Source: https://www.allindianpatents.com/patents/253753-neutral-hold-device-for-hydrostatic-continuously-variable-speed-change-device
Timestamp: 2020-07-03 10:08:57
Document Index: 96963563

Matched Legal Cases: ['art 7', 'art 21', 'art 21', 'arts 21', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30']

Indian Patents. 253753:NEUTRAL HOLD DEVICE FOR HYDROSTATIC CONTINUOUSLY VARIABLE SPEED CHANGE DEVICE
NEUTRAL HOLD DEVICE FOR HYDROSTATIC CONTINUOUSLY VARIABLE SPEED CHANGE DEVICE BACKGROUND OF THE INVENTION
The present invention relates to a neutral hold device for a hydrostatic continuously variable speed change device,
In other words, reduction of the spring force due to changes that occur over time, increased viscosity of the hydraulic oil due to decreased ambient temperature, and other effects can lead to drawbacks whereby the neutral state of the hydrostatic continuously variable speed change device is no longer obtained. Increasing the urging force of the spring is one method of preventing this drawback, but the speed change operation of the hydrostatic
continuously variable speed change device against the urging of the spring
becomes too stiff in this case. Drawbacks therefore occur in that the
operability of the hydrostatic continuously variable speed change device is
According to this characteristic configuration, the auxiliary urging force of the auxihary urging means acts on the trunnion shaft while the trunnion shaft is positioned in the proximate region of the pre-set neutral position. Therefore, the urging force of the spring and the auxiliary urging force of the auxiliary urging means act on the trunnion shaft.
While the trunnion shaft is not positioned in the proximate region of the pre-set neutral position, e.g., while the trunnion shaft is positioned in a region farther from the neutral position than the proximate region, the auxihary urging force of the auxihary urging means does not act on the trunnion shaft, and therefore only the urging force of the spring acts on the trunnion shaft.
In other words, the urging force for urging the trunnion shaft toward the neutral position can be strengthened by the action of the auxihary urging force only while the trunnion shaft is positioned in the proximate region of the pre-set neutral position.
Through this configuration, when the operation of the speed shifter is withdrawn, even when reduction of the urging force of the spring due to use and passage of time, increased viscosity of the hydraulic oil due to reduced
ambient temperature, and other effects make it difficult to return the trunnion shaft to the neutral position merely by the urging force of the spring, the auxiliary urging force of the auxiliary urging means acts as an urging force for returning the trunnion shaft to the neutral position when the trunnion shaft has been returned to the proximate region of the neutral position by the urging force of the spring. As a result, the trunnion shaft can be reliably returned to the neutral position regardless of reduction of the urging force of the spring due to use and passage of time, increased viscosity of the hydraulic oil due to reduced ambient temperature, and other effects.
Since the auxiliary urging force of the auxiliary urging means acts on the trunnion shaft only while the trunnion shaft is positioned in the proximate region of the pre-set neutral position, the speed change operation of the hydrostatic continuously variable speed change device is stiffened by the auxiliary urging force of the auxiliary urging means for a short time when the trunnion shaft is positioned in the proximate region of the pre-set neutral position, but the stiffening of the speed change operation of the hydrostatic continuously variable speed change device due to the auxiliary urging force of the auxiliary urging means can be prevented from occurring while the trunnion shaft is outside of the proximate region of the neutral position.
In an aspect of the present invention, the auxiliary urging means has an auxiliary cam formed in the second member; a contacting member for coming in contact with the auxiliary cam; and an auxiliary spring for urging
the contacting member toward the auxiliary cam; and the auxiliary cam is formed such that the auxiliary urging force is generated from an urging force of the auxiliary spring while the trunnion shaft is positioned in the proximate region, and the auxiliary urging force is not generated from the urging force of the auxiliary spring while the trunnion shaft is not positioned in the proximate region.
According to this configuration, when the auxiliary urging force of the auxiliary urging means decreases due to the passage of time or other effects, the auxiUary urging force can be adjusted to the appropriate size by the adjusting means.
FIG. 6 is an exploded perspective view showing the relevant parts of the
structure of the neutral hold device and the auxiliary urging means;
FIG. 9 is a longitudinal sectional side view showing the relevant parts in the operation of the auxihary urging means when the trunnion shaft is in the separated region. DESCRIPTION OF THE PREFERRED EMBODIMENTS
The rear part of the transmission case 9 is provided with a pair of left and right lift arms 10 that pivot up and down by the action of a hydraulic cylinder (not shown) provided inside the transmission case 9; a power takeoff shaft 11 for enabling the power from the engine 3 to be taken off to the outside; and other components. A rotary cultivator, a plow, or another
implement can thereby be coupled to the rear part of the tractor so as to be able to be driven, raised, and lowered. The tractor is also configured so that power can be transmitted to a rotary cultivator or other drivable implement.
The neutral hold device 2 is provided with a first member 13 that rotates integrally with the trunnion shaft 12, a second member 14 provided immediately in front of the first member so as to be able to pivot forward and backward, a spring 15 for pivotally urging the second member 14 toward the first member 13 to the rear, and other components. A tension spring is employed as the spring 15,
The support shaft 16 is connected by a bolt 19 to a bracket 20 provided to the HST 1, so that a center shaft 16a of the support shaft 16 can change position about the bolt 19. Through this configuration, when the cam
follower 17 is positioned at the bottom of the cam C, the set position of the support shaft 16 as the pivotal support of the second member 14 can easily be changed so as to place the trunnion shaft 12 in the neutral position N.
As shown in FIGS. 1, 2, and 5, the first member 13 is linked via a linking mechanism 22 to a speed change pedal 21 provided to the right side of the riding and operating part 7. The speed change pedal 21 is provided with a front pedal operating part 21A for forward speed change, and a rear pedal operating part 21B for reverse speed change, and the speed change pedal 21 is pivoted in the manner of a balance about a left-right oriented support shaft 23 as a pivot support by the depression of the pedal operating parts 21A, 21B and the action of the neutral hold device 2.
As shown in FIGS. 2 through 9, a circular cam hole 30 having the center 14a of the boss 14A at the center thereof is formed in the second member 14, One end 31A of a rod 31 that is curved in a U shape is engaged in the cam hole 30, The rod 31 is supported by the bracket 20 so as to pivot vertically about the other end 31B thereof as a left-right-oriented support shaft. One end of an auxiliary spring 32 for pivotally urging the rod 31 downward is hooked to one end 31A of the rod 31. A tension spring is employed as the auxiliary spring 32. The other end of the auxiliary spring 32 is connected to the bracket 20 via an adjusting means 33.
A tilted part 30a that is tilted upward and to the rear at a prescribed angle, and a circular part 30b having the center 14a of the boss 14A at the center thereof are formed in sequence in the front-rear direction in the lower edge 30A of the cam hole 30,
The tilted part 30a is formed in a prescribed position of the lower edge 30A so as to be pressed by one end 31A of the rod 31 by the urging of the auxiliary spring 32 when the trunnion shaft 12 is positioned in the neutral position N and the proximate region Al of the pre-set neutral position N (see FIGS. 3, 7, and 8). The circular part 30b is formed at the rear part of the lower edge 30A so that one end 31A of the rod 31 is pressed by the urging of the auxiliary spring 32 when the trunnion shaft 12 is positioned in a separated region A2 that is farther from the neutral position N than the proximate region Al (see FIGS. 4 and 9).
According to the configuration described above, while the trunnion shaft 12 is in the neutral position N, the one end 31A of the rod 31 makes contact with the tilted part 30a through the urging of the auxiliary spring 32 and pushes the second member 14 toward the first member 13. The second member 14 therefore receives the urging force of the auxiliary spring 32 and the urging force of the spring 15, and the cam follower 17 is maintained in position at the bottom of the cam C, In other words, while the trunnion shaft 12 is in the neutral position N, the urging force of the spring 15 and the urging force of the auxiliary spring 32 act on the trunnion shaft 12 as retaining forces that retain the trunnion shaft 12 in the neutral position N (see FIGS. 3 and 7).
The one end 31A of the rod 31 also makes contact with the tilted pai't 30a through the urging of the auxiliary spring 32, and pushes the second member 14 toward the first member 13 when the trunnion shaft 12 is positioned in the proximate region Al. The second member 14 therefore
receives the urging force of the auxiliary spring 32 and the urging force of the spring 15 at this time, and the cam follower 17 pivots toward the first member
13	so as to face the bottom of the cam C. The first member 13 integrally
rotates toward the neutral position N along with the trunnion shaft 12 in
conjunction with the pivoting of the second member 14. In other words, while
the trunnion shaft 12 is positioned in the proximate region Al, the urging
force of the spring 15 and the urging force of the auxiliary spring 32 act on the
trunnion shaft 12 as urging forces that urge the trunnion shaft 12 toward the
neutral position N (see FIG. 8).
While the trunnion shaft 12 is positioned in the separated region A2, the one end 31A of the rod 31 makes contact with the circular part 30b through the urging of the auxiliary spring 32 and pushes the second member
14	toward the center 14a of the boss 14A. Therefore, the second member 14
is not pivoted by the urging force of the auxiliary spring 32 at this time, and
the cam follower 17 also does not face toward the bottom of the cam C. In
other words, while the trunnion shaft 12 is positioned in the separated region
A2, only the urging force of the spring 15 acts on the trunnion shaft 12 as an
urging force that urges the trunnion shaft 12 toward the neutral position N
(see FIGS. 4 and 9).
In short, in the configuration described above, the auxiliary spring 32, the rod 31, and the lower edge 30A of the cam hole 30 constitute an auxiliary urging means 34 that generates an auxiliary retaining force for retaining the trunnion shaft 12 in the neutral position N from the urging force of the auxiliary spring 32 to increase the retaining force for retaining the trunnion shaft 12 in the neutral position N while the trunnion shaft 12 is in the neutral position N, and that generates an auxiliary urging force for urging the trunnion shaft 12 toward the neutral position N from the urging force of the auxiliary spring 32 and increases the urging force for urging the trunnion shaft 12 toward the neutral position N while the trunnion shaft 12 is in the proximate region Al,
The lower edge 30A of the cam hole 30 functions as an auxiliary cam Ca for generating an auxihary retaining force from the urging force of the auxiliary spring 32 while the trunnion shaft 12 is in the neutral position N, generating an auxiliary urging force from the urging force of the auxiliary spring 32 while the trunnion shaft 12 is positioned in the proximate region Al, and acting so as not to generate an auxiliary urging force from the urging
force of the auxiliary spring 32 while the trunnion shaft 12 is positioned in the separated region A2.
Through this configuration, when the operation of the speed change pedal 21 is withdrawn, even when reduction of the urging force of the spring 15 due to use and passage of time, increased viscosity of the hydraulic oil due to reduced ambient temperature, and other effects make it difficult to return the trunnion shaft 12 to the neutral position N merely by the urging force of the spring 15, the urging force of the auxiliary spring 32 is applied to the trunnion shaft 12 that has been returned to the proximate region Al by the urging force of the spring 15. As a result, the trunnion shaft 12 can be reliably returned to the neutral position N regardless of reduction of the urging force of the spring 15 due to passage of time, increased viscosity of the hydraulic oil of the HST 1 due to reduced ambient temperature, and other effects.
The urging force of the auxiliary spring 32 acts on the trunnion shaft 12 only while the trunnion shaft 12 is positioned in the neutral position N and the proximate region Al. Therefore, the speed change operation of the HST 1 is stiffened by the urging force of the auxiliary spring 32 during the initial period of the speed change from the neutral position N, in which the trunnion shaft 12 is positioned in the proximate region Al, to the separated region A2, but the stiffening of the speed change operation of the HST 1 due to the urging force of the auxiliary spring 32 can be prevented from occurring while the trunnion shaft 12 is positioned in the separated region A2,
(1)	The neutral hold device 2 of the hydrostatic continuously variable speed change device 1 according to the present invention may be applied to a rice planting machine, a combine, or other vehicle that is provided with a hydrostatic continuously variable speed change device 1.
(2)	The neutral hold device may have a cam member that rotates integrally with the trunnion shaft 12 and is provided with an auxiliary cam Ca shaped as a fan shaped and indented in a V shape on the external periphery thereof, a contacting member B for coming in contact with the cam member, and an auxiliary spring 32 for urging the contacting member B into contact with the cam member. An auxiliary urging means 34 may be composed of the auxiliary cam Ca of the cam member, the contacting member B, and the auxiliary spring 32, and may be set so that in the period in which the trunnion shaft 12 is positioned in the proximate region Al, the contacting member B makes contact with the auxiliary cam Ca, whereby the urging force of the auxiliary spring 32 functions as an auxiliary urging force for urging the trunnion shaft 12 toward the neutral position N, and so that in the period in which the trunnion shaft 12 is positioned in the separated region A2, the contacting member B does not make contact with the axixiliary Ca, whereby the urging force of the auxiliary spring 32 does not function as an auxiliary urging force for urging the trunnion shaft 12 toward the neutral position N.
(3)	In another possible configuration, the neutral hold device has a cam member that pivots integrally with the second member 14 about the support shaft 16 and is provided with an auxiliary cam Ca formed so that a tilted part that is tilted upward and to the rear at a prescribed angle, and a circular part centered on the center shaft 16a of the support shaft 16, are formed in sequence in the front-rear direction. The device also has a contacting member B for coming in contact with the cam member, and an auxiliary spring 32 for urging the contacting member B into contact with the cam member. An auxiliary urging means 34 is composed of the auxiliary cam Ca of the cam member, the contacting member B, and the auxiliary spring 32,
and is set so that in the period in which the trunnion shaft 12 is positioned in the proximate region Al, the contacting member B makes contact with the tilted part of the auxihary cam Ca, whereby an auxiliary urging force for urging the trunnion shaft 12 toward the neutral position N is generated from the urging force of the auxihary spring 32, and so that in the period in which the trunnion shaft 12 is positioned in the separated region A2, the contacting member B makes contact with the circular part of the auxiliary cam Ca, whereby an auxiliary urging force is not generated from the urging force of the auxiliary spring 32.
(4)	A tilted part 30a that is tilted upward and to the rear at a prescribed angle, and a circular part 30b centered on the center 14a of the boss 14A may be formed in sequence in the front-rear direction in the outer edge of the second member 14, and an auxihary cam Ca may be provided to the second member 14.
(5)	A cam member in which a tilted part 30a that is tilted upward and to the rear at a prescribed angle, and a circular part 30b centered on the center 14a of the boss 14A are formed in sequence in the front-rear direction may be attached to the second member 14.
(6)	The auxihary urging means 34 may be set so that, for example, one end 31A of the rod 31 is brought into contact with the bottom edge of the front end of a cam hole 30 by the urging of the auxiliary spring 32 while the trunnion shaft 12 is in the neutral position N, and the second member 14 is pushed toward the center 14a of the boss 14A, whereby only the urging force of the spring 15 acts on the trunnion shaft 12 as a retaining force for retaining the trunnion shaft 12 in the neutral position N.
(7)	Compression springs, helical springs, or the like may be employed as the spring 15 and the auxiliary spring 32,
(8)	Various modifications of the proximate region Al of the neutral position N are possible according to the type, urging force, and other characteristics of the employed spring 15.
(9)	The adjusting means 33 may be composed of a rod engaged at one end thereof with the other end of the auxiliary spring 32; a locking pin removably inserted in the other end of the rod; and a plurality of washers that can be installed between the locking pin and the bracket 20, wherein the urging force of the auxiliary spring 32 can be adjusted by changing the number of washers installed between the locking pin and the bracket 20.
1.	A neutral hold device for a hydrostatic continuously variable
speed change device having a trunnion shaft, comprising:
a spring for urging said cam follower against said cam so that said trunnion shaft is retained in a neutral position by said cam follower being positioned in a set position of said cam by the urging of said spring;
auxiliary urging means for generating an auxiliary urging force for urging said trunnion shaft toward said neutral position while said trunnion shaft is positioned in a proximate region of said neutral position set in advance.
said auxiliary urging means is configured so as to generate said auxiliary urging force by pivotally urging said second member so that said cam follower is urged toward said set position of said cam while said trunnion shaft is positioned in said proximate region.
3.	The device according to claim 1 or 2 wherein
said auxiliary urging means has an auxiliary cam formed in said second member; a contacting member for coming in contact with the auxiliary cam; and an auxiliary spring for urging the contacting member toward said auxiliary cam; and
said auxiliary cam is formed such that said auxiliary urging force is generated from an urging force of said auxiliary spring while said trunnion shaft is positioned in said proximate region, and said auxiliary urging force is not generated from the urging force of said auxiliary spring while said trunnion shaft is not positioned in said proximate region.
4.	The device according to one of claims 1 to 3, comprising
adjustable means for adjusting said auxiliary urging force.
704-CHE-2008 ENGLISH TRANSLATION 09-02-2012.pdf
704-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 25-09-2012.pdf
704-CHE-2008 AMENDED CLAIMS 13-07-2012.pdf
704-CHE-2008 CORRESPONDENCE OTHERS 09-02-2012.pdf
704-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 13-07-2012.pdf
704-CHE-2008 FORM-3 13-07-2012.pdf
704-CHE-2008 OTHER PATENT DOCUMENT 13-07-2012.pdf
704-che-2008-abstract.pdf
704-che-2008-claims.pdf
704-che-2008-correspondnece-others.pdf
704-che-2008-description(complete).pdf
704-che-2008-drawings.pdf
704-che-2008-form 1.pdf
704-che-2008-form 18.pdf
704-che-2008-form 26.pdf
704-che-2008-form 3.pdf
704-che-2008-form 5.pdf
704/CHE/2008
2-47, SHIKITSUHIGASHI 1-CHOME NANIWA-KU, OSAKA-SHI, OSAKA 556-8601
1 NISHINO, AKIFUMI C/O KUBOTA CORPORATION SAKAI SEIZOSHO, 64,ISHIZUKITAMACHI SAKAI-KU, SAKAI-SHI OSAKA 590-0823
1 2007-212348 2007-08-16 Japan