Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural elements selectively braked
Patent
1994-03-08
1996-04-23
Marmor, Charles A.
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural elements selectively braked
475336, 74378, 74665H, F16H 314
Patent
active
055098630
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a transmission device, especially for boat motors, comprising a pair of intersecting shafts, drivingly connected to each other by means of at least one pair of bevel gears, a reversing mechanism driven by said shafts and having hydraulically operated multi-disk clutch means, by means of which the rotational direction of an output shaft is reversible.
BACKGROUND OF THE INVENTION
In a transmission device, known now for many years, for boat motors, an input shaft drives via a double bevel gearing, an intermediate shaft, which in turn via an additional bevel gear mechanism, drives an output shaft, which can either be the propeller shaft itself or be provided with the flange intended to be coupled to a propeller shaft. The reversing mechanism is integrated into the bevel gear mechanism by it having two freely rotatably mounted bevel gears which can be automatically locked by means of clutch means to the intermediate shaft and which engage a bevel gear on the input shaft.
The clutch means used were inter alia cone clutches, comprising a double clutch cone displaceable on the intermediate shaft between the bevel gears, whereby the clutch cone is displaceable into engagement with a facing conical clutch surface on the respective bevel gear. The displacement of the clutch cone was achieved mechanically and special mechanical devices utilizing the rotation of the shaft were used to overcome the tendancy to self locking which occurs in such clutches and which can create problems with disengagement, especially at high motor torque.
There have recently been developed hydraulically operated multi-disk clutches for locking and releasing the gears in the reversing mechanism. Such an arrangement shown in EP-A-295 569. Two bevel gears on an input shaft are alternately engageable with the shaft to drive an output shaft, which has a bevel gear in engagement with the two gears on the input shaft. The halves of the clutch cooperating with the respective gears are integrated into a unit which is placed between the freely rotatably mounted gears, i.e. near the point of intersection of the rotational axis of the shafts. The use of hydraulically operated clutches instead of mechanically operated cone clutches makes it possible to control engagement smoothly even at very high power, thus eliminating the risk of self locking.
The design of the known multi-disk clutch as a double clutch placed between the releasable gears in the same place as the known cone clutches creates however problems. This is due to the fact that the arrangement requires more space in the axial direction than the cone clutch arrangement, and this means that the gears in the bevel transmission must be made with larger radial dimensions and this makes the entire transmission device with associated housing heavier, more expensive and more space consuming.
SUMMARY OF THE INVENTION
The purpose of the present invention is to achieve in a transmission device of the type described by way of introduction with multi-disk clutches, an arrangement which enables the entire transmission device to be made lighter, less expensive and more compact than the above described known transmission device. This is achieved according of the invention by virtue of the fact that the multi-disk clutch means are arranged on the side of at least one bevel gear facing away from the point of intersection between the rotational axis of the first mentioned shafts.
In such a transmission device, the clutch means are moved from a location where they interfere with the gears of the bevel gearing to a location outside the double bevel gearing, which means that they will not effect the dimensioning of the bevel gears. Thus they only need be dimensioned with regard to stresses, and in practice this will mean that their diameter can be substantially reduced compared with transmissions with the clutch between the double gears.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail below with reference to examples
REFERENCES:
patent: 4267749 (1981-05-01), Chambers et al.
patent: 4276034 (1981-06-01), Kashmerick
Hedlund Benny
M.ang.nsson Staffan
AB Volvo Penta
Kwon Peter
Marmor Charles A.
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