A limiting device for a manual transmission shift fork

Abstract

A limit device for a manual transmission shift fork comprises a housing, a fork shaft, and a fork. The fork shaft is supported by the housing, a connecting block is provided on the fork, a through hole is provided at the tail of the fork to form a sliding fit with the fork shaft, an axial strip-shaped limit groove is also provided at the tail of the fork, and the length of the strip-shaped limit groove is the shifting stroke distance. A limit pin is provided on the housing, and one end of the limit pin is inserted into the strip-shaped limit groove to form a sliding fit therewith, thereby limiting the movement of the shift fork. A limit boss is provided at the tail of the fork, and the strip-shaped limit groove is arranged on the limit boss. The limit pin is a stepped shaft, the small diameter section is a bare rod section inserted into the strip-shaped limit groove, the middle diameter section is a threaded section to fit with the threaded hole on the housing, and the large diameter section is a nut for fixing the limit pin. The limit pin is made of steel, and the fork is made of aluminum alloy. The present invention avoids cumulative tolerance, has a better shifting effect, and does not affect the NVH performance of the transmission.

Description

Technical Field

[0001] The invention relates to a manual transmission shift device, in particular to a limiting device for a manual transmission shift fork. Background Art

[0002] In the prior art, the transmission mostly uses the end face contact between the gear sleeve and the gear to form the axial limit of the shift stroke. This limit method involves many parts. Since the gear sleeve and gear are processed separately, it is inevitable that the allowable processing error will be generated during the processing. When these many parts are assembled together, the cumulative tolerance will increase, and it is easy to produce over-limit, thereby affecting the shifting effect, causing the vehicle to drive unsmoothly, and even causing traffic accidents. At the same time, the impact of the gear sleeve on the gear will also generate a large noise, affecting the NVH performance of the transmission. Summary of the invention

[0003] The purpose of the present invention is to provide a limit device for a manual transmission shift fork to improve the transmission shifting effect and prevent the noise generated during shifting from affecting the NVH performance of the transmission.

[0004] The technical solution of the present invention is: a limit device for a manual transmission shift fork, comprising a housing, a fork shaft, and a shift fork, wherein the shift fork shaft is supported by the housing, and the tail of the shift fork is slidably matched on the fork shaft through a through hole provided to form an axially movable structure, the shift fork is provided with a connecting block that is engaged with an external operating mechanism, and the tail of the shift fork is provided with a strip-shaped limit groove extending axially, the axial length of the strip-shaped limit groove is the shifting stroke distance, a limit pin is fixedly installed on the housing, and the extending end of the limit pin is inserted into the strip-shaped limit groove of the shift fork, the limit pin is slidably matched with the strip-shaped limit groove, and the moving stroke of the shift fork is limited by the limit pin.

[0005] The tail of the shift fork is integrally formed with a limiting boss, and the strip-shaped limiting groove is arranged on the limiting boss. The limiting boss is arranged on a side surface of the tail of the shift fork and extends transversely.

[0006] The limiting pin comprises a threaded section and a polished rod section, the threaded section is threadedly matched and fixed with a threaded hole arranged on the box body, and the polished rod section is inserted into the strip-shaped limiting groove of the shift fork.

[0007] The limit pin is a stepped shaft, the small diameter section of the stepped shaft is a polished rod section, the middle diameter section is a threaded section, and the large diameter section is a nut.

[0008] The limit pin is made of steel material, and the shift fork is made of aluminum alloy material.

[0009] The above technical solution is adopted: a strip-shaped limit groove is set on the shift fork, and a limit pin on the box is inserted into the limit groove to form a sliding fit, thereby limiting the movement stroke of the shift fork. The travel distance of this limiting method is determined by the strip-shaped limit groove on the shift fork. The sliding stroke of the strip-shaped limit groove is consistent with the movement stroke required for the shift limit. The limit pin is used to limit the shift fork, and the shift fork shift movement distance is accurate, thereby achieving a better shifting effect. It fundamentally eliminates the cumulative tolerance increase caused by the processing error of the assembly combination of multiple separately processed parts, resulting in the phenomenon of over-limitation, and can also prevent the tooth sleeve from colliding with the gear end face under the drive of the shift fork, reducing the impact noise.

[0010] The strip-shaped limiting groove is arranged on a limiting boss integrally formed at the tail of the shift fork. Since the limiting boss is integrally formed with the shift fork, a limiting groove is arranged on the limiting boss to ensure the limiting requirement without affecting the original thickness of the rest of the shift fork.

[0011] The threaded section on the limit pin is threadedly matched with the threaded hole set on the box body. When the limit pin is worn or broken and needs to be repaired, it is convenient for maintenance personnel to disassemble and install. The limit pin is set as a stepped shaft, and the shaft section with threads can ensure a sufficiently large diameter to ensure the connection strength. At the same time, the shaft end with a small diameter is matched with the strip-shaped limit groove to reduce the width of the strip-shaped limit groove, thereby preventing the size of the shift fork from increasing.

[0012] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the present invention;

[0014] Figure 2 It is a schematic diagram of the position limiting of the present invention;

[0015] Figure 3 It is a structural diagram of the shift fork of the present invention.

[0016] In the accompanying drawings, 1 is a shift fork, 1-1 is a strip-shaped limiting groove, 1-3 is a limiting boss, 1-4 is a fork foot of the shift fork, 2 is a shift fork shaft, 3 is a limiting pin, 3-1 is a threaded section of the limiting pin, 3-2 is a bare rod section of the limiting pin, 4 is a box body, 4-1 is a threaded hole on the box body, and 5 is a connecting block. DETAILED DESCRIPTION

[0017] See also Figures 1 to 3, an embodiment of a limit device for a manual transmission shift fork, comprising a housing 4, a fork shaft 2, and a fork 1, wherein the fork shaft 2 is supported by the housing 4, and the fork 1 is provided with a connecting block 5 that is engaged with an external operating mechanism, and the connecting block 5 is used to manipulate the movement of the fork 1, and the tail of the fork 1 is also provided with a through hole that forms a sliding fit with the fork shaft 2, so that when shifting, the connecting block 5 can manipulate the axial movement of the fork 1 on the fork shaft 2, and the fork feet 1-4 of the fork 1 are stuck in the annular groove of the gear sleeve, so as to drive the gear sleeve and the fork 1 to move in the same direction, thereby completing the shifting; in order not to affect the thickness of other parts of the fork, a limit boss 1-3 is integrally formed on the side surface of the tail of the fork 1, and a stopper is provided on the limit boss 1-3. An axially extending strip limit groove 1-1, the axial length of which is the shifting stroke distance; a limit pin 3 is fixedly installed on the housing 4, the limit pin 3 is a stepped shaft, the small diameter section of the limit pin 3 is a smooth rod section 3-2 inserted into the strip limit groove 1-1, the middle diameter section is a threaded section 3-1, which is threadedly matched with a threaded hole 4-1 provided on the housing 4, and the large diameter section is a nut that fixes the limit pin 3 on the housing 4; the limit pin 3 forms a sliding fit with the shift fork 1 through the smooth rod section 3-2 inserted into the strip limit groove 1-1, thereby realizing that the strip limit groove 1-1 limits the moving stroke of the shift fork 1, and the maximum moving distance of the shift fork 1 is limited to the axial length of the strip limit groove 1-1, that is, the maximum distance of the shifting stroke.

[0018] Combining the above structure Figure 2 It can be seen that when the transmission shifts gears, the external operating mechanism controls the shift fork 1 to move axially along the shift fork shaft 2 toward one end through the connection block, until one end of the strip-shaped limit groove 1-1 on the shift fork 1 is limited by the limit pin 3, and the shift fork 1 cannot move further, at this time the shift is in place; when the external operating mechanism controls the shift fork 1 to move axially along the shift fork shaft 2 toward the other end through the connection block, until the other end of the strip-shaped limit groove 1-1 on the shift fork 1 is limited by the limit pin 3, and the shift fork 1 cannot move further, at this time the shift is in place. Thus, the shifting limit of the shift fork 1 is realized by the cooperation between the strip-shaped limit groove 1-1 and the limit pin 3. The maximum distance that the shift fork 1 can move is the axial length of the strip-shaped limit groove 1-1, which is also the maximum distance of the shifting stroke.

[0019] In the present invention, only the strip limit groove 1-1 plays a decisive role in the shifting travel distance. Compared with the limiting method of the tooth sleeve and the gear, the cumulative tolerance is fundamentally eliminated, so that the sliding travel of the strip limit groove 1-1 is consistent with the moving distance required for the shifting limit. It can be seen that the cooperation between the strip limit groove 1-1 and the limit pin 3 is more precise, which avoids the occurrence of over-limiting and has a better shifting effect.

[0020] In order to avoid occupying too much space, in the present invention, the limit pin 3 is set as a stepped shaft, so that the light rod section 3-2 that cooperates with the strip limit groove 1-1 is a small diameter section, which can reduce the width of the strip limit groove 1-1, thereby making the limit boss 1-3 on the fork 1 relatively small, and reducing the space occupied by the fork 1; at the same time, the diameter of the threaded section 3-1 of the limit pin 3 is larger than the light rod section 3-2, thereby ensuring the connection strength of the limit pin 3.

[0021] In the present invention, the shift fork 1 is die-casted with aluminum alloy material. Since the aluminum alloy material has the characteristics of low density and high strength, the shift fork 1 contacts the limit pin 3 made of steel, and the impact sound is small, which will not affect the NVH performance of the transmission. Compared with the prior art in which the gear sleeve made of brass or steel cooperates with the gear to limit, the noise of the present invention is much smaller than the noise generated by the impact of the gear sleeve and the gear, and has a good noise reduction effect.

Claims

1. A limit device for a manual transmission shift fork, comprising a housing (4), a fork shaft (2), and a fork (1), wherein the fork shaft (2) is supported by the housing (4), and the tail of the fork (1) is slidably fitted on the fork shaft (2) through a through hole to form an axially movable structure, and the fork (1) is provided with a connecting block (5) for engaging with an external operating mechanism, characterized in that: The tail of the shift fork (1) is provided with a strip-shaped limiting groove (1-1) extending in the axial direction, the axial length of the strip-shaped limiting groove (1-1) is the shifting stroke distance, a limiting pin (3) is fixedly mounted on the housing (4), the extended end of the limiting pin (3) is inserted into the strip-shaped limiting groove (1-1) of the shift fork (1), the limiting pin (3) and the strip-shaped limiting groove (1-1) are slidably matched, and the moving stroke of the shift fork (1) is limited by the limiting pin (3); A limiting boss (1-3) is integrally formed at the tail of the shift fork (1), the strip-shaped limiting groove (1-1) is arranged on the limiting boss (1-3), and the limiting boss (1-3) is arranged on a side surface of the tail of the shift fork (1) and extends laterally; The limiting pin (3) comprises a threaded section (3-1) and a bare rod section (3-2); the threaded section (3-1) is threadedly matched and fixed with a threaded hole provided on the box body (4); and the bare rod section (3-2) is inserted into the strip-shaped limiting groove (1-1) of the shift fork (1).

2. The limiting device for a manual transmission shift fork according to claim 1, characterized in that: The limit pin (3) is a stepped shaft, the small diameter section of the stepped shaft is a polished rod section (3-2), the middle diameter section is a threaded section (3-1), and the large diameter section is a nut.

3. The limiting device for a manual transmission shift fork according to claim 1, characterized in that: The limit pin (3) is made of steel, and the shift fork (1) is made of aluminum alloy.

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