JP4905289B2 - transmission - Google Patents

Description

  The present invention relates to a transmission, and more particularly to a transmission in which an input shaft and an output shaft (counter shaft) are arranged on separate axes.

  Conventionally, in a transmission that is disposed on the side of an engine that is horizontally disposed, an input shaft and an output shaft (counter shaft) are juxtaposed on separate axes, and the input shaft and the output shaft (counter shaft) In many cases, a so-called horizontal type transmission in which a plurality of transmission gear sets are arranged is employed.

  As an example of such a horizontal transmission, a transmission as shown in Patent Document 1 below has been proposed.

  By the way, since a transmission meshes a plurality of gears to transmit driving torque, gear noise is generated when the vehicle travels. Thus, when gear noise occurs, the quietness of the vehicle deteriorates and passenger comfort is impaired.

  Therefore, various techniques for reducing this gear noise have been proposed. For example, the following Non-Patent Document 1 proposes a technique for reducing gear noise in an automatic transmission.

  In this gear noise reduction technology, it is suggested that “the mesh force is reduced by increasing the level of intersection of two gears' compliance (displacement per unit force)” as a “design policy for low gear noise design”. .

  Here, “mesh force” refers to a dynamic excitation force that strikes the tooth surface. As this mesh force increases, gear noise increases. Therefore, gear noise can be reduced by reducing this mesh force.

  In this document, as a specific measure of “increasing the level of intersection of compliance”, reducing the “weight (mass)” of the vibration mode and reducing the “spring constant (rigidity)” by thinning the gear. It is disclosed.

Japanese National Patent Publication No. 10-502160 Yasunori Kanda, 5 others, “ANALYTICAL APPROACH OF TRANSMISSION GEAR NOISE”, MPT2001-Fukuoka: The JSME International Conference on Motion and Power Transmissions, Japan Society of Mechanical Engineers, November 15, 2001, Vol. I, No.01-202, pp.126-131

  By the way, in a transmission in which a transmission gear and a drive shaft are integrated, such as a manual transmission, the vibration mode is mainly a bending mode of the drive shaft. It is conceivable to reduce gear noise by lowering the “spring constant”.

  Specifically, it is conceivable to reduce the “weight” and “spring constant” of the drive shaft by reducing the shaft diameter of the drive shaft. In particular, if a small diameter part is formed between the input point and output point of the drive torque, the bending stiffness of the drive shaft will be reduced, so the "spring constant" can be reduced and the level of intersection of compliance increased. be able to.

  However, since the drive shaft of the transmission needs to transmit the drive torque for driving the vehicle, if the portion where the high-load drive torque acts is reduced in diameter, the drive shaft cannot respond to the drive torque, and may be damaged. There is a problem of fear.

  Therefore, in the present invention, in a transmission that includes an input shaft and a counter shaft and a plurality of transmission gear sets are arranged between the shafts, the intersection level of compliance is increased while eliminating the risk of damage to the drive shaft. An object of the present invention is to provide a transmission capable of reducing gear noise.

  The transmission according to the present invention includes an input shaft for inputting driving force from the engine, a counter shaft disposed in parallel to the input shaft, and a differential shaft fixed to the counter shaft and driving a diff ring gear on the drive shaft. A transmission comprising: a drive gear; a plurality of speed change drive gears provided on the input shaft; and a plurality of speed change driven gears provided on the counter shaft in constant mesh with the speed change drive gear. A counter gear including a driven gear for the highest speed stage and a driven gear for the next high speed stage on the counter shaft, between the driven gear for the highest speed stage and the driven gear for the next high speed stage on the counter shaft; The counter shaft small-diameter portion that is smaller than the support portion diameter of the driven gear for the highest speed stage and the support portion diameter of the driven gear for the next high speed stage is formed in the portion that does not become the torque transmission path of .

According to the above configuration, the countershaft small-diameter portion is formed between the highest-speed driven gear on the countershaft and the driven gear for the next high-speed stage that does not serve as a torque transmission path for other speed stages. Will do. This makes it possible to reduce the diameter of the counter shaft by effectively using a portion that transmits only a relatively low load driving torque.
For this reason, it is possible to reduce the bending rigidity of the countershaft without reducing the diameter of the portion that transmits the high-load driving torque. In particular, by reducing the diameter of the portion between the driven gear for the highest speed stage and the driven gear for the next high speed stage, it is possible to increase the level of compliance at the time of running at the highest speed stage or at the next high speed stage. .
Here, “highest speed” and “next high speed” mean “6th speed” and “5th speed” in the case of a 6-speed transmission, and “5th speed” in the case of a 5-speed transmission. "4th gear" means the stage.
In addition, “a portion that does not become a torque transmission path for other gears” refers to a drive torque transmission path (an input part and an output part of a drive torque) when the vehicle travels at another speed (first speed, second speed, etc.). It means the part that is not between.

In one embodiment of the present invention, a first-speed drive gear and a second-speed drive gear are installed on the input shaft in order from the engine side, and the first-speed drive gear and the second-speed drive gear on the input shaft are installed. In between, the input shaft small-diameter portion that is smaller than the root diameter of the first-speed drive gear and the second-speed drive gear is formed.
According to the said structure, the bending rigidity of an input shaft can be reduced by forming on the input shaft the small diameter part of the input shaft smaller diameter than the gear root diameter. In particular, the 1st-speed drive gear is arranged on the engine side, and the input shaft small-diameter portion is formed between the first-speed drive gear and the 2nd-speed drive gear on the opposite side of the engine. It is possible to prevent the drive torque at the time of the first speed sudden start from acting on the small diameter portion of the input shaft.
For this reason, since the driving torque of the highest load is not transmitted to the small diameter portion of the input shaft while reducing the bending rigidity of the input shaft, the input shaft can be prevented from being damaged as much as possible.
Therefore, while preventing damage to the input shaft, it is possible to increase the intersection level of compliance and reduce gear noise.

In one embodiment of the present invention, the counter shaft includes a first counter shaft and a second counter shaft, and a plurality of low-speed stage driven gears are installed on the first counter shaft, A plurality of high-speed stage driven gears are installed on two countershafts, and the countershaft small diameter portion is formed only on the second countershaft.
According to the above configuration, by forming the countershaft small diameter portion on the second countershaft where the driven gears for the high speed stage are gathered and installed, only the bending rigidity of the second countershaft is reduced, and the low speed stage covered gear is thereby formed. The torsional rigidity of the first counter shaft in which the drive gears are collected and installed can be kept high.
Therefore, it is possible to prevent the possibility of breakage of the first counter shaft that transmits the high load driving torque, while effectively using the second counter shaft that transmits only the low load driving torque to increase the level of intersection of the compliance.

In one embodiment of the present invention, the countershaft in which the countershaft small-diameter portion is formed is configured by two-point support that is supported at both ends of the countershaft.
According to the above configuration, the support shaft of the counter shaft having a small diameter portion is supported by the two-point support having a lower support rigidity than the three-point support, so that the support rigidity of the counter shaft is lowered and the counter shaft is bent. This makes it easier to increase the compliance of the countershaft.
Therefore, the intersection level of compliance can be further increased, and gear noise can be further reduced.

In an embodiment of the present invention, an end portion of the counter shaft that is close to the counter shaft small diameter portion is supported by a ball bearing having lower support rigidity than the end portion on the opposite side of the end portion .
According to the above configuration, by supporting the end portion of the counter shaft in the vicinity of the counter shaft small diameter portion with the ball bearing having low support rigidity, the support stiffness in the vicinity of the counter shaft small diameter portion of the counter shaft is reduced, and the counter shaft Can bend more easily, and the compliance of the countershaft can be increased.
Therefore, the intersection level of compliance can be further increased, and gear noise can be further reduced.

In one embodiment of the present invention, the countershaft small diameter portion of the countershaft is, when viewed from the side, the support portion of the driven gear for the highest speed stage, the support portion and the minimum diameter portion of the driven gear for the next high speed stage. It is formed so as to be connected in a substantially arc shape.
According to the said structure, a countershaft small diameter part is formed as a substantially arc-shaped recessed part which is gentle on a countershaft.
For this reason, even if the countershaft small diameter portion is formed on the countershaft, the rigidity of the countershaft gradually changes. Therefore, even if a load is applied to the countershaft, stress concentration does not easily occur in the countershaft small diameter portion.
Therefore, it is possible to increase the compliance of the counter shaft while reducing the risk of breakage of the counter shaft.

In one embodiment of the present invention, a through hole extending in the axial direction is formed in the counter shaft small diameter portion of the counter shaft.
According to the said structure, the countershaft small diameter part is formed in a substantially cylindrical shape by forming the through-hole extended in an axial direction in the countershaft small diameter part.
For this reason, the countershaft small-diameter portion can be formed of a “tubular body” having a lower bending rigidity than a solid body having the same diameter.
Therefore, the bending rigidity of the counter shaft can be reduced without further reducing the shaft diameter, and the compliance of the counter shaft can be further increased.

According to the present invention, the bending rigidity of the counter shaft can be reduced without reducing the diameter of the portion that transmits the high-load driving torque. In particular, by reducing the diameter of the portion between the driven gear for the highest speed stage and the driven gear for the next high speed stage, it is possible to increase the level of compliance at the time of running at the highest speed stage or at the next high speed stage. .
Therefore, in a transmission that includes an input shaft and a counter shaft, and a plurality of transmission gear sets are arranged between the shafts, the level of compliance at high speeds can be increased while eliminating the risk of damage to the drive shaft. , Gear noise can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the gear train of the transmission of this embodiment will be described with reference to FIG. FIG. 1 is a skeleton diagram of a gear train of a transmission according to the present embodiment. In the following description, the engine side of the transmission is referred to as the transmission front side, and the non-engine side of the transmission is referred to as the transmission rear side.

  The transmission TM of the present embodiment is a so-called horizontal type manual transmission having a plurality of shafts, and is a manual transmission that achieves six forward speeds and one reverse speed.

  This transmission TM includes a laterally extending input shaft 1 that receives rotational driving force from the engine E, a first counter shaft 2 that is arranged in parallel to the input shaft 1, and an opposite side of the first counter shaft 2. Are provided with a second counter shaft 3 disposed in parallel with the input shaft 1 and a reverse shaft 4 disposed in parallel with the input shaft 1 on the first counter shaft 2 side. Further, the rotational drive force finally shifted is configured to be transmitted to the drive shaft 5 having drive wheels (not shown) at the left and right ends via the final ring gear 6.

  The input shaft 1 described above is rotatably supported by bearing members 11 and 12 at two locations, a front end on the front side of the transmission and a rear end on the rear side of the transmission, and a plurality of transmission gears and a synchronizer are provided therebetween. Provided.

  The transmission gears are arranged in order from the front side of the transmission: a 4-speed drive gear 13, a 1-speed drive gear 14, a 2-speed and 3-speed drive gear 15, a 6-speed drive gear 16, and a 5-speed drive gear 17. A total of five drive gears (13 to 17) are provided. Of these, the fourth speed drive gear 13, the first speed drive gear 14, the second speed and the third speed drive gear 15 are fixed to the input shaft 1, and the sixth speed drive gear 16 and the fifth speed drive gear 17 are provided. The input shaft 1 is supported idle. The 6-speed drive gear 16 and the 5-speed drive gear 17 are configured to be connected to the input shaft 1 during a shift shift by a 5-6 synchronizer 18 provided therebetween.

  The above-mentioned first counter shaft 2 is also rotatably supported by bearing members 21 and 22 at two locations, the front end and the rear end, and a plurality of transmission gears and a synchronizer are provided therebetween.

  The transmission gears are arranged in order from the transmission front side, the first output gear 23, the first-speed driven gear 24, and the second-speed driven gear 25. Among these, the first output gear 23 is fixed to the first counter shaft 2, and the first-speed driven gear 24 and the second-speed driven gear 25 are idle-supported on the first counter shaft 2. The first-speed driven gear 24 and the second-speed driven gear 25 are also configured to be connected to the first counter shaft 2 at the time of a shift shift by a 1-2 synchronizer 26 provided therebetween. Yes.

  The second countershaft 3 described above is also rotatably supported by bearing members 31 and 32 at two locations, the front end and the rear end, and a plurality of transmission gears and a synchronizer are provided therebetween.

  The transmission gear is arranged in order from the transmission front side with the second output gear 33, the fourth speed driven gear 34, the third speed driven gear 35, the sixth speed driven gear 36, and the fifth speed driven gear 37. ing. Among these, the second output gear 33, the 6th speed driven gear 36, and the 5th speed driven gear 37 are fixed to the second counter shaft 3, and the 4th speed driven gear 34 and the 3rd speed driven gear 37 are driven. 35 is supported on the second countershaft 3 for free rotation. The fourth-speed driven gear 34 and the third-speed driven gear 35 are also configured to be connected to the second countershaft 3 at the time of a shift shift by a 3-4 synchronizer 38 provided therebetween. Yes.

Of these, the third-speed driven gear 35 is configured to always mesh with the second-speed and third-speed drive gear 15 that is the same as the second-speed driven gear 25 on the first counter shaft 2.
For this reason, the drive gear for the second speed and the drive gear for the third speed are shared by the single drive gear (15), and the drive gear on the input shaft 1 can be reduced by one.

  The above-described reverse shaft 4 is rotatably supported by bearing members 41 and 42 at two locations, a front end and a rear end, and a plurality of transmission gears and a synchronizer are provided therebetween.

  The transmission gear is arranged as a third output gear 43 and a reverse gear 44 from the transmission front side, and among these, the third output gear 43 is fixed to the reverse shaft 4. The reverse gear 44 is supported by the reverse shaft 4 so as to be connected to the reverse shaft 4 at the time of reverse shift by an adjacent R synchronization device 45.

  The reverse gear 44 is always meshed with the first-speed driven gear 24 that is idle-supported on the first countershaft 2, and the reverse gear train is utilized by using the first-speed transmission gears (14, 24). Has achieved. For this reason, since it is not necessary to provide the drive gear for the reverse gear 44 in the input shaft 1, the drive gear on the input shaft 1 can further be reduced.

  A differential device 51 is provided at the center of the drive shaft 5, and the final ring gear 6 is fixed to the outer periphery of the differential device 51.

  Thus, the drive gears and the driven gears arranged on the respective shafts (1 to 4) are configured to always mesh with each corresponding gear position, and the respective synchronizers (18, 26, 38, 45). ), The rotational driving force of the engine E is output to the drive shaft 5 through the respective gear positions.

  Next, the torque flow of the transmission TM configured as described above will be described.

  First, at the neutral time, not all the synchronizers (18, 26, 38, 45) of the respective transmission gears are shifted (slidably moved in the axial direction). ~ 4) Rotate above. For this reason, even if the input shaft 1 rotates, the rotational driving force is not transmitted to the final ring gear 6 of the drive shaft 5, and the drive shaft 5 does not rotate.

  Next, at the first speed, the first-speed driven gear 24 is connected to the first counter shaft 2 by shifting the 1-2 synchronization device 26 to the first-speed driven gear 24 side. For this reason, when the input shaft 1 rotates, the rotational driving force is transmitted in the order of the first speed driving gear 14 → the first speed driven gear 24 → the first counter shaft 2 → the first output gear 23 → the final ring gear 6. Therefore, the rotation of the engine E is most decelerated to the drive shaft 5 and output.

  At the second speed, the 1-2 speed driven gear 25 is connected to the first counter shaft 2 by shifting the 1-2 synchronizing device 26 to the second speed driven gear 25 side. For this reason, when the input shaft 1 rotates, the rotational driving force follows the flow of the second and third speed driving gear 15 → the second speed driven gear 25 → the first counter shaft 2 → the first output gear 23 → the final ring gear 6. Is transmitted, and the rotation of the engine E is decelerated to the drive shaft 5 and output.

  At the third speed, the third-speed driven gear 35 is connected to the second counter shaft 3 by shifting the 3-4 synchronizer 38 to the third-speed driven gear side 35. For this reason, when the input shaft 1 rotates, the rotational driving force follows the flow of the second and third speed drive gear 15 → the third speed driven gear 35 → the second counter shaft 3 → the second output gear 33 → the final ring gear 6. Is transmitted, and the rotation of the engine E is increased and output to the drive shaft 5 with respect to the second speed.

  Further, at the time of the fourth speed, the 4th-speed driven gear 34 is connected to the second countershaft 3 by shifting the 3-4 synchronizer 38 to the fourth speed driven gear 34 side. For this reason, when the input shaft 1 rotates, the rotational driving force is transmitted in the flow of the fourth speed drive gear 13 → the fourth speed driven gear 34 → the second counter shaft 3 → the second output gear 33 → the final ring gear 6. Therefore, the rotation of the engine E is increased and output to the drive shaft 5 with respect to the third speed.

  Further, at the time of the fifth speed, the fifth-speed driving gear 17 is connected to the input shaft 1 by shifting the 5-6 synchronizer 18 to the fifth-speed driving gear 17 side. For this reason, when the input shaft 1 rotates, the rotational driving force is transmitted in the flow of the fifth speed driving gear 17 → the fifth speed driven gear 37 → the second counter shaft 3 → the second output gear 33 → the final ring gear 6. Therefore, the rotation of the engine E is increased and output to the drive shaft 5 with respect to the fourth speed.

  Finally, at the sixth speed, the 6-6 speed drive gear 16 is connected to the input shaft 1 by shifting the 5-6 synchronizer 18 to the 6th speed drive gear side 16. For this reason, when the input shaft 1 rotates, the rotational driving force is transmitted in the flow of 6-speed driving gear 16 → 6-speed driven gear 36 → second counter shaft 3 → second output gear 33 → final ring gear 6. As a result, the rotation of the engine E is accelerated to the drive shaft 5 and output.

  On the other hand, at the time of reverse, the reverse gear 44 is connected to the reverse shaft 4 by shifting the R synchronization device 45 to the reverse gear 44 side. Therefore, when the input shaft 1 rotates, the rotational driving force is generated by the flow of the first speed driving gear 14 → the first speed driven gear 24 → the reverse gear 44 → the reverse shaft 4 → the third output gear 43 → the final ring gear 6. The rotation of the engine E is reversed to the drive shaft 5 and output.

  Through the series of torque flows described above, the transmission TM according to the present embodiment achieves the sixth forward speed and the first reverse speed.

  Next, the detailed structure of the transmission of this embodiment will be described with reference to FIG. FIG. 2 is a developed sectional view of the transmission. Descriptions of main components are omitted by using the same reference numerals as those in FIG.

  The transmission TM includes a transmission case 7 that supports three axes of the first counter shaft 2, the second counter shaft 3, and the reverse shaft 4 that are arranged in parallel with the input shaft 1 described above. The transmission case 7 includes a clutch housing 8 set on the front side of the transmission and a transmission casing 9 set on the rear side of the transmission.

  The clutch housing 8 has a clutch housing recess 81 for housing the clutch device C, a differential housing recess 82 for housing the differential device 51, and a through hole 83 through which the input shaft 1 is inserted in the axial direction. Front end support portions 84a, 84b, 84c that support the front end portions of the three axes (2, 3, 4) other than the input shaft 1 are formed on the side surfaces.

  On the other hand, the transmission case 9 is constituted by a bottomed cylindrical case body, houses each transmission gear in the interior 91, and supports the rear end portion of each shaft (1, 2, 3, 4). 92a, 92b, 92c, and 92d are formed on the inner side surface.

  The clutch housing 8 and the transmission casing 9 thus configured are combined at the peripheral mating surfaces, and are fastened and fixed by a plurality of fastening bolts 10 (only one is disclosed in FIG. 2), thereby constituting the transmission case 7. is doing.

  A clutch plate 20 of the clutch device C is fixed to a spline portion 19 formed at the front end of the input shaft 1 so that the clutch plate 20 receives the rotational driving force of the engine E from the flywheel F of the engine E. It is composed.

  A four-speed drive gear 13 is fitted and fixed to the input shaft 1 adjacent to the front bearing member 11 and firmly fixed, while the first-speed drive gear 14 and the second-speed and third-speed drive gear 15 are fixed. Is formed integrally with the input shaft 1. A needle bearing n is interposed between the 6-speed drive gear 16 and the 5th-speed drive gear 17 that are supported to idle and the input shaft 1.

As described above, the first-speed drive gear 14 and the second-speed and third-speed drive gear 15 are integrally formed with the input shaft 1, so that a low-speed drive gear (14, 15) on which a large drive torque acts. And the coupling strength between the input shaft 1 can be increased.
In particular, the first-speed drive gear 14 and the second-speed and third-speed drive gear 15 function as drive gears for two shift speeds (first speed, reverse speed, second speed, and third speed). However, since the frequency at which the driving torque acts increases and the coupling strength needs to be increased, the input shaft is formed integrally with the input shaft 1 in the present embodiment, so that the input shaft can be used without using an extra reinforcing structure. The bonding strength with 1 can be increased.

  The 5-6 synchronizer 18 includes a clutch hub 18a, a sleeve 18b, and a synchronizer unit 18c, as in the known synchronizer, and includes the 6-speed drive gear 16 or the 5-speed drive gear 17 and the input shaft 1. It is configured to be linked in synchronization.

  The 6-speed drive gear 16 and the 5-speed drive gear 17 have a large-diameter 6-speed drive gear 16 disposed on the front side of the transmission and a small-diameter 5-speed drive gear 17 disposed on the rear side of the transmission. Yes. For this reason, the external dimension of the transmission rear-end part of the input shaft 1 can be made as small as possible.

  Further, the front and rear end bearing members 11 and 12 have a front end constituted by a roller bearing 11 and a rear end constituted by a ball bearing 12. By using the roller bearing 11 that supports the front end by line contact, the input shaft 1 can be reliably supported even when a large impact is applied from the clutch device C at the front end of the input shaft 1.

  The first countershaft 2 is integrally formed with a first output gear 23 adjacent to the front bearing member 21. A needle bearing n is interposed between the first-speed driven gear 24 and the second-speed driven gear 25 that are supported to idle.

  The 1-2 synchronizer 26 is also provided with a clutch hub, a sleeve, and a synchronizer unit (not provided with a symbol), similarly to the known synchronizer, and the first-speed driven gear 24 or the second-speed driven gear 25 is provided. The first counter shaft 2 is configured to be connected in synchronization.

  The first-speed driven gear 24 and the second-speed driven gear 25 are arranged with a large-diameter first-speed driven gear 24 on the front side of the transmission and a small-diameter two-speed driven gear on the rear side of the transmission. 25 is arranged. For this reason, the external dimension of the transmission rear-end part of the 1st countershaft 2 can also be made as small as possible.

  As described above, since the gear arrangement of the first counter shaft 2 and the gear arrangement of the input shaft 1 are set, in the transmission TM of the present embodiment, the rear end portion of the transmission can be configured compactly. Can increase the sex.

  That is, as shown in the perspective view of the transmission in the in-vehicle state as viewed from the front side of the vehicle in FIG. 3, the front of the transmission TM extends in the front-rear direction of the vehicle body above the rear side (upward side in the vehicle width direction). The side frame SF is disposed, and the transmission TM needs to be disposed so as not to interfere with the front side frame SF.

  Therefore, in the present embodiment, a 5-speed drive gear 17 having a smaller diameter than the 6-speed drive gear 16 is disposed at the transmission rear end portion of the input shaft 1, and at the transmission rear end portion of the first counter shaft 2. By arranging the second-speed drive gear 25 having a smaller diameter than the first-speed driven gear 24, the rear end portion 7a of the transmission case 7 is configured to be compact, and interference with the front side frame SF is prevented. It is out.

  Further, as shown in FIG. 2, the front and rear end bearing members 21 and 22 have a front end constituted by a taper bearing 21 facing the rear side of the transmission and a rear end constituted by a taper bearing 22 facing the front side of the transmission. Yes. Since the taper bearing has a relatively large load capacity even with a small bearing size, the first counter shaft 2 on which a large driving torque acts by providing the first-speed driven gear 24 and the second-speed driven gear 26 is provided. Even so, it can be supported in a compact space.

  As shown in FIG. 2, the second counter shaft 3 is integrally formed with a second output gear 33 adjacent to the front bearing member 31. Further, a needle bearing n is interposed between the fourth-speed driven gear 34 and the third-speed driven gear 35 that are supported for free rotation. At the rear, the 6th speed driven gear 36 and the 5th speed driven gear 37 are fixed by fitting.

  The 3-4 synchronizer 38 is also provided with a clutch hub, a sleeve, and a synchronizer unit (not provided with a reference numeral), like the other synchronizers, and the 4-speed driven gear 34 or the 3-speed driven gear 35; The second counter shaft 3 is configured to be connected in synchronization.

  Further, the front and rear end bearing members 31 and 32 have a rear end constituted by a roller bearing 31 and a rear end constituted by a ball bearing 32. By configuring the front end with the roller bearing 31, the meshing reaction force with the final ring gear 6 from the second output gear 33 can be appropriately supported.

On the other hand, by constituting the bearing member at the rear end with a ball bearing 32, as will be described later, the support rigidity is lowered to support the second counter shaft 3 in order to reduce gear noise.

  The reverse shaft 4 also integrally forms a third output gear 43 adjacent to the front bearing member 41. Further, a needle bearing n is interposed between the reverse gear 44 and the idle supported.

  The R synchronization device 45 also includes a clutch hub, a sleeve, and a synchronizer unit (not provided with a reference numeral), and is configured to connect the reverse gear 44 and the reverse shaft 4 in synchronization.

  Also, the front and rear end bearing members 41 and 42 are configured with a tapered bearing 41 facing the rear side of the transmission at the front end and a tapered bearing 42 facing the front side of the transmission, like the first counter shaft 2. is doing. For this reason, even if it is the reverse shaft 4 which is provided with the reverse gear 44 and a big drive torque acts, it can be supported in a compact space.

  The final ring gear 6 is fastened and fixed to the outer periphery of the differential casing 52 of the differential device 51 disposed on the drive shaft 5 by fastening bolts 53. The final ring gear 6 uses the first output gear 23, the second output gear 23, and the like. All the rotational driving forces from the second output gear 33 and the third output gear 43 are received.

  The differential casing 52 of the differential device 51 is supported by the clutch housing 8 and the transmission casing 9 via bearing members 54 and 55. These bearing members 54 and 55 are also constituted by tapered bearings in order to support a large load in a compact space.

  As can be seen from FIG. 2, the lengths of the input shaft 1, the first counter shaft 2, the second counter shaft 3, and the reverse shaft 4 are changed depending on the number of transmission gears arranged.

  In particular, since the first counter shaft 2 is provided with only two gears, a first speed driven gear 24 and a second speed driven gear 25, the first counter shaft 2 is configured to be shorter than the second counter shaft 3. Also, the reverse shaft 4 is configured to be shorter because only the reverse gear 44 is provided.

  As described above, by configuring the first counter shaft 2 and the reverse shaft 4 to be short, the transmission TM of the present embodiment improves the mountability to the vehicle.

  Next, the shaft diameter and the like of each drive shaft will be described with reference to FIG. FIG. 4 is a detailed cross-sectional view of main parts of the input shaft, the first counter shaft, and the second counter shaft.

  As shown in FIG. 4, a counter shaft small diameter portion 61 having a smaller diameter than other portions is formed between the 6th speed driven gear 36 and the 5th speed driven gear 37 of the second countershaft 3. Yes.

  The countershaft small-diameter portion 61 has a minimum diameter d3 smaller than the diameter d1 of the support portion 62 that supports the sixth-speed driven gear 36 and the diameter d2 of the support portion 63 that supports the fifth-speed driven gear 37. Centering on the part 61a, it is constituted by recessing the same length as the 5-6 synchronizer 18 in the axial direction in a side view.

  Thus, by forming the countershaft small diameter portion 61, the bending rigidity and weight of the second countershaft 3 can be reduced, and the compliance of the second countershaft 3 can be increased as will be described later.

Since the countershaft small diameter portion 61 is provided between the 6th speed driven gear 36 and the 5th speed driven gear 37 on the rear side of the second countershaft 3, the vehicle travels at other low speed stages. Sometimes, it is not a drive torque transmission path, and a high load drive torque does not act.
That is, the second output gear 33 that is the output point of the second countershaft 3 is installed on the front side of the second countershaft 3, and the 3-4 synchronizer 38 that is the input point of the third and fourth speed drive torque. Is installed at the center of the second countershaft 3, the driving torque is not transmitted to the countershaft small diameter portion 61 during the third speed traveling and the fourth speed traveling, and the first speed driven gear 24 and the second speed are also transmitted. Since the driven gear 25 is provided on the first counter shaft 2, the driving torque is not transmitted to the second counter shaft 3 in the first speed traveling and the second speed traveling. For this reason, the drive torque does not act on the countershaft small diameter portion 61 when the vehicle travels at a low speed other than the fifth and sixth speeds.

  For this reason, the countershaft small-diameter portion 61 can be made as small as possible only by determining the shaft diameter dimension in consideration of only the driving torque at the time of 5th speed traveling and 6th speed traveling at a relatively low load.

  Further, an outer shape line 61L in a side view of the countershaft small diameter portion 61 is formed so as to be recessed in a smooth substantially circular arc shape, and this outer shape line 61L is formed by the support portion 62 of the 6-speed driven gear 36, It is formed so as to connect the minimum diameter portion 61a and the support portion 63 of the fifth speed driven gear 37.

  For this reason, since the cross-sectional shape of the second countershaft 3 does not change abruptly at the countershaft small diameter portion 61, even when a torsional load is applied to the second countershaft 3, stress is applied to the countershaft small diameter portion 61. Concentration can be prevented from occurring.

Further, the support portion 63 of the fifth-speed driven gear 37 located on the rear side of the transmission of the countershaft small diameter portion 61 has a diameter d2 larger than the diameter d3 of the minimum diameter portion 61a of the countershaft small diameter portion. .
This is because a large number of spline teeth (not shown) for fitting and fixing the fifth-speed driven gear 37 are formed on the outer peripheral surface of the support portion 63 of the fifth-speed driven gear 37 as much as possible. It is the diameter. By doing so, the coupling strength between the fifth-speed driven gear 37 and the second countershaft 3 is increased.

  Further, the counter shaft small diameter portion 61 is formed with a through hole portion 64 extending in the axial direction. By providing the through-hole portion 64, the countershaft small diameter portion 61 can be configured as a so-called “tubular body”, and the torsional rigidity can be further reduced.

  The second countershaft 3 provided with the countershaft small-diameter portion 61 is not limited to the fifth-speed driven gear 37 and the sixth-speed driven gear 36. Only the driven gear 34 is set, and only a relatively low driving torque is applied to the first counter shaft 2 provided with the first-speed driven gear 24 and the second-speed driven gear 25. For this reason, even if the weak part called the countershaft small diameter part 61 is provided, the possibility of damage can be reduced.

  Further, the second counter shaft 3 is constituted by two-point support in which the two ends at both ends thereof are supported by the bearing members 31 and 32 as described above. For this reason, the support rigidity of the second countershaft 3 is lower than the three-point support that is generally used in a horizontal transmission, and the second countershaft 3 is relatively easily bent.

An input shaft small-diameter portion 71 is provided between the first-speed drive gear 14 and the second-speed drive gear 15 on the input shaft 1.
The input shaft small diameter portion 71 is formed to have a diameter d6 smaller than the tooth bottom diameter (tooth diameter) d4 of the first speed drive gear 14 and the tooth bottom diameter d5 of the second speed drive gear 15. The input shaft 1 is configured to be recessed in a side view in substantially the same length as the 1-2 synchronizer 26 in the axial direction.

  Thus, by providing the input shaft 1 with the small diameter portion 71 on the input shaft 1, the bending rigidity and weight of the input shaft 1 can be reduced, and the compliance of the input shaft 1 can be increased as will be described later.

Further, since the input shaft small diameter portion 71 is provided on the rear side of the transmission of the first speed drive gear 14, the driving torque at the first speed, which is the highest load drive torque, is applied to the input shaft small diameter portion 71. Does not work.
That is, the drive torque input from the clutch device C (see FIG. 2) at the transmission front end of the input shaft 1 is transmitted to the first counter shaft 2 via the first-speed drive gear 14 when traveling at the first speed. Therefore, the drive torque is not transmitted to the input shaft small diameter portion 71 on the rear side of the transmission of the first-speed drive gear 14.

  In addition, since the input shaft small diameter portion 71 is provided at this position, the driving torque is transmitted by the 5-speed driving gear 17 and the 6-speed driving gear 16 installed on the rear side of the transmission, during the 5th and 6th speed traveling. Since the input shaft small diameter portion 71 serves as a torque transmission path, as will be described later, the compliance of the input shaft 1 can be increased, and the value of the intersection of the compliance can be reliably increased.

  Next, the relationship between the mesh force of the gear and the compliance of the input shaft and the second counter shaft will be described with reference to FIGS. FIG. 5 shows a graph of FEM (Finite Element Method) analysis showing the relationship between the mesh force and the compliance of each axis in the conventional structure, and FIG. 6 shows the mesh force and the compliance of each axis in the proposed structure. It is the figure which showed the graph of the FEM analysis which showed this relationship.

First, as shown in the lower diagram of FIG. 5, the compliance of the input shaft and the compliance of the second counter shaft of the conventional structure have characteristics as indicated by a one-dot chain line and a broken line in each frequency band.
Here, compliance is the “displacement amount per unit force”. Therefore, in the frequency band where the compliance value is high, each axis is greatly displaced (vibrated). In the frequency band where the value is low, each axis is hardly displaced (not shaken).

The relationship between mesh force and compliance is expressed by the following equation.
Mesh force = 1 / (input shaft compliance + second counter shaft compliance + 2 / (tooth rigidity))
This indicates that the mesh force decreases when the sum of the compliance of the input shaft 1 and the compliance of the second counter shaft 3 is high.
That is, when the input shaft 1 and the second counter shaft 3 are largely displaced, the tooth contact of the gear is changed, and the dynamic excitation force generated on the tooth surface is dispersed, thereby reducing the mesh force. .

  Therefore, as for the relationship between mesh force and compliance, if the value of the intersection of the input axis compliance and the second counter axis compliance is high, the mesh force peak value decreases, while the input axis compliance and the second counter axis compliance If the value of the intersection point is low, the mesh force peak value increases.

  Therefore, as shown in the figure, in the normal range of 500-2000 Hz when traveling at the 6th speed, there is an intersection CP1 having the lowest compliance between the input shaft and the second counter shaft in the vicinity of 1050 Hz. As shown in the upper diagram, it can be seen that the mesh force (MP1) near 1050 Hz is the highest, and the gear noise of the transmission TM increases at the peak value MP1.

On the other hand, the compliance of the input shaft 1 and the compliance of the second counter shaft 3 of the proposed structure have characteristics as indicated by a one-dot chain line and a broken line in each frequency band, as shown in the lower diagram of FIG.
That is, the compliance of the input shaft 1 and the compliance of the second countershaft 3 of the present plan are reduced in bending rigidity and weight due to the provision of the input shaft small diameter portion 71 and the counter shaft small diameter portion 61. As a result, it generally increases.

  For this reason, as shown in the figure, in the normal range of 500-2000 Hz when driving at the sixth speed, the intersection CP2 of the compliance of the input shaft 1 and the compliance of the second counter shaft 3 is at a relatively high position around 700 Hz. As shown in the upper diagram of FIG. 6, the mesh force has a peak value MP2 near 700 Hz, but is lower than the conventional peak value MP1, so the gear noise of the corresponding transmission TM is also low. It can be kept low.

  From the above, by providing the counter shaft small diameter portion 61 on the second counter shaft 3 and providing the input shaft small diameter portion 71 on the input shaft 1 as in this embodiment, the compliance of the shafts 3 and 1 can be improved. Since it can be increased, the intersection of compliance can be relatively increased, the mesh force peak value can be lowered, and gear noise can be reduced.

Next, the effect of this embodiment comprised in this way is demonstrated.
The transmission TM of this embodiment includes a 6-speed driven gear 36 and a 5-speed driven gear 37 on the second counter shaft 3, and the 6-speed driven gear 36 and the 5-speed driven gear 37. A countershaft small diameter portion 61 is formed on the second countershaft 3 in between.

Thereby, the diameter of the second countershaft 3 can be reduced by effectively using the portion of the second countershaft 3 that transmits only the relatively low-load fifth-speed driving torque.
For this reason, it is possible to reduce the bending rigidity of the second countershaft 3 without reducing the diameter of the portion where the high-load driving torque acts. Particularly, by reducing the diameter of the portion between the 6th speed driven gear 36 and the 5th speed driven gear 37, it is possible to increase the level of intersection of compliance during 6th speed traveling and 5th speed traveling.
Therefore, in the transmission TM including the input shaft 1 and the second counter shaft 3 and arranging a plurality of transmission gear sets between the shafts 1 and 3, while eliminating the risk of damage to the second counter shaft 3, Gear noise can be reduced by increasing the intersection level of compliance during high-speed driving.

In this embodiment, the first-speed drive gear 14 and the second-speed drive gear 15 are installed on the input shaft 1 in order from the transmission front side, and the first-speed drive gear 14 and the second-speed drive gear of the input shaft 1 are installed. An input shaft small diameter portion 71 is formed between the drive gears 15.
Thereby, the bending rigidity of the input shaft 1 can be reduced. In particular, the first-speed drive gear 14 is disposed on the front side of the transmission, and the input shaft small-diameter portion 71 is formed between the first-speed drive gear 14 and the second-speed drive gear 15 on the rear side of the transmission. As a result, the driving torque at the time of the first-speed sudden start of the highest load can be prevented from acting on the input shaft small diameter portion 71.
For this reason, since a large driving torque does not act on the input shaft small diameter portion 71 while reducing the bending rigidity of the input shaft 1, damage to the input shaft 1 can be prevented as much as possible.
Therefore, while preventing damage to the input shaft 1, it is possible to increase the compliance intersection level and reduce gear noise.

In this embodiment, a plurality of low-speed stage driven gears (24, 25) are installed on the first countershaft 2, while a plurality of high-speed stage driven gears (34, 35, 36, 37) are installed, and only the second countershaft 3 is formed with the countershaft small diameter portion 61.
As a result, only the bending rigidity of the second countershaft 3 is reduced, and the torsional rigidity of the first countershaft 2 in which the low-speed driven gears (24, 25) are collected and installed can be maintained high.
Therefore, while using the second countershaft 3 that acts only on the low-load driving torque to increase the level of intersection of compliance, the first countershaft 2 on which the high-load driving torque acts is prevented from being damaged. be able to.

In this embodiment, the second countershaft 3 on which the countershaft small diameter portion 61 is formed is supported by two-point support.
Thereby, the support rigidity of the second countershaft 3 is reduced by supporting the second countershaft 3 formed with the countershaft small diameter portion 61 by the two-point support having a lower support rigidity than the three-point support, By making the second countershaft 3 easy to bend, the compliance of the second countershaft 3 can be further increased.
Therefore, the intersection level of compliance can be further increased, and gear noise can be further reduced.

In this embodiment, the rear end portion of the second counter shaft 3 that is close to the counter shaft small diameter portion 61 is supported by the small diameter ball bearing 32.
Thereby, the compliance of the second countershaft 3 can be further increased by reducing the support rigidity of the second countershaft 3 in the vicinity of the countershaft small diameter portion 61 and making the second countershaft 3 more flexible.
Therefore, the intersection level of compliance can be further increased, and gear noise can be further reduced.

Further, in this embodiment, the counter shaft small diameter portion 61 is disposed between the support portion 62 of the 6th speed driven gear 36 and the support portion 63 and the minimum diameter portion 61a of the 5th speed driven gear 37 in a side view. It is formed so as to be tied in a substantially arc shape (61L).
As a result, the countershaft small diameter portion 61 is formed as a gentle arc-shaped recess on the second countershaft 3.
For this reason, even if the countershaft small diameter portion 61 is formed on the second countershaft 3, the rigidity of the second countershaft 3 gradually changes. Therefore, even if a load is applied, stress is concentrated on the countershaft small diameter portion 61. Is less likely to occur.
Therefore, the risk of the second countershaft 3 being damaged can be reduced, and the compliance of the second countershaft 3 can be increased.

In this embodiment, a through-hole portion 64 extending in the axial direction is formed in the counter shaft small diameter portion 61 of the second counter shaft 3.
Thereby, the countershaft small diameter part 61 is formed in a substantially cylindrical shape.
For this reason, the countershaft small-diameter portion 61 can be formed of a “tubular body” having a lower bending rigidity than a solid body having the same diameter.
Therefore, the bending rigidity of the second countershaft 3 can be reduced without further reducing the diameter of the countershaft small diameter portion 61, and the compliance of the second countershaft 3 can be further increased.

  In this embodiment, the input shaft 1 is provided with the input shaft small diameter portion 71 and the second counter shaft 3 is provided with the counter shaft small diameter portion 61. However, the counter shaft small diameter portion is provided only on the second counter shaft 3. 61 may be provided to increase the level of intersection of compliance. This is because even in the case of such a configuration, at least gear noise at the time of traveling at the fifth speed and the sixth speed can be reduced.

  Also, the installation position of the 6th speed driven gear 36 and the installation position of the 5th speed driven gear 37 are opposite to this embodiment, and the 5th speed driven gear 37 is installed on the front side of the transmission. The sixth speed driven gear 36 may be installed on the rear side of the transmission.

  Furthermore, in this embodiment, the description has been made on the assumption that the transmission has two countershafts 2 and 3. However, the present invention may be implemented by a general transmission having one countershaft.

As described above, in the correspondence between the configuration of the present invention and the above-described embodiment,
The diff ring gear of the present invention corresponds to the final ring gear 6 of the embodiment,
Similarly,
The differential drive gear corresponds to the second output gear 33,
The highest speed driven gear corresponds to the 6th speed driven gear 36,
The next high-speed driven gear corresponds to the fifth-speed driven gear 37,
The present invention is not limited to the above-described embodiments, but includes embodiments applied to all transmissions.
The transmission of the present invention is not limited to a manual transmission. For example, the control rod for operating the synchronization device is applied to a transmission having an automatic transmission function that is operated by an electric motor, a hydraulic actuator, or the like. Also good.

The skeleton figure of the gear train of the transmission of this embodiment. The expanded sectional view of a transmission. The perspective view of the transmission in the vehicle-mounted state seen from the vehicle front side. The principal part sectional drawing of an input shaft, a 1st countershaft, and a 2nd countershaft. The graph of the FEM analysis which showed the relationship between the mesh force in a conventional structure, and the compliance of each axis. The graph of the FEM analysis which showed the relationship of the mesh force in this proposal structure, and the compliance of each axis | shaft.

E ... Engine TM ... Transmission 1 ... Input shaft 2 ... First counter shaft 3 ... Second counter shaft 4 ... Reverse shaft 5 ... Drive shaft 6 ... Final ring gear 14 ... First speed drive gear 15 ... Second speed drive gear
32 ... Ball bearing 36 ... 6-speed driven gear 37 ... 5th-speed driven gear 61 ... Counter shaft small diameter part 64 ... Through hole 71 ... Input shaft small diameter part

Claims (7)

An input shaft for inputting a driving force from the engine, a counter shaft arranged in parallel to the input shaft, a differential driving gear fixed to the counter shaft and driving a diff ring gear on the drive shaft, and the input shaft A transmission comprising a plurality of shift drive gears provided on the top and a plurality of shift driven gears provided on the countershaft that are always meshed with the shift drive gears,
The counter shaft is provided with a driven gear for the highest speed stage and a driven gear for the next high speed stage,
The portion of the counter shaft between the driven gear for the highest speed stage and the driven gear for the next highest speed stage that does not serve as a torque transmission path for the other speed stages, A transmission having a countershaft small diameter portion that is smaller than the support portion diameter of the driven gear for the next high speed stage. On the input shaft, the first-speed drive gear and the second-speed drive gear are installed in order from the engine side,
Between the first-speed drive gear and the second-speed drive gear on the input shaft, an input shaft small-diameter portion that is smaller than the root diameter of the first-speed drive gear and the second-speed drive gear is formed. The transmission according to claim 1. The counter shaft is composed of a first counter shaft and a second counter shaft,
While installing a plurality of low-speed driven gears on the first counter shaft,
A plurality of high-speed stage driven gears are installed on the second counter shaft,
Only said second counter shaft, transmission of claim 1 or 2 wherein the formation of the counter shaft small diameter portion. The counter shaft forming the counter shaft small diameter portion, transmission according to what Re of claims 1-3 which is composed of two-point support for performing supported at both ends of the counter shaft. The transmission according to claim 4, wherein an end portion of the counter shaft that is close to the small-diameter portion of the counter shaft is supported by a ball bearing having lower support rigidity than an end portion on the opposite side of the end portion . The counter shaft small diameter portion of the counter shaft is connected in a substantially circular arc shape between the support portion of the driven gear for the highest speed stage, the support portion of the driven gear for the next high speed stage, and the minimum diameter portion in a side view. transmission according to what Re one of claims 1 to 5 which is formed in the. The counter shaft small diameter portion of the counter shaft, the transmission according to what Re of claims 1 to 6, to form a through hole extending in the axial direction.

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