192 clutches and power-stop control – Field responsive frictional media type
Patent
1988-04-29
1989-10-03
Braun, Leslie A.
192 clutches and power-stop control
Field responsive frictional media type
192113R, 192113B, F16D 3702, F16D 1372
Patent
active
048710490
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic-particle-type coupling device for transmitting the rotation of the crankshaft of an engine to a transmission, and particularly relates to the improvement of a means for cooling the driven body of the coupling device.
BACKGROUND ART
FIG. 1 shows a conventional magnetic-particle-type coupling device disclosed in the Japanese Patent Application (OPI) No. 60733/81 (the term "OPI" as used herein means an "unexamined published application"). Rotation whose speed is changed by a transmission 2 to which the coupling device 1 is connected is decelerated by the differential gear unit of a speed reducer 3 and then transmitted to axles. The magnetic-particle-type coupling device 1 comprises a driving body 4 constructed by conjoining two members to each other in the axial direction of the coupling device and secured to a driving plate 6 secured to a crankshaft 5; an excitation coil 7 housed in the opening of the driving body 4; a driven body 8 whose outside circumferential surface faces the inside circumferential surface of the driving body 4 across a gap and which is secured to a hub 11 supported by a bearing 10 to a bracket 9 attached to the driving body; magnetic particles 12 filled in the gap; a pair of slip rings 13 which are secured with an electric insulation bushing 15 to a cap 14 attached to the bracket 9 and are connected so as to supply electricity to the excitation coil 7; a brush unit 16 for supplying the electricity through the slip rings 13; and a coupling shaft 17 secured to the hub 11 and constituting the input shaft 17a of the transmission 2. A case 18 houses the coupling device 1 and the transmission 2. A temperature sensor 19 is secured to the portion of the case 18, which faces the coupling device 1. Shown at 20 and 21 in FIG. 1 are a ring gear and the output shaft of the transmission 2, respectively.
When the electricity is supplied to the excitation coil 7 as the driving body 4 is rotated by the crankshaft 5 after the starting of an engine, the magnetic particles 12 are magnetized to couple the driving body and the driven body 8 to each other to transmit the rotation of the driving body to the driven body to rotate the input shaft 17a of the transmission 2 through the coupling shaft 17. Between the input shaft 17a and output shaft 21 of the transmission 2, the speed of the rotation is changed among a low, a second, a third and a fourth speed stages by a plurality of speed change gear means between the input and the output shafts in response to the manipulation of a manual speed change lever. The rotation of the output shaft 21 is transmitted to wheels through the differential gear unit of the speed reducer 3 and the axles.
Since it is necessary to smoothly increase the coupling torque of the magnetic-particle-type coupling device 1 at the time of starting of a vehicle, a slip takes place between coupling members to generate heat to raise the temperature of the coupling device. If the rise in the temperature of the coupling device is large, the device burns. This is a problem.
To prevent the problem, the temperature sensor 19 is attached to the case 18 to supply a signal from the temperature sensor to a controller through a second speed stage switch which is turned on when the vehicle is started at the second speed stage of the transmission 2. When the second speed stage switch is turned on and the temperature in the case 18 has exceeded a limit due to the frequent repetition of the starting of the vehicle at the second speed stage of the transmission 2, the signal from the temperature sensor 19 is supplied to the controller to alter the electrical current of a clutch to shift the torque of the clutch to a level for a lower speed stage. As a result, the starting of the vehicle at the second speed stage of the transmission 2 is made impossible to suppress the rise in the temperature in the case 18 to prevent the coupling device 1 from burning.
However, since the temperature of the internal opening of the case 18 is detected by the temp
REFERENCES:
patent: 3481439 (1969-12-01), Finkin
patent: 3592298 (1971-07-01), Leffert
patent: 4611697 (1986-09-01), Okita et al.
"Selectroshift and Autoselectric Transmissions" in Automobile Engineer, Sep. 1957, pp. 2-10.
Braun Leslie A.
Mitsubishi Denki & Kabushiki Kaisha
Testardi David A.
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