Machine element or mechanism – Elements – Gear casings
Patent
1998-01-09
1999-06-29
Marmor, Charles A.
Machine element or mechanism
Elements
Gear casings
137884, F16H 5702
Patent
active
059163330
DESCRIPTION:
BRIEF SUMMARY
The invention concerns an arrangement for sealing a hydraulic control device which is assembled on the underside of an automatic transmission. The electromagnetic actuators and hydraulic valves are in the hydraulic control device.
BACKGROUND OF THE INVENTION
By the expression automatic transmission, used in the preamble, is to be understood both stepped and continuously variable automatic transmissions. Electrohydraulic automatic transmissions are composed of the following units: a starting unit such as a hydrodynamic converter, clutch/brakes, a hydraulic control device and an electronic transmission control device. The electronic transmission control device forms, from the input variables, the parameters required for control of the automatic transmission. Input variables are signals prepared by sensors and signals made available by other electronic control devices such as the engine control device. The electronic transmission control device controls, via output signals, the electromagnetic actuators which are in the hydraulic control device. Gearshifts are initiated, via the electromagnetic actuators, by selecting an adequate clutch/brake combination. The pressure distribution during the gearshift and the pressure level outside the gearshift are additionally controlled by the electromagnetic actuators.
From the prior art, for example DE-OS 40 41 253, automatic transmissions are known where the hydraulic control device is assembled on the underside. The hydraulic control device consists of one intake snorkel, one valve housing, one intermediate plate with a seal and one channel plate. Here the channel plate and the transmission housing come into contact by two surfaces. These two surfaces are designed as sealing surfaces. As a result of the setting properties, a change of the pre-load force of the clamping bolts and leakage can occur in this place. Since the hydraulic control device can only be partly wetted by the lubricant pan, leakage results in that the pump, via the intake channel, sucks air from the interior of the transmission instead of sucking hydraulic fluid from the lubricant pan.
SUMMARY OF THE INVENTION
The problem to be solved by the invention is thus to ensure a reliable suction for the hydraulic control device.
According to the invention, the problem is solved by the channel plate having at least one intake channel, one main pressure channel, and measuring and distribution channels wherein the intake channel is surrounded at least partly by a distribution channel. The distribution channel holds a higher pressure level than the intake channel. The distribution channel is between the intake channel and the outer side of the channel plate. The advantage obtained by this solution, according to the invention, is that leakage at the channel plate/transmission housing site does not result in the suction of air. Since the intake channel is surrounded by a distribution channel with a higher pressure level, the leakage causes the intake channel to suck the hydraulic fluid from this distribution channel.
In another embodiment, it is proposed that the main pressure channel be at least partly surrounded by pressureless auxiliary channels situated between the main pressure channel and a measuring channel. The advantage of this embodiment is that an adulteration of the pressure level within the measuring channel, in the case of leakage, is effectively prevented. In the case of leakage, the hydraulic fluid reaches the pressureless auxiliary channels from the main pressure channel. The hydraulic fluid thus cannot reach the measuring channels.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment is shown in the drawings. They show:
FIG. 1 is an arrangement and a design of a hydraulic control device; and
FIG. 2 is a channel plate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows the arrangement and design of a hydraulic control device 12. This hydraulic control device is a component part of the automatic transmission 1 and is within the housing 2. The hydraulic control device 12 is secure
REFERENCES:
patent: 4210034 (1980-07-01), Younger
patent: 4805490 (1989-02-01), Fuehrer et al.
Battista Mary Ann
Marmor Charles A.
ZF Friedrichshafeh AG
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