Information
-
Patent Grant
-
6401560
-
Patent Number
6,401,560
-
Date Filed
Thursday, June 29, 200024 years ago
-
Date Issued
Tuesday, June 11, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 074 3375
- 074 378
- 074 379
- 074 4731
- 074 47327
- 192 51
- 192 93 R
- 440 75
-
International Classifications
- F16H5902
- F16H6338
- B63H2308
-
Abstract
A shift mechanism of an outboard engine has a shift cam which is remotely-operable to effect change-over of the direction of rotation of a propeller shaft in a gear case. A shift cam support member is a member separate from and detachably secured to the gear case. The shift mechanism permits use of a single design of the gear case adapted to either a rotary shift cam or a vertically-movable shift cam.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shift mechanism of an outboard engine.
2. Description of the Related Art
A conventional outboard engine has a shift mechanism which is remotely-operable to change the direction of rotation of a propeller shaft between “forward” and “reverse” passing through a “neutral” state in the process. To enable such a change-over of direction of rotation, the propeller shaft has a push rod incorporated therein. The push rod is moved back and forth to bring a shift dog into and out of engagement with the propeller shaft. This arrangement is generally known as a “shift-in and shift-out” structure. A shift cam is typically used as means for effecting the back-and-forth movement of the push rod.
The shift cam has a cam profile which is defined by three curved recesses that are smoothly connected one to another. These three recesses correspond to three shift positions, i.e., the “forward”, “reverse” and “neutral” states, of the shift mechanism. The above-mentioned push rod is normally spring-biased towards the cam, so as to rest in one of the three recesses, thus selecting one of the three shift positions.
There are two types, of the shift cam: a vertically-movable shift cam which moves up and down to bring different recesses into engagement with the push rod; and a rotational shift cam which rotates within a horizontal plane. The rotational shift cam imparts to the operator a better feel of manipulation and is used mainly for large-sized outboard engines.
The shift cam is supported by a shift cam support portion which is disposed in, and formed integrally with, a gear case, regardless of the type of the shift cam.
The rotational shift cam and the vertically-movable shift cam have different structures and, hence, require different designs of the shift cam supporting structure. This means that one design of the gear case cannot be used commonly both for the rotational shift cam and the vertically-movable shift cam, due to the difference of the design of the shift cam supporting structure which is formed integrally with the gear case. Thus, manufacturers are obliged to prepare two types of gear case of different designs. This in turn requires troublesome work for the administration of the gear cases in the production process.
For instance, the following problems are encountered due to the difference between the two types of the shift cam. A vertically-movable shift cam is generally provided with a link mechanism in an engine room covered by an engine cover. It may be impossible to find space for accommodating such a link mechanism within the engine room, due to, for example, a change in the design specifications of the outboard engine. One solution to this problem could be to replace the vertically-movable shift cam with a rotational shift cam which does not require any link mechanism such as that used for the vertically-movable shift cam. This solution, however, imposes additional cost due to the necessity for a gear case which is designed exclusively for the rotary shift cam.
In general, the shift cam supporting portion is formed on the innermost portion of a gear case. This makes it difficult to mount and demount the shift cam.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a shift mechanism of an outboard engine which permits the use of a single type of gear case either with a vertically-movable shift cam or a rotational shift cam.
To this end, according to the present invention, there is provided a shift mechanism of an outboard engine, comprising: a remotely-operable shift cam for effecting change-over of the direction of rotation of a propeller shaft within a gear case; and a shift cam support member disposed in the gear case and detachably secured to the gear case and supporting the shift cam.
The shift cam support member may be a forward gear bearing housing for holding a bearing which supports a forward driven gear.
Alternatively, the shift cam support member may be a shift cam housing which is a member formed separately from and detachably secured to the gear case.
The shift mechanism may further comprise a detent mechanism provided on the shift cam support member.
The shift mechanism may also further comprise a bearing which is provided in the shift cam housing and which supports a shift rod for rotating the shift cam.
Preferably, the shift cam mechanism has been assembled by inserting the shift cam housing together with the shift can mounted therein, forwardly into the gear case and detachably securing the shift cam housing to the gear case.
The above and other objects, features and advantages of the present invention will become clear from the following description of a preferred embodiment with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a side view of an outboard engine incorporating an embodiment of the shift mechanism of the present invention, as viewed from the port side, with certain internal elements shown in dashed line.
FIG. 2
is an enlarged sectional view of a gear case used in the embodiment of FIG.
1
.
FIG. 3
is a sectional view taken along the line III—III of FIG.
2
.
FIG. 4
is an enlarged sectional view of a gear case used in a second embodiment of the present invention.
FIG. 5
is an enlarged sectional view of a gear case used in a third embodiment of the present invention.
FIG. 6
is an illustration of the gear case of
FIG. 5
as viewed in the direction of an arrow VI.
FIG. 7
is an enlarged sectional view of a gear case used in a fourth embodiment of the present invention.
FIG. 8
is an illustration of the gear case of
FIG. 7
as viewed in the direction of an arrow VIII.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
Referring first to
FIG. 1
an outboard engine, shown generally at
1
, has an engine holder
2
on which is mounted an engine unit
3
. The engine unit
3
is a so-called vertical engine with a crankshaft
4
extending substantially vertically.
An oil pan
5
is disposed beneath the engine holder
2
. A clamp bracket
6
, attached to the engine holder
2
for example, clamps to a transom of the boat's hull (not shown), whereby the outboard engine
1
is secured to the hull. The engine unit
3
and the engine holder
2
are covered by an engine cover
7
.
A drive shaft housing
8
is provided below the oil pan
5
. A drive shaft
9
extends substantially vertically through the engine holder
2
, oil pan
5
and the drive shaft housing
8
. The drive shaft
9
is connected at its upper end to the lower end of the crankshaft
4
. The drive shaft
9
extending downward through the drive shaft housing
8
drives, through bevel gears
11
disposed in a gear case
10
under the drive shaft housing
8
and through a propeller shaft
12
, a propeller
13
which propels a boat or the like.
The outboard engine
1
is provided with a remote-controlled shift mechanism
14
in the four embodiments of the invention. The embodiments are detailed in
14
A (first embodiment of FIG.
3
),
14
B (second embodiment of FIG.
4
),
14
C (third embodiment of FIG.
5
), or
14
D (fourth embodiment of FIG.
7
). The remote-controlled shift mechanism
14
effects change-over of the direction of rotation of the propeller shaft
12
from “forward” to “reverse” via a “neutral” state, and vice versa.
Referring now to
FIGS. 2 and 3
, the shift mechanism
14
A of this embodiment has major parts including a shift rod
15
, a shift rod
16
, an assist device
17
, a shift cam
18
A, a push rod
19
and a shift dog
20
. This shift mechanism is a rotary-type mechanism which effects the change-over of the shift position through horizontal rotation of the shift cam
18
A.
The shift rod
15
extends towards the gear case
10
from, for example, a position in the engine cover
7
near the engine unit
3
. The shift rod
15
is connected to the shift rod
16
via an assist device
17
which is disposed in the portion of the gear case
10
adjoining the drive shaft housing
8
and which incorporates a detent mechanism
21
. When an operator on board manipulates a shift lever (not shown) or the like, the motion of the shift lever is converted into a rotational motion of the shift rod
15
which is then transmitted to the shift rod
16
.
The shift cam
18
A is fixed to the lower end of the shift rod
16
to rotate together with the shift rod
16
. As will be seen from
FIG. 3
, the shift cam
18
A has a cam profile composed of three consecutive curved recesses
22
which respectively correspond to the “forward” (F), “neutral” (N) and the “reverse” ®) shift positions. These recesses have bottoms that are at different radial directions from the axis of rotation of the shift cam
18
A. The push rod
19
is received in a bore formed in the propeller shaft
12
, so as to be movable in the direction of the axis of the propeller shaft
12
. The push rod
19
is always biased by a spring
23
against the shift cam
18
, so that the end of the push rod
19
is urged into one of the recesses
21
of the shift cam
18
A, whereby the shift mechanism
14
is set to one of the three shift positions.
The aforementioned bevel gears
11
include a forward driven gear
24
and a reverse driven gear
25
which are rotatably carried by the propeller shaft
12
through bearings
26
and
27
. These driven gears
24
and
25
are always held in driving engagement with a drive gear
28
fixed to the lower end of the drive shaft
9
. The shift dog
20
on the outer peripheral portion of the propeller shaft
12
drivingly connects either one of the forward driven gear
24
and the reverse driven gear
25
to the propeller shaft
12
, while disconnecting the other from the same, in accordance with the axial position of the push rod
19
. The shift dog
20
also holds the shift mechanism
14
in the neutral state in which both the forward and reverse driven gears
23
and
24
are freed from the propeller shaft
12
.
As will be seen from
FIGS. 2 and 3
, the bearing
26
which supports the forward driven gear
24
of the bevel gears
11
is held by a forward gear bearing housing
29
A which is a supporting member detachably secured to the gear case
10
. Likewise, the bearing
27
which supports the reverse driven gear
25
of the bevel gears
11
is held by a reverse gear bearing housing
30
which is detachably secured to the gear case
10
. The forward gear bearing housing
29
A has an integral support portion
31
A which supports the shift cam
18
A.
Referring now to
FIG. 4
, a shift mechanism
14
B of the second embodiment has major components such as a shift rod (not shown), a shift rod
16
, a shift cam
18
B, a push rod
19
and a shift dog
20
. This shift cam mechanism is a vertical-motion-type mechanism in which the shift cam
18
B is moved up and down.
The shift cam
18
B is integrally attached to the lower end of the shift rod
16
. The shift cam
18
B has a rear face which includes a can profile having three consecutive recesses
22
. An end of the push rod
19
engage one of the three recesses
22
of the shift cam
18
B as the shift cam
18
B is moved up or down.
The bearing
26
, which supports the forward driven gear
24
of the bevel gears
11
, is held by a forward gear bearing housing
19
B which is a support member detachably secured to the gear case
10
. Likewise, the bearing
27
which supports the reverse driven gear
25
of the bevel gears
11
is held by a reverse gear bearing housing
30
which is detachably secured to the gear case
10
. The forward gear bearing housing
29
B includes an integrally formed support portion
31
B which supports the shift cam
18
B. The support portion
31
B is provided with the detent mechanism
21
.
The detent mechanism
21
provided means for holding the shift cam
18
B in the neutral position. For instance, the detent mechanism
21
may include a rigid ball
33
which is urged by a spring
34
into a recess
32
the front side of the shift cam
18
B.
Referring now to
FIGS. 5 and 6
, the shift mechanism
14
C of the third embodiment is a rotary-type mechanism which is similar to the shift mechanism
14
A of the first embodiment. The embodiment of
FIGS. 5 and 6
differs from the first embodiment in the following respects. In the first embodiment, the bearing
26
in support of the forward driven gear
24
of the bevel gears
11
is held by the forward gear bearing housing
29
A which is detachably secured to the gear case
10
, and the support portion
31
A for supporting the shift cam
18
A is integrally formed on the forward gear bearing housing
29
A. In contrast, in the shift mechanism of the third embodiment, the bearing
26
in support of the forward driven gear
24
fits in a mating portion
35
formed in the gear case
10
integrally therewith, while the shift cam denoted by
18
C is supported by a shift cam housing
36
C which is a support member formed as a member separate from the gear case
10
.
For instance, the arrangement may be such that the shift cam housing
36
C is inserted toward the front into the gear case
10
through a shaft hole
37
formed in a rear part of the gear case
10
and is detachably secured to the gear case by means of, for example, bolts
38
.
The shift cam housing
36
C is inserted into the gear case
10
after the shift cam
18
C is mounted in the shift cam housing
36
C. After the insertion and fixation of the shift cam housing
36
C, the shift rod
16
is inserted downward into the gear case
10
and is connected to the shift cam
18
C. The shift cam housing
36
C is provided therein with a bearing
39
that supports the shift rod
16
.
Referring now to
FIGS. 7 and 8
, a shift mechanism of the fourth embodiment, denoted by
14
D, is of the vertical-motion-type mechanism which is similar to shift mechanism
14
B of the second embodiment.
The fourth embodiment is distinguished from the second embodiment in the following respects. In the second embodiment, the bearing
26
in support of the forward driven gear
24
of the bevel gears
11
is held by the forward gear bearing housing
29
B which is detachably secured to the gear case
10
, and the support portion
31
B for supporting the shift cam
18
B is integrally formed on the forward gear bearing housing
29
B. In contrast, in the shift mechanism of the fourth embodiment, the bearing
26
in support of the forward driven gear
24
fits in a mating portion
35
formed in the gear case
10
integrally therewith, while the shift cam denoted by
18
D is supported by a shift cam housing
36
D which is a support member formed as a member separate from the gear case
10
.
For instance, the arrangement may be such that the shift cam housing
36
D is inserted forwardly into the gear case
10
through the shaft hole
37
formed in a rear part of the gear case
10
and is detachably secured to the gear case by means of, for example, bolts
38
.
When the shift cam housing
36
D is inserted into the gear case
10
, the shift cam
18
D has been mounted in the shift cam housing
36
D. After the insertion and fixation of the shift cam housing
36
D, the shift rod
16
is inserted downward into the gear case
10
and is connected to the shift cam
18
D. The shift cam housing
36
D is provided with a detent mechanism
21
which is similar to that used in the second embodiment.
A description will now be given of the operations of the illustrated embodiments.
An operator of a boat manipulates a shift lever (not shown) of, for example, the shift mechanism
14
A of the first embodiment (FIG.
2
), so that the shift rod
15
and, hence, the shift rod
16
are rotated, thereby rotating the shift cam
18
A fixed to the lower end of the shift rod
16
. As a result of the rotation of the shift cam
18
A, the end of the push rod
19
that has been held in engagement with one of the recesses
22
is caused to engage another recess
22
adjacent to the first-mentioned recess
22
. Since the radial distances of the bottoms of these recesses
22
from the axis of rotation of the shift cam
18
are different, the push rod
19
is moved within the propeller shaft
12
along the axis of the propeller shaft, thereby selectively connecting one of the bevel gears
11
with the propeller shaft or disconnecting these bevels gears
11
from the propeller shaft.
In the first embodiment as described, as well as in the second embodiment, the forward gear bearing housing
29
A (
29
) for holding the bearing
26
in support of the forward driven gear
24
of the bevel gears
11
is detachably secured to the gear case
10
, and the support portion
31
A (
311
B) for supporting the shift cam
18
A (
18
B) is integrally formed on the forward gear bearing housing
29
A (
29
B). With this arrangement, a single gear case
10
can be adapted for either of the two different types of the shift cam, i.e., the rotational shift cam and the vertically-movable shift cam, simply by replacing the forward gear bearing housing
29
A (
29
B).
In the third embodiment as described, as well as in the fourth embodiment, the bearing
26
in support of the forward driven gear
24
fits in the mating portion
35
formed in the gear case
10
integrally therewith, and the shift cam
18
C (
18
D) is supported by the shift cam housing
36
C (
36
D) which is formed as a member separate from the gear case
10
. With this arrangement, a single gear case
10
is adapted for either of the two different types of the shift cam, i.e., the rotational shift cam and the vertically-movable shift cam, simply by replacing the shift cam housing
36
C (
36
D).
As will be understood from the foregoing description, according to the present invention, different types of the shift cam (rotational shift cam and vertically-movable shift cam) are easily assembled with the same design of he gear case
10
, because the shift cam
18
A(
18
B,
18
C,
18
D) is supported by a shift cam support member, i.e., the forward gear bearing housing
29
A(
29
B) or the shift cam housing
36
C(
36
D), which is prepared as a member separate from the gear case
10
and detachably secured to the gear case
10
.
This eliminates the necessity for the two different types of gear case
10
which hitherto have been necessarily prepared corresponding to two types of shift cams
18
A,
18
C and
18
B,
18
D. Thus, the manufacturers are required to prepare only one type of the gear case and, hence, can save the cost that has been incurred for the molding of two types of the gear case. At the same time, it becomes unnecessary to assign two different parts numbers that have been employed to enable identification of the two types of gear case. This also eliminates the necessity for two different storage spaces for the gear case, thus facilitating storage and administration of the gear cases.
As stated before, a problem occurs when the space inside the engine room is reduced by a change in the design specifications of the outboard engine
1
, so that the space for accommodating a link mechanism (not shown) associated with the vertical-motion-type shift cam
18
B(
18
D) is not available in the engine room. This problem, however, is easily overcome by the present invention which permits replacement of the vertical-motion-type shift cam
18
B(
18
D) with a rotary shift cam
18
A(
18
C) simply by the replacement of the forward gear bearing housing
29
A(
29
B) or the shift cam housing
36
C(
36
D). This effectively serves to reduce the production cost.
Furthermore, in accordance with the present invention, a member which is separate from and detachably secured to the gear case
10
, i.e., the forward gear bearing housing
29
A(
29
B) or the shift cam housing
36
C(
36
D), supports the shift cam
18
A(
18
C) or
18
B(
18
D). This simplifies the arrangement of cores of the mold for molding the gear case
10
, thus contributing to further reduction in the production cost.
Referring specifically to the third and fourth embodiments, the assembly of the shift mechanism is facilitated and the time required for the assembly work is shortened, because the shift mechanism can be completed by forwardly inserting the shift cam housing
36
C(
36
D) together with the shift cam
18
C(
18
D) mounted therein and fixing the shift cam housing
36
C(
36
D) to the gear case
10
, through the shaft hole
37
formed in the rear part of the gear case
10
, followed by the insertion and connection of the shift rod
16
to the shift cam
18
C(
18
D) from the upper side of the gear case
10
.
In the third embodiment as described, the shift cam housing
36
C which is in support of the rotary shift cam
18
C is provided therein with the bearing
39
for supporting the shift rod
16
. This ensured smooth rotation of the shift rod
16
, as well as rigidity of the supporting structure, thus offering better feel of the shifting operation.
In the second embodiment, as well as in the third embodiment, the shift cam
18
B(
18
C) can stably be set in the neutral position with a good click feel, by virtue of the detent mechanism
21
which is provided on the support portion
31
B of the forward gear bearing housing
29
B supporting the vertically-movable shift cam
18
B, or on the shift cam housing
36
D which supports the vertically-movable shift cam
18
D.
Although in the third and fourth embodiments the shift cam housing
36
C(
36
D) is inserted into the gear case
10
through the shaft hole
37
formed in the rear portion of the gear case
10
, this is not exclusive and the shift mechanism may be assembled by inserting the shift cam housing
36
C(
36
D) downward into the gear case
10
, through the top end opening of the gear case
10
at which the gear case
10
is adjoined to the drive shaft housing
8
.
As will be understood from the foregoing description, in accordance with the present invention, there is provided a shift mechanism of an outboard engine, comprising: a remotely-operable shift cam for effecting change-over of the direction of rotation of a propeller shaft within a gear case; and a shift cam support member disposed in the gear case and detachably secured to the gear case and supporting the shift cam, the shift cam support member being, for example, a forward gear bearing housing for holding a bearing which supports a forward driven gear, or a shift cam housing which is a member formed separately from and detachably secured to the gear case. With this arrangement, a single design of the gear case can easily be adapted to different types of the shift cam, i.e., a rotational shift cam or a vertically-movable shift cam. This contributes to the reduction in the production cost, while simplifying and facilitating the work for storing the gear cases, as well as the administration of the assembly process.
In a preferred form of the present invention, the shift mechanism further comprises a detent mechanism provided on the shift cam support member. This ensures that the shift mechanism is stably set to and held in the neutral state with good feel of click.
The shift mechanism can further have a bearing which is provided in the shift cam housing and which supports a shift rod for rotating the shift cam. The bearing offers an improved feel in the shifting operation.
Preferably, the shift cam mechanism has been assembled by inserting the shift cam housing together with the shift can mounted therein, forwardly into the gear case and detachably securing the shift cam housing to the gear case. This assembly process improves the efficiency of the assembly work, while shortening the time required for the assembly.
Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
Claims
- 1. A shift mechanism of an outboard engine comprising:a gear case; a remotely-operable shift cam for effecting change-over of a direction of rotation of a propeller shaft within said gear case; a shift cam support member disposed in said gear case and detachably secured to said gear case and supporting said shift cam; and said shift cam support member includes a forward gear bearing housing for holding a bearing which supports a forward driven gear.
- 2. A shift mechanism of an outboard engine according to claim 1, wherein said shift cam support member comprises a shift cam housing which is a member formed separately from and detachably secured to said gear case.
- 3. A shift mechanism of an outboard engine according to claim 1, further comprising a detent mechanism on said shift cam support member.
- 4. A shift mechanism of an outboard engine comprising:a gear case; a remotely-operable shift cam for effecting change-over of a direction of rotation of a propeller shaft within said gear case; a shift cam support member disposed in said gear case and detachably secured to said gear case and supporting said shift cam; and a detent mechanism on said shift cam support member.
- 5. A shift mechanism of an outboard engine comprising:a gear case; a remotely-operable shift cam for effecting change-over of a direction of rotation of a propeller shaft within said gear case; a shift cam support member disposed in said gear case and detachably secured to said gear case and supporting said shift cam; said shift cam support member including a shift cam housing which is a member formed separately from and detachably secured to said gear case; and a bearing in said shift cam housing and said bearing supporting a shift rod for rotating said shift cam.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-280757 |
Sep 1999 |
JP |
|
US Referenced Citations (8)
Foreign Referenced Citations (3)
Number |
Date |
Country |
09216600 |
Aug 1997 |
JP |
10-114299 |
May 1998 |
JP |
11165695 |
Jun 1999 |
JP |