JP6066273B2 - Transmission gear structure - Google Patents

Description

  The present invention relates to a gear structure of a transmission mounted on a vehicle.

  A plurality of forward gears and a reverse gear (reverse gear) are provided, and an always-meshing automobile transmission (transmission) in which gears corresponding to each other are always meshed at any gear position (shift position). It has been known. In the case of the forward gear, the gear supported by the input shaft and the gear supported by the counter shaft are directly meshed with each other. On the other hand, in the case of the reverse gear, the gear supported by the input shaft and the idler gear mesh with each other, and the idler gear and the reverse gear supported by the counter shaft mesh with each other. That is, the reverse gears do not mesh directly but mesh with each other via the idler gear.

JP 2004-197772 A

  In the above transmission, a gap (backlash) is set between the gears meshing with each other, and therefore, collision (tooth beat) between tooth surfaces occurs due to a fluctuation component included in the engine output. Such gear rattling excitation force is determined by the relative collision speed of the gear and the moment of inertia of the gear, which are determined by the rotational fluctuation of the engine and the magnitude of the backlash of the gear. As the value increases, the excitation force increases, and as a result, the rattling noise increases. Therefore, during idle operation where the gear position is neutral and the engine is idling, the rotational fluctuation component that is input to the transmission increases, which may cause excessive noise due to gear rattling (tooth rattling noise). is there. For this reason, for example, there is a gear that meshes with each other and rotates during idle operation, such as a structure in which a gear fixedly supported by an input shaft and a gear supported by a countershaft via a synchromesh mechanism are always meshed. When doing so, it is preferable to suppress the occurrence of rattling.

  As a method for suppressing the occurrence of rattling, it is effective to apply a rotational resistance to at least one of the gears that rotate while meshing with each other, and press the tooth surfaces by the rotational resistance.

  Here, in a structure in which a plurality of gears are supported on the countershaft via a synchromesh mechanism, rotational resistance is added to each gear by providing each synchromesh of the plurality of synchromesh mechanisms in the axial direction. It is possible to suppress gear rattling.

  However, in the case of the reverse gear, the idler gear that meshes with the reverse gear is a mere idle gear that is not provided with a synchro cone, and is rotatably supported by a support shaft fixed to the casing. For this reason, rattling is likely to occur between the idler gear and the reverse gear, and rattling noise is likely to increase.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce gear rattling noise during idle operation.

  In order to achieve the above object, the transmission gear structure of the present invention includes an input shaft, a first gear, a support shaft, an idler gear, a counter shaft, and a second gear. The input shaft is rotatably supported by the casing, and the first gear is fixedly supported by the input shaft. The support shaft is fixed to the casing, and the idler gear is rotatably supported by the support shaft. The counter shaft is rotatably supported by the casing, and the second gear is supported by the counter shaft via a synchromesh mechanism. The eye gear always meshes with the first gear and the second gear, respectively.

The support shaft has both end portions fixed to the casing and a gear support portion that rotatably supports the idler gear between the both end portions. The outer diameter of the gear support portion is at least 1/2 times the outer diameter of the idler gear defined to a predetermined size by the outer diameter position of the first gear, the outer diameter position of the second gear, and the axial position of the support shaft . The size is set .

  In the above configuration, the outer diameter of the gear support portion of the support shaft that supports the idler gear is 1/2 or more times the outer diameter of the idler gear, and the ratio of the outer diameter of the gear support portion to the outer diameter of the idler gear is increased. For this reason, the inertia moment of the idler gear is reduced, and the tooth strike excitation force of the idler gear is reduced. Therefore, gear rattling noise during idling can be reduced.

  According to the present invention, it is possible to reduce gear rattling noise during idle operation.

It is sectional drawing of the transmission of one Embodiment of this invention. It is a schematic diagram which shows arrangement | positioning of the reverse gear and eye door gear of FIG. FIG. 3 is a cross-sectional view taken along the direction of arrow III in FIG. 2. It is sectional drawing which shows a modification. It is sectional drawing which shows the comparative example whose outer diameter of a gear support part is less than 1/2 time of the outer diameter of an idler gear. It is a figure which shows an example of the rotation fluctuation | variation of an input shaft. It is a figure which shows an example of the tooth-gear excitation force of a 1st-speed gear. It is a figure which shows an example of the tooth-gear excitation force of a 2nd speed gear. It is a figure which shows an example of the tooth-gear excitation force of a reverse gear in the comparative example of FIG. It is a figure which shows an example of the tooth-gear excitation force of the idler gear in the comparative example of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional view of a transmission for a vehicle according to the present embodiment, FIG. 2 is a schematic view showing the arrangement of a reverse gear and an eye gear in FIG. 1, and FIG. 3 is a cross-sectional view taken in the direction of arrow III in FIG.

  The transmission 1 according to the present embodiment is a constantly meshing type in which corresponding gears always mesh with each other at any gear position (shift position), and is mounted on a large vehicle such as a truck. As shown in FIG. 1, in this transmission 1, the input shaft 2 and the output shaft 3 are arrange | positioned coaxially, and the countershaft 4 is arrange | positioned in parallel with them. The input shaft 2, the output shaft 3, and the counter shaft 4 are rotatably supported by the casing 5.

  In the casing 5, there are provided gear speeds (N1 to N4) from the first forward speed (N1) to the fourth speed (N4) and a reverse gear speed stage (R). The input shaft 2 and the counter shaft 4 are connected via respective gear speeds (N1 to N4, R). The counter shaft 4 and the output shaft 3 are connected by meshing between an output gear 6 fixedly supported on the counter shaft 4 and an output gear 7 fixedly supported on the output shaft 3. Drive rotation from the engine (not shown) is input to the input shaft 2 and transmitted to the counter shaft 4 via one of the gear speed stages (N1 to N4, R), and is output via the output gears 6 and 7. It is transmitted to the output shaft 3 and output from the output shaft 3.

  Of the forward gear speeds (N1 to N4), the first and second speed gear speeds (N1, N2) are fixedly supported by the input shaft 2 (first speed gears 11, 2nd speed). The gear 21) and the gear (first speed gear 12, second speed gear 22) supported by the countershaft 4 via the synchromesh mechanism 61 mesh with each other. In each of the synchromesh mechanisms 61 and 62, a claw of a synchronizer (not shown in the figure) fixed to the counter shaft 4 and a claw of a synchro cone (not shown in the figure) press-fitted into the side surfaces of the gears 12 and 22 are engaged. The countershaft 4 and the gears 12 and 22 are fixed by the engagement of these claws so that the power is transmitted.

  Of the forward gear speeds (N1 to N4), the third and fourth speed gear speeds (N3, N4) are gears (3) supported by the input shaft 2 via the synchromesh mechanisms 63, 64. The speed gear 31, the fourth speed gear 41) and the gear (the third speed gear 32, the fourth speed gear 42) fixedly supported by the counter shaft 4 mesh with each other. In each of the synchromesh mechanisms 63 and 64, a claw of a synchronizer (not shown) that is fixed to the input shaft 2 and a claw of a synchro cone (not shown) that are press-fitted into the side surfaces of the gears 31 and 41 are engaged. The input shaft 2 and the gears 31 and 41 are fixed by the engagement of these claws, and the power is transmitted.

  As shown in FIGS. 1 to 3, at the reverse gear speed (R), the reverse gear (first gear) 51 and the idler gear 50 are engaged, and the idler gear 50 and the reverse gear (second gear) 52 are engaged. . The reverse gear 51 is fixedly supported on the input shaft 2, and the reverse gear 52 is supported on the counter shaft 4 via a synchromesh mechanism 65. The idler gear 50 is rotatably supported by a support shaft 70, and the support shaft 70 is fixed to the casing 5 via a support bracket 72. That is, the idler gear 50 is a simple idle gear that does not include a synchro cone. In the synchromesh mechanism 65, a claw of a synchronizer (not shown in the figure) fixed to the counter shaft 4 and a claw of a synchro cone (not shown in the figure) press-fitted into the side surface of the reverse gear 52 are detachably engaged with each other. The countershaft 4 and the reverse gear 52 are fixed by the engagement of these claws, and power is transmitted.

  As shown in FIG. 3, the support shaft 70 has both ends 70a fixed to a support bracket 72 having a U-shaped cross section, and a gear support that rotatably supports the idler gear 50 via the needle bearing 71 between the both ends 70a. Part 70b. The outer diameter Ds of the gear support portion 70b (and the inner diameter of the idler gear 50) is at least 1/2 times the outer diameter Dg of the idler gear 50 (Ds ≧ Dg / 2). For example, when the outer diameter Dg of the idler gear 50 is 200 mm, the outer diameter Ds of the support shaft 70 is set to 100 mm or more.

  The support shaft 70 of the present embodiment is generally cylindrical, and both end portions 70a and the gear support portion 70b have substantially the same diameter, but only the gear support portion 70b of the support shaft 70 is the outer diameter of the idler gear 50. What is necessary is just 1/2 times or more of Dg. Therefore, for example, as shown in FIG. 4, the outer diameter Ds of the gear support portion 70 b is formed to be ½ times or more of the outer diameter Dg of the idler gear 50, and both end portions 70 a are ½ times of the outer diameter Dg of the idler gear 50. You may form less.

  In the neutral state in which the gear position (shift position) is set to neutral by the shift operation of the shift lever (not shown) by the driver, the mesh between the synchronizer and the synchro cone is released in all the synchromesh mechanisms 61 to 65, Power is not transmitted. When the gear position is set to the forward gear stage or the reverse gear stage, the synchronizer and the synchro cone in the synchromesh mechanisms 61 to 65 corresponding to the shift operation among the gear speed stages (N1 to N4, R) Mesh with each other and power is transmitted through the synchromesh mechanism.

  During idle operation in which the gear position is neutral and the engine is idling, the meshing between the synchronizer and the synchro cone is released in all the synchromesh mechanisms 61-65. Accordingly, the gears 31, 32, 41 and 42 of the third and fourth gear gear stages (N3 and N4) do not rotate, and the gears of the first and second gear gear stages (N1 and N2). 11, 12, 21 and 22, and the reverse gears 51 and 52 and the idler gear 50 of the reverse gear speed (R) rotate.

  During idle operation, the rotational fluctuation component input to the transmission 1 becomes large, and therefore noise due to gear rattling (tooth rattling noise) may be excessive. As a method for suppressing the occurrence of rattling, it is effective to apply a rotational resistance to at least one of the gears that rotate while meshing with each other, and press the tooth surfaces by the rotational resistance.

  Here, with respect to the first and second gear speed stages (N1, N2), the respective synchro cones of the respective synchromesh mechanisms 61, 62 are provided so as to overlap in the axial direction. Thereby, rotational resistance is added to each gear 12 and 22, and gear rattling is suppressed.

  On the other hand, the idler gear of the reverse gear gear stage (R) is a simple idle gear that is not equipped with a synchro cone, and therefore, the gear is operated in the same manner as the gear speed stages (N1, N2) of the first speed and the second speed. Rotational resistance cannot be applied.

  For example, when the input shaft 2 fluctuates as shown in FIG. 6 during idle operation, the gears of the first and second gear gear stages (N1, N2) (first gears 11, 12, second gear 21 , 22) fluctuates as shown in FIGS. On the other hand, as shown in FIG. 5, when the idler gear 50 is rotatably supported by the support shaft 80 in which the outer diameter of the gear support portion 80 b is set to be less than ½ times the outer diameter of the idler gear 50, the reverse gear The tooth strike excitation force 51 and 52 and the tooth strike excitation force of the idler gear 50 vary as shown in FIGS. As apparent from the comparison between FIGS. 7 and 8 and FIGS. 9 and 10, when the outer diameter of the gear support 80b is set to be less than ½ times the outer diameter of the idler gear 50, the reverse gear 51, The tooth strike excitation force of 52 and the idler gear 50 is larger than the tooth strike excitation force of the first speed gears 11, 12 and the second speed gears 21, 22.

  In this regard, in this embodiment, the outer diameter Ds of the gear support portion 70b of the support shaft 70 that supports the idler gear 50 is equal to or greater than ½ times the outer diameter Dg of the idler gear 50. The ratio of the outer diameter Ds of the support part 70b is enlarged. Thus, by expanding the outer diameter Ds of the support shaft 70, the rigidity of the gear itself can be easily secured, the moment of inertia of the idler gear 50 is reduced, and the tooth striking excitation force of the idler gear 50 is reduced. The Therefore, gear rattling noise during idling can be reduced.

  As described above, the present invention has been described based on the above embodiment, but the present invention is not limited to the content of the above embodiment, and can be appropriately changed without departing from the present invention. is there.

  For example, the moment of inertia can be further reduced by appropriately selecting the material of the idler gear 50.

  The present invention can be widely applied to vehicle transmissions.

1: Transmission 2: Input shaft 3: Output shaft 4: Counter shaft 5: Casing 11, 12: 1st gear 21, 22: 2nd gear 31, 32: 3rd gear 41, 42: 4th gear 50: Idler gear 51 , 52: Reverse gear 61-65: Synchromesh mechanism 70: Support shaft 70a: Both ends of support shaft 70b: Gear support portion of support shaft 71: Needle bearing 72: Support bracket

Claims (1)

An input shaft rotatably supported by the casing; a first gear fixedly supported by the input shaft; a support shaft fixed by the casing; an idler gear rotatably supported by the support shaft; A counter shaft rotatably supported by the casing; and a second gear supported by the counter shaft via a synchromesh mechanism, wherein the eye door gear always meshes with the first gear and the second gear, respectively. Transmission gear structure,
The support shaft has both end portions fixed to the casing, and a gear support portion that rotatably supports the idler gear between the both end portions,
The outer diameter of the gear support portion is one of the outer diameters of the idler gear defined to a predetermined size by the outer diameter position of the first gear, the outer diameter position of the second gear, and the axial position of the support shaft. / Gear structure of transmission characterized in that it is set to be at least twice as large .

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