Transmission for a marine outboard propulsion system

Abstract

A transmission (6) for a marine outboard propulsion system (1) which comprises an input shaft (7) connectable to an engine (4), a countershaft (19) arranged parallel to the input shaft (7), several pairs of gears (15, 16; 17, 18) for transmitting rotation of the input shaft (7) to the countershaft (19) and switching elements (23, 25, 30) for selectively engaging gears (15, 16, 17, 18, 38) to enable at least two forward gear ratios and one reverse gear ratio. The transmission (6) comprises an output shaft (8) which is arranged coaxial to the input shaft (7) and a PTO countershaft (31) adapted to drive at least one PTO-aggregate (9, 10). The transmission is part of a marine outboard propulsion system.

Claims

1. A transmission, for a marine outboard propulsion system, comprising: an input shaft for connection to an engine, a countershaft being arranged parallel to the input shaft, several pairs of gears for transmitting rotation of the input shaft to the countershaft, and switching elements for selectively engaging gears to enable at least two forward gear ratios and one reverse gear ratio, wherein the transmission comprises an output shaft which is arranged coaxial to the input shaft and a power take-off countershaft adapted to drive at least one power take-off assembly, and the transmission comprises a reverse gear shaft which is arranged parallel to the input shaft and which is in a constant driving connection with the input shaft, and the power take-off countershaft is in a constant driving connection with the reverse gear shaft.

2. The transmission according to claim 1, wherein the power take-off countershaft is arranged parallel to the input shaft.

3. The transmission according to claim 1, wherein the transmission comprises a first power take-off drive shaft which is coupled to the power take-off countershaft by a first bevel gear mechanism.

4. The transmission according to claim 3, wherein the transmission comprises a second power take-off drive shaft which is coupled to the power take-off countershaft by a second bevel gear mechanism.

5. The transmission according to claim 1, wherein a first disc carrier of a first friction clutch is fixed to the input shaft and a reverse disc carrier of a reverse friction clutch is fixed to the reverse gear shaft, a first reverse gear is rigidly arranged at the first disc carrier and constantly meshing with a second reverse gear which is rigidly arranged at the reverse disc carrier.

6. The transmission according to claim 5, wherein at least one of: the first reverse gear is formed integrally with the first disc carrier, and/or the second reverse is formed integrally with the reverse disc carrier.

7. The transmission according to claim 5, wherein the transmission comprises a first fixed gear which is rotationally fixed to the countershaft, and the first fixed gear constantly meshes with a first idler gear mounted on the input shaft and with a reverse idler gear mounted on the reverse gear shaft.

8. A marine outboard propulsion system, comprising: an engine, a transmission comprising: an input shaft for connection to an engine, a countershaft being arranged parallel to the input shaft, several pairs of gears for transmitting rotation of the input shaft to the countershaft, and switching elements for selectively engaging gears to enable at least two forward gear ratios and one reverse gear ratio, wherein the transmission comprises an output shaft which is arranged coaxial to the input shaft and a power take-off countershaft adapted to drive at least one power take-off assembly, and the transmission comprises a reverse gear shaft which is arranged parallel to the input shaft and which is in a constant driving connection with the input shaft, the power take-off countershaft is in a constant driving connection with the reverse gear shaft, and a first hydraulic pump being drivable connected to a first power take-off drive shaft.

9. The marine outboard propulsion system according to claim 8, wherein the marine outboard propulsion system further comprises a second hydraulic pump drivable connected to a second power take-off drive shaft.

10. A transmission, for a marine outboard propulsion system, comprising: an input shaft for connection to an engine, a countershaft being arranged parallel to the input shaft, at least two pairs of gears for transmitting rotation of the input shaft to the countershaft, and at least two switching elements for selectively engaging gears to enable at least two forward gear ratios and one reverse gear ratio, wherein the transmission comprises an output shaft which is arranged coaxial to the input shaft and a power take-off countershaft adapted to drive at least one power take-off assembly, and the transmission comprises a reverse gear shaft which is arranged parallel to the input shaft and which is in a constant driving connection with the input shaft, and the power take-off countershaft is in a constant driving connection with the reverse gear shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following detailed description of a preferred embodiment of the invention in connection with the accompanying drawings will help to understand the objects, features and advantages of the invention, wherein:

(2) FIG. 1 shows a schematic plan of a marine outboard propulsion system according to the invention;

(3) FIG. 2 shows a schematic plan of a transmission for a marine outboard propulsion system according to the invention;

(4) FIG. 3 shows a schematic power flow diagram of the transmission in FIG. 2 and

(5) FIG. 4 shows a schematic plan of the transmission in FIG. 2 with a different arrangement of the bevel gear mechanisms at the PTO drive shafts.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a marine outboard propulsion system 1 which is mounted at the stern of a boats hull 2 in its operating position, with the water surface 3 as a horizontal plane. The marine outboard propulsion system 1 comprises a combustion engine 4 with a vertically oriented crankshaft 5. Crankshaft 5 is connected to an input shaft 7 of the transmission 6 which is located beneath the engine 4.

(7) In another embodiment the engine 4 and the transmission 6 must not be directly adjacent to each other. There might be other parts of the propulsion system positioned between the engine and the transmission.

(8) Via an output shaft 8 the power is transmitted to a lower bevel gear 11, which drives a horizontally oriented propeller shaft 12 with the propeller 13. The input shaft 7 enters the housing 22 on its upper side and the output shaft 8 leaves the housing 22 on its lower side. The crankshaft 5, the input shaft 7 and the output shaft 8 are all positioned coaxially to each other in a vertical axis 14. This way a relatively slim design of the marine outboard propulsion system 1 is achieved. Attached to a housing 22 of the transmission 6 there are two PTO aggregates 9 and 10.

(9) FIG. 1 shows only the housing 22, the input shaft 7, output shaft 8 and the first and second PTO-aggregate 9 and 10 of the transmission 6. Other elements of the transmission 6 are shown in FIG. 2 and described in the following.

(10) A first idler gear 15 and a second idler gear 17 are rotatably supported on the input shaft 7. First idler gear 15 is meshing permanently with a first fixed gear 16 which is fastened to a countershaft 19 and second idler gear 17 is meshing permanently with a second fixed gear 18 which is also fastened to countershaft 19. Hence, the first idler gear 15 together with the first fixed gear 16 form a first pair of gears and the second idler gear 17 together with the second fixed gear 18 form a second pair of gears. The first pair of gears 15, 16 has a different gear ratio than the second pair of gears 17, 18 in order to establish a first and a second forward gear F1, F2 with different ratios.

(11) Countershaft 19 is arranged parallel to the input shaft 7. A third fixed gear 20 is also fastened to the countershaft 19 and in permanent meshing contact with a fourth fixed gear 21 which is fastened to output shaft 8. Output shaft 8 is arranged coaxially to the input shaft 7.

(12) A first friction clutch 23 and a second friction clutch 25 are arranged as switching elements on the input shaft 7 to enable the selection of a first and a second forward gear ratio. A first disc carrier 24 is fixed to the input shaft 7 and carries outer discs of the first and second friction clutch 23, 25 which are both formed as multi-disk clutches.

(13) The transmission 6 comprises further a reverse gear shaft 29 which is arranged parallel to the input shaft 7 and which is in a constant driving connection with the input shaft 7.

(14) A first reverse gear 26 is rigidly arranged at the outer side of the first disc carrier 24 and constantly meshing with a second reverse gear 28 which is rigidly arranged at the outer side of a reverse disc carrier 27. Said constant meshing between the first reverse gear 26 and the second reverse gear 28 is indicated in FIG. 2 by a dashed line between the two gears 26 and 28.

(15) The reverse disc carrier 27 is fixed to the reverse gear shaft 29 and is part of a reverse friction clutch 30. Hence, overall the transmission comprises three switching elements in form of friction clutches 23, 25 and 30 to selectively engage gears to enable two forward gear ratios and one reverse gear ratio. The first reverse gear 26 is formed integrally with the first disc carrier 24 and the second reverse gear 28 is formed integrally with the reverse disc carrier 27. A reverse idler gear 38 can be connected to the reverse gear shaft 29 by closing the reverse friction clutch 30. The reverse idler gear 38 is constantly meshing with first fixed gear 16 and so in constant driving connection with the countershaft 19 and the output shaft 8. Using the first fixed gear 16 for the reverse gear and for the first forward gear saves a separate fixed reverse gear on countershaft 19 helping thereby to fulfill narrow space requirements.

(16) The transmission comprises further a PTO countershaft 31 which is arranged parallel to the input shaft 7. The PTO countershaft 31 located inside the housing 22 and in a constant driving connection with the input shaft 7 via the reverse gear shaft 29. For this a fifth fixed gear 32 which is fastened to the reverse gear shaft 29 is permanently meshing with a sixth fixed gear 33 which is fastened to the PTO countershaft 31.

(17) The PTO countershaft 31 drives the first PTO-aggregate 9 and the second PTO-aggregate 10. The first PTO-aggregate 9 is driven via a first bevel gear mechanism 34 and first PTO drive shaft 35 while the second PTO-aggregate 10 is driven via a second bevel gear mechanism 36 and second PTO drive shaft 37. Each of the first and second bevel gear mechanisms 34 and 36 comprises a pair of bevel gears. Advantageous gear ratios for specific applications of the corresponding PTO-aggregate 9, 10 can be achieved by selecting appropriate pairs of bevel gears 34, 36 driving the corresponding PTO drive shaft 35, 37.

(18) The power flow diagram of FIG. 3 shows the power flow from the input shaft 7 to the output shaft 8 in the three different gears, namely the first forward gear F1 second forward gear F2 and reverse gear R.

(19) In order to engage the first forward gear F1 the first friction clutch 23 is closed while the second friction clutch 25 and the reverse friction clutch 30 are open. In this case the power flows from the input shaft 7 via the first friction clutch 23, first idler gear 15, first fixed gear 16, countershaft 19, third fixed gear 20 and fourth fixed gear 21 to the output shaft 8.

(20) In order to engage the second forward gear F2 the second friction clutch 25 is closed while the first friction clutch 23 and the reverse friction clutch 30 are open. In this case the power flows from the input shaft 7 via the second friction clutch 25, second idler gear 17, second fixed gear 18, countershaft 19, third fixed gear 20 and fourth fixed gear 21 to the output shaft 8.

(21) In order to engage the reverse gear R the first friction clutch 23 and the second friction clutch 25 are open while the reverse friction clutch 30 is closed. In this case the power flows from the input shaft 7 via the first reverse gear 26, second reverse gear 28, reverse clutch 30, reverse idler gear 38, first fixed gear 16, countershaft 19, third fixed gear 20 and fourth fixed gear 21 to the output shaft 8.

(22) The transmission 6 shown in FIG. 4 is very similar to transmission 6 shown in FIG. 2. That is why the same elements of the transmission have the same reference number in FIG. 2 and FIG. 4. The only difference of the transmission 6 in FIG. 4 is the arrangement of the bevel gear mechanisms 34 and 36 at the PTO counter shaft 31. By interchanging the drive side of the driving bevel gear related to the driven bevel gear at one or both bevel gear mechanisms 34, 36 the direction of rotation of the corresponding PTO drive shaft 35, 37 can be changed.

REFERENCE NUMERAL

(23) 1 marine outboard propulsion system 2 hull 3 water surface 4 engine 5 crankshaft 6 transmission 7 input shaft 8 output shaft 9 PTO-aggregate 10 PTO-aggregate 11 lower bevel gear 12 propeller shaft 13 propeller 14 vertical axis 15 first idler gear 16 first fixed gear 17 second idler gear 18 second fixed gear 19 countershaft 20 third fixed gear 21 fourth fixed gear 22 housing 23 first friction clutch 24 first disc carrier 25 second friction clutch 26 first reverse gear 27 reverse disc carrier 28 second reverse gear 29 reverse gear shaft 30 reverse friction clutch 31 PTO-counter shaft 32 fifth fixed gear 33 sixth fixed gear 34 first bevel gear mechanism 35 first PTO drive shaft 36 second bevel gear mechanism 37 second PTO drive shaft 38 reverse idler gear F1 first forward gear F2 second forward gear R reverse gear