Machine element or mechanism – Elements – Gear casings
Patent
1997-10-20
1999-03-09
Wright, Dirk
Machine element or mechanism
Elements
Gear casings
74335, F16H 5704
Patent
active
058786309
DESCRIPTION:
BRIEF SUMMARY
The invention concerns an electronic control for transmissions of motor vehicles.
BACKGROUND OF THE INVENTION
Electronic systems for the control of the gearshift cycles are being increasingly used in mechanical transmissions. It is advantageous that the electronic system be accommodated on or in the transmission. The electronics is, of course, here exposed to extreme environmental conditions.
German Utility Model No. G 93 07 228 has disclosed a transmission control which is mounted within the transmission housing. The control here can be surrounded by transmission oil and radiate heat to the oil via cooling elements. The cooling of the control is essentially assumed by the transmission oil. In this arrangement, damage to the transmission control can only be rectified when the transmission is removed and dismounted from the vehicle. This requires an enormous after-sale expense which is in no proportion to the exchange of eventually inexpensive parts. The electronic system is constantly surrounded by aggressive transmission oil which, in case of damage to the seal or paint, results in an interruption in operation of the electronics.
SUMMARY OF THE INVENTION
Therefore, the invention is based on the problem of providing a transmission control where cooling of the electronics is reliable and simplified.
The electronic system of the transmission control of an automatic or automated transmission is mounted outside the transmission housing. Here it is advantageously in the area of the control means for actuating the transmission. Especially hydraulic or pneumatic actuators, preferably operated by fluids, belong to said control means. In the case of pneumatic actuators, they are supplied with compressed air from a compressed-air tank according to a control for actuating transmission elements. In the case of hydraulic actuators, this is accordingly done with hydraulic oil from an oil tank. Air is preferably used as a control fluid, but the following considerations can also be correspondingly applied to hydraulic actuators, an adapted seal has to be provided and, if needed, a cooler for the hydraulic oil.
During operation of a pneumatic actuator having two chambers, air is introduced in one chamber and an adjusting piston, which separates the two chambers of the actuator, is moved so as to force out the air from the other respective chamber. Said air is used, according to the invention, to cool the electronics. Both the forced out exhaust air and the control air flowing in can be used.
Three kinds of air actuation for cooling are distinguished: to be cooled separately or as whole; through them; and electronics so that heat from the electronic parts, separately or as whole, can be transmitted to said cooling plate.
In the first and second cases, the heat is eliminated by the blown in or blown through air. In the second case, the cooling plate first absorbs the heat and then radiates it to the air that flows past.
The moment of the air flow can be dealt with, separately or combined in different ways: the pneumatic actuators; measured temperature after exceeding a limit temperature; and eliminate accumulated heat.
The continuous air flow feed, according to point 1, is regulated via a throttle device. A temperature-dependent supply, according to point 3, is effected via temperature-controlled gearshift devices which, if needed, ensure a forced air supply, for example, via ventilators. In point 4, a forced air supply is likewise effected, for example, via ventilators.
By means of a heat-insulating barrier layer, the electronic parts can be insulated, relative to the other controller or also other adjacent parts of the transmission, so as to interrupt the transmission of heat in a direction toward the electronic parts.
BRIEF DESCRIPTION OF THE DRAWING(S)
The invention is described in detail with the aid of the figures. They show:
The invention is described in detail with the aid of the figures. They may show:
FIG. 1 a vehicle transmission with a mounted controller;
FIG. 2 a digrammatic controller with blown in air
REFERENCES:
patent: 5165468 (1992-11-01), Tajima et al.
patent: 5277663 (1994-01-01), Lemme et al.
patent: 5662007 (1997-09-01), Starker et al.
patent: 5678461 (1997-10-01), Stine
patent: 5811747 (1998-09-01), Taniguchi et al.
Birkenmaier Gerhard
Fessler Bernhard
Schwarz Josef
Kwon Peter T.
Wright Dirk
ZF Friedrichshafen AG
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