become more apparent to those skilled in the art from the following description of the embodiments of the disclosure which have been shown and described by way of illustration. As will be realized, the described apparatus and methods are capable of other and different embodiments, and their details are capable of modification in various respects.
These and other features of the present disclosure, and their advantages, are illustrated specifically in embodiments of the apparatus and methods now to be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
It should be noted that all of the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these figures may have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive.
Referring to
The frame 14 is a substantially rigid combination of members attached to each other to provide a solid base to which the components of the vertical tine tiller 10 can be attached. The vertical tine tiller 10 includes a pair of wheels 16 rotatably connected to the frame 14, as shown in
The operator control assembly 18 of the exemplary embodiment, shown in
The illustrated embodiment of the operator control assembly 18 also includes a wheel engagement lever 28 located within easy reach of the grip 24, as shown in
The operator control assembly 18, shown in
In the exemplary embodiment of the vertical tine tiller 10 shown in
Turning to
Turning to
The planetary gear set 104 also includes a plurality of shafts that are connected to the gears for transmitting rotational motion. The gears can serve several functions including reducing speed and power of the rotational motion from shaft to shaft, altering the direction of the rotational motion from shaft to shaft, etc. In the shown example, the shafts can include the previously mentioned driveshaft 52, a plurality of planet gear shafts 118, and a wheel axle 48. Of course, other examples of transmission assemblies may include any number of shafts.
At least one of the gears and/or shafts defines a plurality of cavities 120. As shown in
The transmission assembly 19 also includes a locking shaft 126 having an outside diameter 128 and a shaft axis 130. The locking shaft 126 rotates about the shaft axis 130, and this rotation selectively moves said locking shaft 126 between an engaged position shown in
As such, the engaged position of the locking shaft 126 creates a physical interference to change the rotational motion of at least one of the gears or the shafts such as preventing rotational motion of the ring gear 110 relative to the locking shaft 126 and any other fixed point on the transmission assembly 19. Additionally, the disengaged position of the locking shaft 126 removes the described physical interference and enables the ring gear 110 to rotate relative to the locking shaft 126 or another of the gears.
As can be seen, the engaged position places the outside diameter 128 of the locking shaft 126 into engagement with one of the gears or the shafts (e.g. the ring gear 110). In this example, the locking shaft 126 rotates into and out of the engaged position through sliding contact with the curved surface 122 of the ring gear 110. The described arrangement of the locking shaft 126 and its partially circular cross-section 134 cooperating with the curved surface 122 of the cavity 120 can provide the benefit of significantly reducing the force required to engage or disengage the locking mechanism. This is particularly true while the transmission assembly 19 is under load. For example, previously known devices can include “in-out” or “up-down” designs which require either significant force to disengage the locking mechanism or even an elimination of the rotational load on the gear train in order to disengage the locking mechanism. The same degree of difficulty in operation can be true of known rotating pawl designs that interact with cooperating shapes on gears and/or shafts. However, the described locking shaft 126 can be rotated into and out of the engaged position with the ring gear 110 under load and even when the ring gear 110 is rotating. As such, the gear train locking device 100 does not require a clutch.
In one example, the locking shaft 126 is manually rotated into and out of the engaged position by an associated operator (e.g, by using the wheel engagement lever 28). In another example, the locking shaft 126 is operably connected to a controller (not shown) located on a powered lawn device, such as the example device shown in
The following will serve as a description of the operation of an exemplary transmission assembly 19 as illustrated in the figures. The locking shaft 126 is in the disengaged position as shown in
Rotation of the sun gear 106 causes rotation of the plurality of planet gears 108 which urge rotation of the ring gear 110. The plurality of planet gears 108 rotate about their respective planet gear shafts 118, but do not cause rotation of the planet gear carrier 104. In one example, the lack of rotational motion of the planet gear carrier 104 is due to the resistance provided by bearings, seals, and the ground contact of the wheels. As such, all of the transmission assembly 19 output corresponds to the rotation of the ring gear 110. As a result, even though the transmission assembly 19 and the driveshaft 52 are in continuous engagement, the wheel axle 106 does not turn when the locking shaft 126 is in the disengaged position. In another example, a wheel or axle brake may be employed with this apparatus, but it is not necessary.
As the operator decides to engage the drive wheels of the device, the operator can urge a device (not shown) such as a lever to urge rotation of the locking shaft 126. The locking shaft 126 then rotates from the disengaged position shown in
In the engaged position, physical interference prevents the output of the transmission assembly 19 from rotating the ring gear 110. As such, the fixed ring gear 110 causes rotation of the planet gear shafts 118 relative to the sun gear 106, causing rotation of the planet gear carrier 104. The planet gear carrier 104 is attached to the wheel axle 48 and rotation of the planet gear carrier 104 causes rotation of the wheel axle 48. This rotation, in turn, overcomes the resistance of the bearings, seals, and the ground contact of the wheels and causes rotation of the wheels to drive the powered lawn device.
When the operator chooses to disengage the drive again, he or she can manually urge rotation of the locking shaft 126 to the disengaged position. Even as the ring gear 110 is under a rotational load condition or even while rotating, rotation of the locking shaft 126 is relatively easy, as the D-shaped cross-section 134 rotates in sliding engagement with the curved surface 122, enabling disengagement of the locking shaft 126 with relatively little force required. Additionally, the described apparatus and methods enable the use of a gear train locking device (e.g., a transmission locking device) that can engage gears or shafts of the gear train, transmission, epicyclic drive, etc. without using a clutch. Additionally, the described apparatus and methods enable the use of a gear train locking device to engage elements of the gear train, transmission, epicyclic drive, etc. without using a clutch while the elements to be engaged are under load and/or are rotating.
The driveshaft 52 is an elongated shaft that is rotatable relative to the transfer casing 40. At least a portion of the driveshaft 52 extends forwardly from the transfer casing 40 to allow the driveshaft to be operatively connected to the power source 12. In an embodiment, a first end of the driveshaft 52 is driven by a belt-and-pulley connection with the rotational output of the power source 12, which provides for an indirect rotational transfer to the driveshaft 52 from the power source 12. In another embodiment, the first end of the driveshaft 52 is coupled to the crankshaft (not shown) of the power source 12 for direct rotational transfer to the driveshaft 52. The driveshaft 52 is substantially horizontally aligned within the transfer casing 40. The driveshaft 52 is configured to rotate about is longitudinal axis, which is similarly horizontally oriented. The driveshaft 52 is positively positioned within the transfer casing 40 by way of bearings adjacent to the forward end of the transfer casing (in the transmission housing 42) as well as adjacent to the rearward end (in the power head housing 46). In an embodiment, the driveshaft 52 engages the transmission assembly 19 via worm gear that is formed into the outer circumferential surface of the driveshaft 52. The worm gear connection on the driveshaft 52 (
In operation, the power source 12 produces a rotational output, which is transferred to the driveshaft 52, thereby causing the driveshaft 52 to rotate about the longitudinal axis thereof. As the driveshaft 52 rotates, the transfer gear 54 coupled to the driveshaft 52 rotates in a similar manner. The driveshaft 52 also selectively drives the transmission assembly 19 that is operatively coupled to the driveshaft 52.
Turning to
As shown in
The epicyclical gear train 200 further includes a stationary member, one example of which is the transmission housing 42, however any suitable stationary object will suffice. A locking shaft 228 is mounted to the stationary member and includes an outside diameter 230 and a shaft axis 234. The locking shaft 228 is configured to rotate about the shaft axis 234 to selectively move the locking shaft 228 between an engaged position and a disengaged position. The engaged position places the outside diameter 230 of the locking shaft 228 into engagement with at least one of the ring gears 218 to create a physical interference preventing rotation of at least one of the ring gears 218 relative to the stationary member. This engagement enables rotation of the input device 214 to cause change in the rotation of the output 226.
As with the first embodiment, the epicyclical gear train 200, can include ring gears 218 that define a plurality of cavities 236. Each of the cavities 236 has a curved surface 238 and the locking shaft 228 rotates into and out of the engaged position through sliding contact with the curved surface 238 of at least one of the ring gears 216.
As shown in
One having skill in the art will understand that differing planet gear 216 arrangements can produce various gear reductions to produce desired forward and reverse speeds for the lawn implement or other power driven device. For example, using the planetary gear sets 204, 206 as shown in
It is also to be appreciated that the present disclosed apparatus can be used to shift between forward and reverse gears in a transmission. Because of the rotational motion of the locking shaft 228 and the sliding contact with the cavities 236, this shift can be achieved with relatively low force. Furthermore, the transmission can be shifted between forward and reverse gears without a clutch and while the transmission is under load.
While preferred embodiments of the present disclosure have been described, it should be understood that the present disclosure is not so limited and modifications may be made without departing from the present disclosure. The scope of the present invention is defined by the appended claims, and all devices, processes, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.
The application claims the benefit of U.S. Provisional Application No. 62/106,539, filed Jan. 22, 2015, the entire disclosure of which is hereby incorporated herein by reference.
Number | Date | Country | |
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62106539 | Jan 2015 | US |