KR101771237B1 - Fork shaft assembly for intermediate transmission - Google Patents

Abstract

The present invention is characterized in that at least one shift fork is provided so as to be reciprocatable along the axial direction of the fork shaft and the shift fork is connected to a sleeve for varying the gear ratio selectively between a plurality of gears coupled to the engine drive shaft A fork shaft assembly for a transmission, comprising: a fork shaft control portion disposed on one end coaxial along a longitudinal direction of the fork shaft, wherein the fork shaft control portion includes a case, a part of the fork shaft inserted into the case A first piston reciprocating along the axial direction and integrally coupled to the fork shaft to define an interior of the case; a first piston spaced a predetermined distance along the axial direction of the fork shaft from the first piston, A second piston formed to surround the first piston and a second piston formed at one end of the second piston And a third piston reciprocally moving along the axial direction of the fork shaft, wherein a coupling groove is formed radially inwardly on an outer peripheral surface of each of the first piston, the second piston, and the third piston, A fork shaft assembly for an intermediate transmission in which a sealing assembly is provided in each engagement groove.

Description

[0001] FORK SHAFT ASSEMBLY FOR INTERMEDIATE TRANSMISSION FOR INTERMEDIATE TRANSMISSION [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fork shaft assembly for an intermediate transmission, and more particularly to an intermediate transmission fork shaft assembly having a sealing assembly inside a fork shaft control portion for supporting one end of the fork shaft.

Generally, the intermediate transmission is a device that distributes the power by distributing the front and rear axle power and is mounted on the equipment that travels or works on rough roads and underground.

The intermediate transmission is provided between the front and rear axles, and is an auxiliary transmission device capable of maintaining an appropriate shift running state by appropriately selecting a gear ratio according to the running state of the road surface.

For example, the intermediate transmission may be provided to enable three-speed shifting of neutral, low-speed, and high-speed stages. In addition, the intermediate transmission may be selectively switched according to the driving state to reduce the burden on vehicles and equipment, Speed and driving force can be controlled.

The intermediate transmission has a structure in which an input shaft and an output shaft are disposed inside a transmission case and a plurality of friction elements are disposed on the outer circumference of the transmission case, which is selectively operated to perform a shifting operation. Generally, selective operation is performed by pneumatic or manual shifting.

The intermediate transmission includes a structure in which at least one shift fork is coupled to the fork shaft so as to be reciprocally movable along the axial direction of the fork shaft.

In addition, a pair of gear portions disposed coaxially with a driving shaft supplied with an engine driving force are provided, and a sleeve is reciprocally movable in a pair of gear portions. The sleeve is mounted on a fork, which is moved integrally with the fork shaft And is moved to the gripped state.

The shift fork is controlled to be reciprocated by a fork shaft actuator disposed at one end of the fork shaft, and a fork shaft guide member is disposed at the other end of the fork shaft. At this time, the sealing member provided on the outer circumferential surface of the piston reciprocally moved together with the fork shaft in the fork shaft guide member is worn and malfunctions during control of the hydraulic pressure due to a reduction in the sealing function.

United States Patent 9,279,494 (2016.03.08)

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an intermediate transmission capable of securing durability and maintaining a sealing function even if wear is generated in a sealing member provided on the outer circumferential surface of a piston reciprocally moved together with the fork shaft in a fork shaft guide member And a fork shaft assembly for a fork shaft.

The present invention has been made in view of the above problems, and it is an object of the present invention to at least solve the problems in the conventional arts which are well known to those skilled in the art.

According to an aspect of the present invention, there is provided an intermediate transmission fork shaft assembly including at least one shift fork capable of reciprocating along an axial direction of a fork shaft, the shift fork being coupled to an engine drive shaft A fork shaft assembly for an intermediate transmission connected to a sleeve for selectively varying a gear ratio among a plurality of gears, the fork shaft assembly including a fork shaft control portion disposed on one end coaxial along the longitudinal direction of the fork shaft, The control unit includes a case, a first piston which is inserted into the case and reciprocally moved along the axial direction, the first piston being integrally coupled to the fork shaft and partitioning the inside of the case, And a pair of upper and lower shafts A second piston which is formed so as to surround the end portion of the fork shaft and a third piston which is engaged with one end of the second piston and reciprocates along the axial direction of the fork shaft, The outer circumferential surface of each of the piston and the third piston has a coupling groove formed radially inward, and each of the coupling grooves may be provided with a sealing assembly.

The sealing assembly may include an inner ring and an outer ring formed to surround the outer circumferential surface of the inner ring.

The inner ring may be formed of NBR (nitrile-butadiene rubber), and the outer ring may be formed of Teflon.

The inner ring may have a circular cross-sectional shape.

A small diameter portion having a smaller diameter may be formed at an end of the fork shaft, and the second piston may be closely attached to surround the small diameter portion.

The first piston may be fixed to the second piston along the axial direction of the fork shaft to be reciprocally moved integrally therewith.

Wherein the second piston is slid in close contact with an inner circumferential surface of the third piston, a second piston protruding portion is formed radially outwardly on an outer circumferential surface of the end portion of the second piston so that the third piston, And can be locked by the jaws.

The details of other embodiments are included in the detailed description and drawings.

The embodiments of the present invention have at least the following effects.

That is, the fork shaft assembly for an intermediate transmission according to the embodiments of the present invention assures durability even when wear occurs on the sealing member provided on the outer circumferential surface of the piston reciprocally moved together with the fork shaft inside the fork shaft guide member, Function can be maintained.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a perspective view illustrating an intermediate transmission in a state where a fork shaft assembly according to an embodiment of the present invention is mounted.
2 is a perspective view illustrating a state in which the fork shaft assembly according to the embodiment of the present invention is separated from the intermediate transmission.
3 is a cross-sectional view of a fork shaft assembly in accordance with an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is to be understood that the terms comprise and / or comprise are used in a generic sense to refer to the presence or addition of one or more other elements, steps, operations and / or elements other than the stated elements, steps, operations and / It is used not to exclude. And "and / or" include each and any combination of one or more of the mentioned items.

Further, the embodiments described herein will be described with reference to cross-sectional views and / or schematic drawings that are ideal illustrations of the present invention. Thus, the shape of the illustrations may be modified by manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention are not limited to the specific forms shown, but also include changes in the shapes that are generated according to the manufacturing process. In addition, in the drawings of the present invention, each component may be somewhat enlarged or reduced in view of convenience of explanation. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings for explaining an fork shaft assembly for an intermediate transmission according to embodiments of the present invention.

FIG. 1 is a perspective view showing an intermediate transmission in a state where a fork shaft assembly according to an embodiment of the present invention is mounted, FIG. 2 is a perspective view showing a state in which the fork shaft assembly is separated from the intermediate transmission according to an embodiment of the present invention, 3 is a cross-sectional view of a fork shaft assembly according to an embodiment of the present invention.

1 to 3, the fork shaft assembly according to an embodiment of the present invention may be installed in an intermediate transmission 100 disposed between front and rear axles of a large-sized vehicle.

The fork shaft assembly includes at least one shift fork 140 reciprocally movable along the axial direction of the fork shaft 130 and the fork shaft 130. The shift fork 140 includes a plurality of gears (Not shown) for selectively implementing a plurality of gear ratios between the gears (not shown).

A fork shaft control unit 110 for controlling the shift fork 140 to selectively move along the axial direction of the fork shaft 130 is formed at one end of the fork shaft 130, The detent portion 200 may be formed to provide a sense of detent according to the stage.

The fork shaft control unit 110 includes a case 102 having an internal space and a part of the fork shaft 130 inserted into the case 102 and moving along the axial direction, A first piston 121 which is coupled to the inside of the case 102 and which surrounds the outer peripheral surface of the end portion of the fork shaft 130 by a predetermined distance along the axial direction of the fork shaft 130 from the first piston 121, And a third piston 123 which is engaged with one end of the second piston 122 and the second piston 122 which are formed so as to reciprocate along the axial direction of the fork shaft 130. [

The inner circumferential surface of the case 102 may be provided with a tightly coupled portion 103 which is held in close contact with the outer circumferential surface of the fork shaft 130. Here, a portion 102 of the fork shaft 130 is moved along the axial direction while being inserted into the case 102, and a case 102 (see FIG. 10) in which the inserted portion of the fork shaft 130 is disposed by the close- So that a predetermined pressure can be formed in the inner space.

The first piston 121 may be disposed at a position spaced a predetermined distance in the direction of the end of the fork shaft 130 from the contact portion 103. The first piston 121 may be formed to surround the outer circumferential surface of the small diameter portion 131. The small diameter portion 131 may be formed to have a small diameter at the end of the fork shaft 130. [

The first piston 121 is fixed to the small diameter portion 131 so that the first piston 121 can move integrally as the fork shaft 130 moves. Here, the space in which the first piston 121 reciprocates within the case 102 may be defined as the first chamber 112a. A hydraulic pressure may be formed in the first chamber 112a and the first chamber 112a may be connected to the first chamber 112a such that a working fluid for forming the pressure may be supplied from the outside to the first chamber 112a, 111a may be formed.

When the hydraulic pressure is supplied to the first pressure port 111a, a high pressure is generated in the first chamber 112a and the fork shaft 130 moves to the left in the state of FIG. 3, The end portion 131b comes into contact with the terminal 113a of the first sensor 113 to apply the speed change signal to the high speed or the low speed. The first sensor 113 may be applied to either the high-speed signal or the low-speed signal sensor depending on the arrangement of the plurality of gear trains located coaxially with the sleeve that the shift fork 140 moves.

The second piston 122 may be formed to fix the first piston 121 in the axial direction. The second piston 122 may be formed to have a length to cover the entire outer circumferential surface of the small diameter portion 131 and the second piston 122 may be fixed to the small diameter portion 131 to move along with the movement of the fork shaft 130 .

Here, the space in which the second piston 122 reciprocates within the case 102 may be defined as the second chamber 112b. The second chamber 112b may be formed with a hydraulic pressure and a second pressure port 111b may be formed to allow the working fluid for pressure formation to be supplied from the outside to the second chamber 112b as shown in FIG. .

When the hydraulic pressure is supplied to the second pressure port 111b, a high pressure is generated in the second chamber 112b and the fork shaft 130 is placed in the state shown in FIG. 3 so that the end 131b of the fork shaft 130 Is in a state of being separated from the terminal 113a of the operation sensor 113, it can be set to the neutral-end state of the intermediate transmission.

At the end of the second piston 122, a second piston step jaw 122a projecting radially outward can be formed.

The second piston stage jaw portion 122a moves in a direction in which the third piston 123 is moved away from the second piston 122 and is locked so as not to be separated from the second piston 122. [

A third piston inner protrusion 123a is formed on the inner circumferential surface of the third piston 123 so as to be closely attached to the outer circumferential surface of the second piston 122 to be engaged with the second piston stepped portion 122a .

A third piston stage jaw 123b protruding radially outward from the outer circumferential surface of the third piston inner protrusion 123a may be formed at the opposite end of the third piston inner protrusion 123a along the longitudinal direction of the third piston 123. [ The third piston stepped portion 123b is allowed to move in the axial direction in close contact with the inner circumferential surface of the case 102. [

Here, the space in which the third piston 123 reciprocates within the case 102 can be defined as the third chamber 112c. A hydraulic pressure may be formed in the third chamber 112c and a third pressure port 111c may be formed so that a working fluid for pressure formation may be supplied from the outside to the third chamber 112c as shown in FIG. .

When the hydraulic pressure is supplied to the third pressure port 111c, a high pressure is generated in the third chamber 112c and the fork shaft 130 moves to the right in the state of FIG. 3, (Not shown) of the second sensor 210 located in the second housing 200 to apply the speed change signal to the high speed or the low speed.

The second sensor 210 may be applied to the other of the sensors for high-speed signals or low-speed signals according to the arrangement of the plurality of gear trains coaxially disposed with the sleeve that the shift fork 140 moves.

The outer circumferential surface of the first piston 121 as described above has a coupling groove 121g radially inwardly and the sealing assembly 124 can be coupled to the coupling groove 121g.

The engaging grooves 121g are grooved to have diameters smaller than the diameters of the respective pistons so that each of the sealing assemblies 124 is seated securely.

The sealing assembly 124 may include an inner ring 124a and an outer ring 124b.

The inner ring 124a may be formed in a ring shape closely fitted to the coupling groove 121g and the outer ring 124b may be formed to have a larger diameter so as to be fixed to the outer peripheral surface of the inner ring 124a .

For example, NBR (nitrile-butadiene rubber) can be used for the inner ring 124a. When the NBR is used as described above, it is possible to provide an adhesion force between the inner circumferential surface of the outer ring 124b and the engaging groove 121g of the first piston 121 and to reduce the diameter of the outer ring 124b Will be compensated.

The outer ring 124b is formed in a circular cross-sectional shape that surrounds the inner ring 124a. A material having a small chemical resistance and a small wear factor may be used. For example, Teflon may be used. 124a so that the compartment spaces on both sides of the fork shaft 130 along the longitudinal direction of the fork shaft 130 are sealed with each other about the outer ring 124b.

As described above, the sealing assembly formed on the outer circumferential surface of each piston can be formed by the combination of the inner ring and the outer ring, and compared with the configuration in which the sealing ring is applied as a single sealing member, the inner ring 124a made of NBR Since the inner circumferential surface of the outer ring 124b made of Teflon is supported, durability is improved.

Although the sealing assembly 124 is formed on the outer circumferential surface of the first piston 121 in the present embodiment, the sealing assembly 124 is not limited to the second piston 122 and the third piston 123 It is needless to say that a sealing assembly having diameters different from each other may be applied according to the diameter of the piston.

The sealing assembly 124 as described above is also applied to the inner circumferential surface of the tight contact portion 103 so that the sealing performance between the tight contact portion 103 and the fork shaft 130 can be secured.

The dent portion 200 is configured to impart a sense of dutment according to the shift of the driver. The dent portion 200 includes a plurality of dentent grooves (not shown) formed on the outer circumferential surface of the fork shaft 130, A steel ball elastically supported in a radial direction may be provided. It is a well-known technology to give a sense of dutility in this configuration, so a detailed description is omitted.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

100: Intermediate transmission
102: Case
110: Fork shaft control unit
121: third piston
122: second piston
123: first piston
124: sealing assembly
124a: Inner ring
124b: outer ring
130; Fork shaft
131: Small neck

Claims (7)

At least one shift fork is provided so as to reciprocate along the axial direction of the fork shaft and the shift fork is connected to a sleeve for varying the gear ratio selectively between a plurality of gears coupled to the engine drive shaft, A shaft assembly comprising:
And a fork shaft control portion disposed on one end coaxial along the longitudinal direction of the fork shaft,
Wherein the fork shaft control unit includes:
case;
A first piston having a part of the fork shaft inserted into the case and reciprocating along an axial direction, the first piston being integrally coupled to the fork shaft and partitioning the inside of the case;
A second piston spaced a predetermined distance from the first piston along the axial direction of the fork shaft to surround the end of the fork shaft; And
And a third piston which is fixed to one end of the second piston and reciprocates along the axial direction of the fork shaft,
Wherein a coupling groove is formed radially inwardly on an outer circumferential surface of each of the first piston, the second piston, and the third piston, a sealing assembly is provided in each coupling groove,
A small diameter portion having a smaller diameter is formed at an end of the fork shaft, and the second piston is brought into tight contact with the small diameter portion so as to surround the fork shaft. The method according to claim 1,
The sealing assembly comprising: an inner ring; And
And an outer ring formed to surround the outer circumferential surface of the inner ring. 3. The method of claim 2,
Wherein the inner ring is made of NBR (nitrile-butadiene rubber), and the outer ring is made of Teflon. The method of claim 3,
Wherein the inner ring has a circular cross-sectional shape. delete The method according to claim 1,
Wherein the first piston is fixed to the second piston along an axial direction of the fork shaft so as to reciprocate integrally with the second piston. The method according to claim 6,
Wherein the second piston is slid in close contact with an inner circumferential surface of the third piston, a second piston protruding portion is formed radially outwardly on an outer circumferential surface of the end portion of the second piston so that the third piston, And is engaged and fixed by a jaw portion of the fork shaft assembly.

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