Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-02-01
2002-01-01
Marmor, Charles A (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06334367
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a parallel shaft transmission, in which a plurality of gear trains are provided to connect a plurality of shafts that are disposed parallel with one another, and a plurality of clutching means are provided each to be engaged selectively with a corresponding one of the gear trains to establish a power transmission path.
BACKGROUND OF THE INVENTION
Such parallel shaft transmissions are widely used in automobiles. For example, an automatic transmission with five speed ratios has been disclosed in Japanese Laid-Open Patent Publications No. 4 (1992)-331852 (A), No. 5 (1993)-272601 (A) and No. 7 (1995)-19295 (A).
In this transmission, a plurality of gear trains are arranged over a plurality of shafts which are disposed in parallel with one anther, and these gear trains are disposed axially parallel with one anther. In addition, a plurality of clutches are provided each close to a respective gear train for the purpose of selecting that specific gear train for mechanical power transmission. Because of this arrangement, generally, the axial dimension of the transmission is relatively large. This tendency of the transmission having a large axial dimension becomes more prominent as the number of available speed ratios is increased in the design of the transmission. Especially, automatic transmissions are prone to acquiring a large size because they typically include hydraulic clutches, whose dimensions in radial direction as well as in axial direction are relatively large.
Nowadays, transmissions which are used in automobiles are equipped with a large number of speed ratios to improve drive performance, and the number of speed ratios has increased from three to four. Now, a transmission with five speed ratios is coming to be practical, so the size of the transmission is becoming a serious problem because the transmission, which has such a large number of speed ratios, acquires a correspondingly large size. In the automatic transmission with five speed ratios which has been disclosed in the above mentioned publications, various ideas are applied in the arrangement of the gears and the clutches to minimize the size of the transmission.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a parallel shaft transmission which incorporates a large number of speed ratios in a construction designed as compact as possible by contriving an arrangement for integrating gears and clutches.
In order to achieve this objective, the present invention provides a parallel shaft transmission comprising a first input shaft, a second input shaft, and a counter shaft, which are disposed parallel with one another. This transmission further comprises at least one set of first speed ratio gear train (for example, the fifth speed gear train
25
a
and
25
b,
the fourth speed gear train
24
a
and
24
b
and the reverse gear train
26
a,
26
b
and
26
c
of the following embodiment shown in FIG.
3
), at least one first clutching means (for example, the fifth speed clutch
15
and the fourth speed clutch
14
of the embodiment shown in FIG.
3
), at least one set of second speed ratio gear train (for example, the second speed gear train
22
a
and
22
b,
the LOW gear train
21
a
and
21
b
and the third speed gear train
23
a
and
23
b
of the embodiment shown in FIG.
3
), at least one second clutching means (for example, the second speed clutch
12
, the LOW clutch
11
and the third speed clutch
13
of the embodiment shown in FIG.
3
), and a connection gear train. Each set of first speed ratio gear train includes a first speed ratio drive gear (for example, the fifth speed drive gear
25
a,
the fourth speed drive gear
24
a
and the reverse drive gear
26
a
of the embodiment shown in
FIG. 3
) which is disposed on the first input shaft and a first speed ratio driven gear (for example, the fifth speed driven gear
25
b,
the fourth speed driven gear
24
b
and the reverse driven gear
26
c
of the embodiment shown in
FIG. 3
) which is disposed on the counter shaft, with the first speed ratio drive gear and the first speed ratio driven gear meshing with each other. The first clutching means is disposed on the first input shaft, and it connects and disconnects the first speed ratio drive gear rotationally to and from the first input shaft, respectively. Each set of second speed ratio gear train includes a second speed ratio drive gear ( for example, the second speed drive gear
22
a,
LOW drive gear
21
a
and third speed drive gear
23
a
of the embodiment shown in
FIG. 3
) which is disposed on the second input shaft and a second speed ratio driven gear (for example, the second speed driven gear
22
b,
the LOW driven gear
21
b
and the third speed driven gear
23
b
of the embodiment shown in
FIG. 3
) which is disposed on the counter shaft, with the second speed ratio drive gear and the second speed ratio driven gear meshing with each other. The second clutching means is disposed on the second input shaft, and it connects and disconnects the second speed ratio drive gear rotationally to and from the second input shaft, respectively. The connection gear train is used for power transmission from the first input shaft to the second input shaft through a gear (for example, the second and third connection gears
32
and
33
of the embodiment shown in
FIG. 3
) on an idle shaft which is disposed parallel with the first input shaft.
In this parallel shaft transmission, the drive power which is input from the engine to the first input shaft can be transmitted through the connection gear train directly to the second input shaft. As the speed ratio gear trains are disposed between the first input shaft and the counter shaft as well as between the second input shaft and the counter shaft, the axial length of the transmission is relatively short, so the transmission is made compact. Also, because the connection gear train includes a gear which is disposed on an idle shaft, the distance between the first input shaft and the second input shaft is adjustable as desired. Therefore, the clutching means which comprise hydraulic clutches, whose dimensions in radial direction are relatively large, do not interfere with each other even though the first clutching means, which is disposed on the first input shaft, and the second clutching means, which is disposed on the second input shaft, are positioned substantially on a common plane which is perpendicular to the shafts. There is a high degree of freedom in the arrangement of the clutching means. As a result, the first and second speed ratio gear trains and the first and second clutching means are arranged appropriately to construct the transmission in a relatively small size.
It is preferable that the connection gear train comprise a first connection gear which is mounted on the first input shaft, a second connection gear and a third connection gear which are disposed on the idle shaft and a fourth connection gear which is mounted on the second input shaft. In this case, the first connection gear meshes with the second connection gear; the second connection gear and the third connection gear rotate together as a unified body; and the third connection gear meshes with the fourth connection gear. In this construction, only the second and third connection gears, which rotate together as a unified body, are provided on the idle shaft. Thus, bearings can be disposed adjacent to these gears to support the idle shaft so as to restrict deformation of the idle shaft, which deformation may otherwise occur during the power transmission under a heavy load. Therefore, the meshing of the connection gears which are supported by the idle shaft is not affected from changes in the load of the transmission. As a result, the noise of the meshing is controlled to a relatively low level. Furthermore, because the design is such that the first connection gear meshes with the second connection gear while the third connection gear meshes with the fourth connection gear, the tooth surfaces which are located on one s
Asatsuke Shouji
Hatakeyama Kazuma
Marmor Charles A
Pang Roger
LandOfFree
Parallel shaft transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Parallel shaft transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Parallel shaft transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2871947