JPS6141798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-speed transmission for a ship's propulsion system.

The thrust requirement curve (thrust vs. speed) for designing ships propelled by outboard motors or sterndrive propulsion units has a noticeable hump at the point where the ship begins to surface and plan. The propeller is usually the engine's rated RP
m (revolutions per minute) and the maximum speed of the ship, it is necessary to absorb all the power of the engine. Propellers of prior art dimensions normally limit engine rpm during this critical period. If the propeller is designed to force the boat to "go over the hump" under relatively high load conditions, such as when a water skier is being towed to the boat by a line, then the boat will rise above the water. This causes the engine to run at excessive speeds even though less power is required to drive the propeller.

This problem can be alleviated by using propellers with a suitable pitch, but despite many years of development efforts, it has not been possible to produce a practical and efficient variable pitch propeller.

Boat racing propulsion units are also automatically switched to help the boat's engines quickly reach full speed when accelerating into a turn and then return to full speed as the boat begins to rise above the water. It is desirable to have a transmission device that does this.

The invention is particularly suitable for marine propulsion systems, such as outboard motors or stern drive units, from a first gear ratio that allows the engine to run at high speeds while driving the driveshaft at low speeds without increasing the speed of the engine. A two-speed transmission is provided in which the drive shaft can be switched to a second gear ratio in which the drive shaft is driven at a higher speed.

More specifically, the present invention includes an input shaft adapted to connect to a power source, a drive shaft, and a first shaft mounted for rotation with the input shaft.
a second drive gear supported for rotation coaxially with and independent of the input shaft; and a second drive gear supported for rotation coaxially with the drive shaft and meshingly engaged with the first drive gear. a second driven gear supported for rotation with the drive shaft and arranged in meshing engagement with the second drive gear; The drive shaft rotates relative to the first driven gear when the driven gear is rotated in a first direction and the drive shaft is rotated at a speed greater than the rotational speed of the first driven gear. a first clutch device drivingly connects a first driven gear to the drive shaft to allow the first driven gear to rotate; and a second clutch device selectively drivingly connects the second drive gear to the input shaft for driving the second drive gear in response to rotation of the input shaft. a second clutch device for causing the shaft to then be rotated through the second drive and driven gears independently of the first and second drive and driven gears; 2, characterized in that the gear ratio of the second driven gear is greater than the gear ratio of the first drive gear to the first driven gear;
The present invention provides a variable speed transmission.

The present invention further provides a propulsion system for a ship including a lower unit and the above-described two-speed transmission. The drive shaft is rotatably supported by the lower unit and drivingly connected to a propeller shaft which is rotatably supported by the lower unit and supports a propeller.

According to one embodiment of the invention, the second clutch means for selectively connecting the second drive gear to the input shaft acts in response to actuation of the input shaft so that the input shaft reaches a speed above a predetermined speed. When rotated, drive coupling of the second drive gear to the input shaft automatically switches to a higher gear ratio.

According to another embodiment of the invention, the second clutch is a centrifugal clutch supported on the input shaft and acts in response to rotation of the second drive gear such that the speed of the second drive gear increases the speed of the input shaft. Means is included for drivingly coupling the second driven gear to the input shaft upon a speed equal to or greater than a predetermined speed.

One of the principal features of the present invention is to provide a marine propulsion system that includes a simple two-speed transmission that can be conveniently switched to higher gear ratios.

One of the principal features of the present invention is that the vessel includes a two-speed transmission which prevents the engine from overspeeding when the throttle is at full throttle and the vessel is at maximum speed when rising above the water. The purpose is to provide a propulsion device.

Another major feature of the present invention is to provide a marine propulsion system that includes a transmission that automatically switches between two different gear ratios when the engine is at a predetermined speed.

Another main feature of the invention is that the sets and sets of drive gears and driven gears are particularly suitable for use in marine propulsion systems and the like and drivingly connect a drive shaft to an input shaft. and a means for switching one set of gears to another set of gears.

Other features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings.

Before describing in detail the preferred embodiments of the invention, it is to be understood that this invention is not limited to the details of construction and arrangement of parts that are hereinafter described or shown in the accompanying drawings. . The invention is capable of other embodiments and of being carried out in various other ways. It is also to be understood that the terms used are for purposes of description and not limitation.

FIG. 1 shows a marine propulsion system, such as an outboard motor 10, which includes a power head 12 housing an internal combustion engine 14 and a lower unit 16 having a gear box 18. Rotatably supported within the gearbox 18 is a propeller shaft 20 which supports a propeller 22 at its outer end. Also positioned within the gear box 18 are a pair of opposing axially spaced gears 24, 26 supported and drivingly connected to the propeller shaft 20. A drive shaft 28 extends through the lower unit 16 and is rotatably mounted to the lower unit and includes gears 24, 26.
It supports the lower bevel gear 30 that meshes with the lower bevel gear 30. Drive shaft 28 is drivingly connected to engine 14 via a two-speed transmission, generally designated 32.

The transmission 32 includes an input shaft 34 rotatably supported by a bearing 35 and drivingly connected to the engine 14, a first drive gear 36 supported on the input shaft 34 for rotation therewith, and a first drive gear 36 coaxial with the input shaft 34. and a second drive gear 38 supported for rotation independently therefrom.

The transmission 32 also includes a first driven gear 40 that meshes with the first drive gear 36 and is supported for rotation coaxially with the drive shaft 28, and a second drive gear 3.
8 and a second driven gear 42 supported for rotation with the drive shaft 28 . For purposes described below, the gear ratio of second drive gear 38 to second driven gear 42 is greater than the first drive gear to first driven gear ratio.

The first driven gear 40 is connected to the drive shaft 28 by a suitable one-way clutch 44 disposed therebetween.
drive connection by means. Since the one-way clutch means 44 is constructed by methods of the prior art, a detailed description of its structural features and mode of operation is not deemed necessary for a full understanding of the present invention. Generally, one-way clutch means 44 is responsive to rotation of first driven gear 40 via first drive gear 36 and input shaft 34 to
is designed to drive in one direction. Furthermore, the one-way clutch means 44 is connected to the drive shaft 2.
8 is greater than or equal to the rotational speed of the first driven gear 40 in the same direction (i.e., when the drive shaft 28 overruns the first driven gear 40). It is made to rotate freely relative to the drive gear 40.

For example, the one-way clutch means 44 is drivingly connected to the first driven gear 40 and the drive shaft 28
and may include teeth or ears (not shown) drivingly engaged with corresponding teeth or ears provided on the drive shaft and disengaged from the gears or ears of the drive shaft in the event of an overrun. .

A centrifugal clutch is supported on the input shaft 34 and operates to drively connect a second drive gear 38 to the input shaft 34 in response to rotation of the input shaft 34 above a predetermined speed.

Although various arrangements may be used, the illustrated construction includes a clutch drum 4 having a cylindrical inner surface 50 and supported for rotation with the input shaft 34.
A centrifugal clutch 46 including 8 is provided. The clutch 46 is also drivingly coupled to the second drive gear 38 and supported by a clutch and shoe wheel 54 which is supported for rotation coaxially and independently of the input shaft 34 and is connected to two or more clutches. - Has a shoe 52. Clutch shoe master wheel 54 rotates clutch shoe 52 in response to rotation of second drive gear 38 to move clutch shoe 52 to an inward or retracted position spaced from clutch drum 48 and to a second drive. The gear 38 is arranged in a suitable manner to move radially between an outward or extended position in driving engagement with the inner surface 50 of the clutch drum when the gear 38 is rotated at a speed corresponding to the predetermined speed of the input shaft. ing.

Clutch shoe 52 is configured in any suitable manner to include an arcuate surface adapted to drivingly engage inner surface 50 of clutch drum 48 when clutch shoe stock 54 is rotated at a speed equal to the predetermined speed of the input shaft. It can be composed of The amount by which the clutch shoe 52 moves outward from the retracted position in response to the clutch shoe not rotating above a predetermined speed is limited by suitable means (not shown).

During operation, when the input shaft 34 is rotated at a low or intermediate speed, the drive shaft and thus the propeller 22 are rotated by the input shaft 34 to the first drive gear 36 and the first driven gear 40. It is driven via one-way clutch means 44. At this time, the second drive gear 38 is also driven by the second driven gear 42, but the clutch shoe original wheel 54 is connected to the clutch shoe 52.
is rotated at a speed lower than the predetermined speed at which it is moved radially outwardly to the extended position so that it is free to rotate relative to input shaft 34.

When the speed of the engine is increased to the point where the clutch shoe train is rotated above a predetermined speed, the clutch shoe 52
Driving engagement with an inner surface 50 of drum 48 drivingly connects second drive gear 38 to input shaft 34 . The second drive gear 38 then connects to the second driven gear 42
to drive.

Because the gear ratio between second drive gear 38 and second driven gear 42 is greater than the gear ratio between first drive gear 36 and first driven gear 40, drive shaft 28 is rotated at a speed greater than the rotational speed of the first driven gear 40 to disengage the one-way clutch means 44 so that the drive shaft 28 is free to rotate relative to the first driven gear 40.
Drive shaft 28 is then driven by input shaft 34 through centrifugal clutch 46, second drive gear 38, and second driven gear 42.

When the engine speed is reduced to the point where the rotational speed of the clutch shoe stock 54 is below a predetermined speed, the clutch shoe 52 returns to the retracted position (i.e., away from the clutch stock ram 48) and moves away from the clutch stock ram 48. This moves the second drive gear 38 away from the input shaft 34 to reduce the rotational speed of the drive shaft 28 to a speed at which the one-way clutch means 44 is reengaged. Drive shaft 28 is then driven by input shaft 34 through first drive gear 36, first driven gear 40 and one-way clutch means 44.

In such an arrangement, a relatively large propeller is used to create enough thrust to cause the ship to go over a "hump" in the thrust vs. speed curve when the ship is heavily loaded, for example while towing a water skier. It can be used, and the engine will not reach excessive speed even if the throttle is fully turned and the boat reaches its maximum speed after the boat has entered the planing state. That is, the engine 14 causes the propeller 22 to rotate at a low speed via the input shaft 34, the first drive gear 36, the first driven gear 40, and the one-way clutch means 36 while rotating at a high speed. It can generate enough power, or thrust, to get the ship over the "hump." Once the ship is in planing, i.e., on the water's surface, and requires less power than before to rotate the propeller 22 at maximum speed, the transmission 32 is connected to the second drive via the centrifugal clutch 46. Switching to a high gear ratio by gear 38 and second driven gear 42 prevents the engine from overspeeding even at full throttle and maximum boat speed. Therefore, a smaller, more economical engine is needed to tow a large load, a water skier, that would normally require a larger engine to get the boat over the "hump" and into trim to raise it above the water. Can be used.

Furthermore, the two-speed transmission 32 of the present invention can be advantageously used in a propulsion unit for boat racing. This transmission system allows the engine to move higher when accelerating after a turn.
Rapidly increase speed to rpm and then as the ship rises above the water it becomes suitable for operation at maximum speed. When a centrifugal clutch is used, as in the example shown in Figure 1, this switching can be done automatically without any effort from the driver, resulting in high lap speeds for the particular engine. It will be done.

FIG. 2 shows a second embodiment of the invention which includes various components of similar construction and arrangement to the embodiment shown in FIG. Therefore, common parts are given the same reference numerals.

The basic difference between the marine propulsion system 60 shown in FIG. 2 and the marine propulsion system 10 shown in FIG. 1 is that the propulsion system of FIG.
This means that two drive shafts are used.
Using two drives allows the use of smaller drive gears to provide the same power to the propeller, thus reducing the front-to-front area of the gearbox 18 or reducing the dimensions of the portion of the housing surrounding the top end of the drive shaft. It can be made smaller or both.

Positioned within the gearbox 18 in driving connection to the propeller shaft 20 is a pair of bevel gears 62 which may be integral elements as shown or separate gears. A first rotatably supported drive shaft 64 extends through the lower unit 16;
Similar to the drive shaft 28 shown in the figure, one of the gears 62
It supports a lower bevel gear 66 that meshes with the lower bevel gear 66.
A second drive shaft 68 rotatably supported through the lower unit 16 parallel to the first drive shaft 64 extends therethrough, the second drive shaft 68 meshing with the other of the gears 62 . It supports the bevel gear 70. The first and second drive shafts 64, 68 are drivingly connected to the engine by a two-speed transmission 32a which is essentially of the same construction and operates similarly to the transmission 32.
a indicates that the second driven gear 42a is the second driving gear 3
8 and also a third driven gear 72 supported on the upper end of the second drive shaft 68 for rotation therewith.

In operation, the first drive shaft 64 is driven by the input shaft 34 when the input shaft 34 is rotated at a low or intermediate speed.
drive gear 36, a first driven gear 40 and one-way clutch means 44. Second
The drive shaft 68 connects the first drive gear 36 and the first driven gear 40 by the input shaft 34 .
one-way clutch means 44 and second driven gear 4
2a and third driven gear 72 to rotate drive shafts 64, 68 and gears 66, 70 in opposite directions. The second drive gear 38 is similarly driven by the second driven gear 42a, but the clutch shoe master wheel 54 is faster than the speed at which the clutch shoe 52 is moved radially outward toward the extended position. Since it is rotated at a low speed, it rotates freely relative to the input shaft 34.

When the speed of the engine is increased to the point where the clutch shoe stock 54 is rotated above a predetermined speed, the clutch shoe 52 engages the clutch drum 48 and drives the second drive gear 38. A driving connection is made to the input shaft 34 to shift the transmission 32a as described above. The drive shafts 64, 68 then connect to the input shaft 34.
The centrifugal clutch 46 and the second drive gear 38
, the second driven gear 42a, and the third driven gear 7
2. When the engine speed is reduced, the transmission switches back to the lower gear ratio as described above.

Although a centrifugal clutch is illustrated and described and is preferred as it automatically switches, it is also contemplated by the present invention to use any suitable manually switchable clutch to selectively couple the second driven gear 38 to the input shaft 34. It falls within the range of

Furthermore, although the transmission has been shown and described positioned within the power head directly below the engine, directly above the driveshaft, and at the top of the driveshaft, the transmission is located in the lower end portion of the driveshaft housing connected to the gearbox. It is also possible to position the lower unit above the gear box as in .

The two-speed transmission device of the present invention is compact and can be used in propulsion devices such as outboard motors that have a relatively limited capacity. Therefore, without increasing the size of the ship's propulsion system, the number of revolutions of the drive shaft, that is, the number of revolutions of the propeller, can be automatically changed between low speed and higher speed according to the load conditions of the ship's propeller. This provides a device that can change speeds.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a part of an outboard motor embodying various features of the present invention, with a part cut away and a cross section;
The figure is a side view, partially cut away, in cross section, of another embodiment embodying various features of the present invention. 10... Propulsion device, 16... Lower unit, 20...
Propeller shaft, 22... Propeller, 24, 2
6... Device for drivingly connecting the drive shaft to the propeller shaft, 28... Drive shaft, 32... Two-speed transmission, 36... First drive gear, second drive gear, 40... First driven gear, 42...Second driven gear, 46...First clutch device, 52...Second clutch device.

Claims (1)

[Claims] 1. An input shaft connected to a power source; a drive shaft; a first drive gear supported to rotate with the input shaft; coaxial with the input shaft and distinct from it; a second drive gear supported for independent rotation; a first driven gear supported for rotation coaxially with the drive shaft and arranged in meshing engagement with the first drive gear; a second driven gear supported for rotation with the drive shaft and arranged in meshing engagement with the second drive gear; drivingly coupling the first driven gear to the drive shaft to drive the drive shaft into the first drive gear; When the drive shaft is rotated in one direction through the gear and the first driven gear and the drive shaft is rotated in the one direction at a speed greater than the rotational speed of the first driven gear, the drive shaft rotates through the first driven gear. A first gear that allows rotation relative to the driven gear.
a clutch device for selectively drivingly coupling a second drive gear to the input shaft such that in response to rotation of the input shaft, the drive shaft is coupled to the first drive gear via the second drive gear and the second driven gear; a second clutch device adapted to rotate the first drive gear and the first driven gear in two directions independently of the first drive gear and the first driven gear; The gear ratio of the gear has a first value, and the gear ratio of the gear has a second value.
A two-speed transmission for a ship's propulsion system, characterized in that the gear ratio of the driving gear to the second driven gear is greater than a first value. 2. The second clutch device operates in response to the rotation of the input shaft to drively couple the second driven gear to the input shaft when the input shaft is rotated at a speed greater than a predetermined speed. A two-speed transmission for a ship's propulsion system according to claim 1. 3. The second clutch device is a centrifugal clutch supported by the input shaft and acts in response to rotation of the second drive gear by the second driven gear to cause rotation of the second driven gear. 3. A two-speed transmission for a marine propulsion system as claimed in claim 2, including means for drivingly connecting the second drive gear to the input shaft when the speed exceeds a speed equal to a predetermined speed. 4. A clutch drum in which the centrifugal clutch is supported to rotate with the input shaft, a plurality of clutch shoes, and a clutch supported in rotation with the second drive gear and independent of the input shaft. a clutch shoe wheel, the clutch shoe wheel supporting the clutch shoe and acting in response to rotation of the second drive gear to move the clutch shoe from a retracted position spaced from the clutch drum; A two-speed transmission for a ship's propulsion system as claimed in claim 3, wherein the clutch shoe is rotatably driven to move the clutch shoe radially outward into an extended position in which it meshes with the drum. Device.