A negative-pressure balance system for a gearbox of a centrifugal compressor includes the gearbox, a hermetically-sealed low-level oil collecting tank and a U-shaped negative-pressure balance pipe. The gearbox is connected to a respirator, and the back pressure of the respirator is a local ambient atmospheric pressure. The bottom of the gearbox and the low-level oil collecting tank are connected by an oil conduit. An oil demister communicated with the low-level oil collecting tank is mounted at the top of the low-level oil collecting tank. The oil demister at least includes a ventilation device. The respirator is communicated with a front-end lubricating point in the gearbox. One end of the U-shaped negative-pressure balance pipe is communicated with the respirator, and the other end of the U-shaped negative-pressure balance pipe is communicated with a rear-end lubricating point in the gearbox.

An assembly for a compartment of a gas turbine engine that includes a housing, a gear, and a baffle disposed about the gear. The baffle includes an upstream portion and a downstream portion. The upstream portion includes an upstream inner wall and an upstream outer wall separated from the gear. The upstream inner wall is positioned between the upstream outer wall and the gear. An upstream flow channel is formed between the upstream inner wall and the upstream outer wall. The downstream portion of the baffle includes a downstream inner wall and a downstream outer wall separated from the gear. The downstream inner wall is positioned between the downstream outer wall and the gear. A downstream flow channel is formed between the downstream outer wall and the downstream inner wall.

A gas turbine engine comprises a fan drive turbine for driving a gear reduction. The gear reduction drives a fan rotor. A lubrication system supplies oil to the gear reduction. The lubrication system includes a lubricant pump supplying a mixed air and oil to a deaerator inlet. The deaerator includes a separator that for separating oil, and delivering separated air to an air outlet, and for delivering separated oil back into an oil tank. The separator includes a member having lubricant flow paths on both of two opposed sides. A method of designing a gas turbine engine is also disclosed.

An aircraft engine having an oil circuit and a transmission that can be supplied with oil via the oil circuit. Oil fed to the transmission can be directed out of the transmission into an oil reservoir, from which oil can be introduced directly back into the transmission via a hydraulic line path. According to the invention, the oil fed to the oil reservoir can only be fed to the hydraulic line path below a defined filling level of the oil reservoir. When the defined filling level of the oil reservoir is reached, oil can also be introduced into a further hydraulic line path.

A gas and liquid separation system could be said to have a passage with an inlet connected to receive a mixed gas and liquid flow. An air separation tube extends into the passage at a location downstream of where the inlet is connected with an upstream tube end upstream in the passage relative to a downstream tube end. The upstream tube end provides an obstruction to the mixed gas and liquid flow, to cause separation of the gas from the mixed gas and liquid flow. A liquid tube is connected to the passage at a location downstream of the air separation tube.

An oil supply system for supplying oil to a lubricating cavity of a gas turbine engine, the oil supply system has: a de-oiler having a de-oiler air-oil inlet, a de-oiler oil outlet hydraulically connected to the lubricating cavity, and a de-oiler air outlet in fluid flow communication with an environment outside of the oil supply system; and a closed-loop oil circuit including a main pump having a main pump inlet and a main pump outlet, the main pump outlet hydraulically connected to the lubricating cavity, a de-aerator having a de-aerator inlet hydraulically connected to a scavenge outlet of the lubricating cavity, a de-aerator air-oil outlet in fluid flow communication with the de-oiler inlet, and a de-aerator oil outlet hydraulically connected to the main pump inlet.

An oil reservoir assembly includes a tank, a return passage, a pressurization valve, a first passage, and a vent valve. The tank includes a canister, a fill port, an first oil outlet, an second air outlet, and an inlet. The inlet is disposed in the canister and is connected to a restrictor. The return passage is connected to the inlet of the tank and to a scavenge pump. The pressurization valve is fluidly connected to the second air outlet of the tank. The first passage is connected to the pressurization valve and to an accessory gearbox of the engine. The vent valve is disposed in the return passage and includes a body, a channel extending through the body, an inlet orifice, and an outlet orifice. The inlet orifice is disposed in an end of the body. The outlet orifice is fluidly connected to the inlet orifice via the channel.

An oil tank assembly for a gas turbine engine may include an oil tank having an upper compartment and a lower compartment. A baffle may separate the upper compartment of the oil tank from the lower compartment of the oil tank. A de-aerator may be included, where the de-aerator includes an oil inlet, a de-aerator outlet, and an air vent. The de-aerator may be configured to separate air from oil in an air-oil mixture such that the oil flows through the de-aerator outlet and such that the air flow through the vent. Further, the de-aerator may include a fill port for receiving oil.

A gas and liquid separation system could be said to have a passage with an inlet connected to receive a mixed gas and liquid flow. An air separation tube extends into the passage at a location downstream of where the inlet is connected with an upstream tube end upstream in the passage relative to a downstream tube end. The upstream tube end provides an obstruction to the mixed gas and liquid flow, to cause separation of the gas from the mixed gas and liquid flow. A liquid tube is connected to the passage at a location downstream of the air separation tube.

A hydraulic tank for a machine is disclosed herein. The hydraulic tank includes a casing defining an interior space and having an outer surface, an inner surface opposite the inner surface, and a return hydraulic fluid inlet extending through the casing. A first concave member is connected to the inner surface of the casing to form a passage. The passage is positioned and shaped to transport hydraulic fluid from the return hydraulic fluid inlet to another location within the hydraulic tank.