JP2841549B2 - Transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission, and more particularly, to a transmission having a plurality of gear stages that can be selectively established between an input shaft and an output shaft. The present invention relates to a transmission having a main transmission mechanism and an auxiliary transmission mechanism having an extremely low gear train for lowering the speed of the main transmission mechanism to a lower speed.

2. Description of the Related Art A vehicle transmission generally has four to five forward gears and one reverse gear. For example, in an all-wheel drive vehicle, particularly an off-road vehicle, an emergency escape gear is used. For such purposes, there is a demand for an extremely low speed which is lower than the lowest forward speed (first speed).

In order to obtain such an extremely low speed, a sub speed change mechanism for an extremely low speed is conventionally provided in a transmission case separately from a main speed change mechanism having a normal speed. For example, Japanese Patent Laying-Open No. 58-85725 discloses a transmission having such a subtransmission mechanism. FIG. 3 shows the structure of the transmission mechanism described in this publication. In this transmission, the auxiliary transmission mechanism 20 composed of an extremely low-speed gear train is arranged coaxially with another gear train that constitutes the main transmission mechanism in an extension on the input shaft and the output shaft.

[Problems to be Solved by the Invention] In the gear train of the subtransmission mechanism, it is necessary to increase the gear ratio because the rotation speed of the input shaft is greatly reduced and transmitted to the output shaft. However, it is difficult to increase only this gear ratio due to the restriction on the distance between the input shaft and the output shaft, and it is generally difficult to obtain a large reduction ratio necessary for emergency escape or the like.

Further, in the case of the above-mentioned publication, the input and output shafts are extended and the auxiliary transmission mechanism is disposed thereon, so that the overall length of the transmission in the axial direction becomes large. In particular, the engine is arranged laterally at the front of the vehicle body. In such a vehicle, there is a disadvantage that the clearance between the transmission mechanism and the front wheel suspension mechanism cannot be sufficiently secured. In addition, increasing the overall length in the axial direction in order to add a subtransmission mechanism at an extremely low speed stage also requires the compatibility of members such as input / output shafts with a transmission that does not have a subtransmission mechanism. Not good.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transmission with a sub-transmission mechanism that does not require an increase in axial dimension in view of the above-mentioned problems.

Further, the present invention provides a transmission with an auxiliary transmission mechanism having a sufficiently large reduction ratio at an extremely low speed without increasing the inter-axis dimension between input and output shafts. It is an object of the present invention to provide a transmission in which parts are interchangeable with each other.

It is a further object of the present invention to provide a transmission that can reduce the number of parts as much as possible when adding a subtransmission mechanism, and thus can suppress an increase in weight.

[Means for Solving the Problems] The object of the present invention is to provide a gear train having a plurality of speed stages that can be selectively established between an input shaft and an output shaft, and the gear train is supported integrally on the input shaft. A main transmission mechanism including at least a first gear and a second gear or a gear rotating integrally with the second gear that is rotatably supported on the input shaft through a disengaging means. And a sub-transmission mechanism having an extremely low speed gear train for lowering the speed of the main transmission mechanism to a lower speed. In the transmission, the sub-transmission mechanism is supported on the sub-shaft and the sub-shaft. Third and fourth gears, and switching means for integrally rotating the third gear and the fourth gear when the very low-speed gear train is selected, wherein the third gear is connected to the first gear. A torque is transmitted, and the second gear is transmitted to the fourth gear. It is achieved by a fast mechanism.

[Operation] When the extremely low speed gear train is selected, the switching means rotationally integrally connects the third gear and the fourth gear, and is included in the speed gear train of the main transmission mechanism and integrated with the input shaft. The first gear that rotates at the same time drives the third gear supported by the countershaft, and also drives the fourth gear that rotates integrally with the third gear via the switching means. At this time, the second gear meshing with the fourth gear is separated from the input shaft via the engagement / disengagement means, so that the second gear rotates on the input shaft independently of the input shaft. An output that rotates a driven gear that forms a gear train of a main transmission mechanism that meshes with a second gear that forms a gear train of the mechanism or a gear that rotates integrally with the second gear, and rotates integrally with the driven gear. Rotate the shaft. Thus, the rotation of the input shaft is transmitted to the output shaft at a predetermined extremely low speed ratio.

Although only two gears are added as the auxiliary transmission mechanism,
These two gears are meshed with the two gears of the main transmission mechanism, respectively, and one of them drives the driven gear as a driving gear of the gear train of the main transmission mechanism, so that three-step shifting is possible after all. .

When the countershaft is rotatably supported with respect to the transmission case, one of the third and fourth gears can be rotated integrally with the countershaft, and the other can be bearing-supported on the countershaft. When the gear is fixedly supported on the transmission case, it is necessary to rotatably support both gears on the countershaft.

Embodiment A transmission according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional development view of the transmission of this embodiment.

In FIG. 1, an input shaft 11 to which torque is transmitted from a clutch 41 is connected to a transmission case 51 of a clutch housing 50.
And are supported by bearings. The output shaft 13 is arranged in parallel with the input shaft 11, and is similarly supported by the clutch housing 50 and the transmission case 51. Input shaft 11 and output shaft 13
Between the first and second speed gear trains G1, G2, G3, G3.
A fourth speed gear train G4, a fifth speed gear train G5, and a reverse gear train Gr are provided. Each drive gear G1a of the first and second gear trains,
G2a is rotatably supported on the input shaft, and the third to fifth drive gears G3a to G5a are rotatably supported on the input shaft via bearings. On the other hand, the driven gears G1b, G2b of the first and second speed gear trains are rotatably supported on the output shafts via bearings, respectively, and the driven gears G3b of the third to fifth speed gear trains.
G5b are supported integrally with the output shaft 13 in a rotating manner.

Between the driven gear G1b of the first speed gear train and the driven gear G2b of the second speed gear train, there is provided a synchronizing device (disengaging means) 52 for coupling either of the two adjacent gears to the output shaft. , Third gear train and fourth gear train, drive gears G3a, G4a
A synchronizer 53 for selectively coupling these to the input shaft is similarly arranged, and a synchronizer 54 for selectively coupling this to the input shaft is also adjacent to the drive gear G5a of the fifth speed gear train. Is arranged.

The sub-shaft 12 of the sub-transmission mechanism constituting the extremely low speed is arranged such that the center of each of the input shaft 11 and the output shaft 13 is a vertex of a triangle when viewed from the axial direction. In this embodiment, the sub shaft 12 is supported by the clutch housing 50 and the transmission case 51 via bearings, like the input shaft 11 and the output shaft 13. Third gear 2 meshing with drive gear (first gear) G1a of first speed gear train G1 fixedly supported on input shaft 11
A fourth gear 2 is formed integrally with the countershaft 12, is rotatably supported on the input shaft, and meshes with a second gear 24 formed integrally with the drive gear G3a of the third speed gear train G3. Gear 23
The sub shaft 12 is rotatably supported via a bearing. The drive gear G3a of the third speed gear train integral with the second gear meshes with the driven gear G3b of the third speed gear train to form a third speed gear train in the main transmission mechanism. A switching means (synchronizer) 31 is disposed on the countershaft adjacent to the fourth gear.
When the extremely low speed is selected, the countershaft 13 and the fourth gear are rotationally integrated with each other.

Drive gear (first gear) G1a, second gear 2 of first speed gear train
4, both the third gear 22, the fourth gear 23, and the third gear train G3
The a, G3b and the synchronizer 31 collectively constitute the extremely low speed gear train 20.

In the transmission of the embodiment configured as described above, for example, when the first speed gear train of the main transmission mechanism is selected, the synchronizer 52 rotates the driven gear G1b and the output shaft 13 of the first speed gear train G1. Join together. Thus, the rotation of the input shaft 11 driven by the rotation of the clutch 41 is transmitted to the output shaft 13 via the first speed gear train G1, and the output gear 28, which rotates integrally with the output shaft, meshes with the output gear 28. And transmitted to the drive shaft 43 via the ring gear 29 and the differential 42. At this time, the third gear 22 meshing with the first gear G1a also rotates and the countershaft also rotates at the same time, but this rotation is not transmitted to the fourth gear.

Next, when the extremely low speed is selected, the third gear 2 driven by the rotation of the first gear G1a rotating integrally with the input shaft 11 is set.
2 and the rotation of the countershaft 12 formed integrally therewith are transmitted to the fourth gear via the synchronizer 31 and are formed integrally with the second gear 24 meshing therewith. Drive gear G3a of the third speed gear train G3. The rotation of the drive gear G3a of the third speed gear train is transmitted to the driven gear G3b of the third speed gear train, which constitutes the third speed gear train, and is transmitted to the output shaft 13 which integrally supports the rotation. The drive shaft 43 is transmitted through the output gear 28, the ring gear 29, and the differential 42.
At very low speed.

The auxiliary transmission mechanism according to the present invention can perform three-stage shifting between the first gear and the third gear, between the fourth gear and the second gear, and between the driving gear and the driven gear of the third speed gear train of the main transmission mechanism. Thus, a large reduction ratio required for an extremely low speed can be achieved. In this embodiment, for example, the reduction ratio between the first gear G1a and the third gear 22 is 2.8, and the reduction ratio between the fourth gear 23 and the second gear 24 is 1.
3. If the reduction ratio of the third speed gear train is selected as 1.1, the overall reduction ratio will be about 4.0, and a reduction ratio of about twice the reduction ratio 2.0 of the first speed gear train will be possible. By variously selecting the reduction ratio between the respective gears, a reduction ratio of about 5 is possible without difficulty.

FIG. 2 shows a modification of the subtransmission mechanism of the embodiment shown in FIG. 1, in which the switching means is constituted by a sliding mesh gear. When the extremely low speed stage is selected in FIG. 2, the fourth gear 23, which is spline-coupled to the countershaft 12, moves from the position shown by the broken line to the position shown in FIG. And mesh with the second gear 24.

In the above-described embodiment, an example is shown in which the second gear 24 and the drive gear G3a of the third gear train are separate gears formed integrally, but the present invention is not limited to this, and both gears are not limited to this. Can be the same.

[Effects of the Invention] In the configuration of the present invention, a sub-transmission mechanism constituting an extremely low speed shift stage includes a first gear and a second gear or a second gear or a gear rotating integrally with a main transmission mechanism, and a sub-shaft. A third gear driven by a first gear rotating integrally with the input shaft and supported on a countershaft, and a second gear that can be selectively and integrally rotated with the input shaft via an engaging and disengaging means. A fourth gear driven and supported on the countershaft, and switching means for rotatingly coupling the third gear and the fourth gear when a very low gear train is selected;
In spite of the fact that the auxiliary transmission mechanism has only one additional shaft, the auxiliary transmission mechanism is composed of gears that mesh with the gear train of the main transmission mechanism. Since the transmission can be shifted, a transmission with an auxiliary transmission mechanism that is extremely compact in the axial and radial directions and has a sufficiently large reduction ratio as an extremely low speed stage can be provided.

Further, with the above configuration, it is possible to reduce the number of components, suppress an increase in weight, and achieve a transmission with an auxiliary transmission mechanism that is compatible with a transmission having no auxiliary transmission mechanism.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional development view showing the structure of a transmission having an auxiliary transmission mechanism at an extremely low speed, according to one embodiment of the present invention. FIG. 2 is a modified example of the auxiliary transmission mechanism shown in FIG. FIG. 3 is a longitudinal sectional view showing the structure of a conventional transmission with a subtransmission mechanism. (Description of Signs) G1 to G5; First to Fifth Speed Gear Train of Main Transmission Mechanism G1a; Drive Gear of First Speed Gear Train (First Gear) G2a to G5a; Second Speed to Fifth Speed Gear Drive gears G1b to G5b in each row; driven gears in first to fifth gear trains 11; input shaft, 12; sub shaft 13; output shaft, 20; extremely low-speed gear mechanism 22; third gear , 23; fourth gear 24; second gear 31; switching means (synchronizing device) 52-54;

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-80326 (JP, A) JP-A-61-236948 (JP, A) JP-A-61-36538 (JP, A) JP-A-61-36538 17748 (JP, A) JP-A-61-99743 (JP, A) JP-A-60-175722 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 3 / 00-3 / 42

Claims (1)

(57) [Claims] An input shaft and an output shaft are provided with a plurality of gear stages of a plurality of speed stages that can be selectively established, and the gear train is rotatably integrated with a first gear supported on the input shaft via a disengaging means. A main transmission mechanism including at least a second gear that is rotatably supported by the input shaft so as to be rotatable on the input shaft or a gear that rotates integrally with the second gear, and a speed lower than the lowest speed of the main transmission mechanism. And a sub-transmission mechanism having an extremely low-speed gear train, the auxiliary transmission mechanism comprising: a sub-shaft; third and fourth gears supported on the sub-shaft; Switching means for integrally rotating the third gear and the fourth gear when the is selected, wherein the third gear is transmitted with a rotational force to the first gear, and the second gear is A transmission mechanism, wherein a rotational force is transmitted to a fourth gear.