Methods and systems are provided for adjusting an oil pressure supplied to an engine and a variable cam timing (VCT) responsive to a condition of the VCT system. In one example, a method may include adjusting the oil pressure based on engine speed, engine load, and engine oil temperature, and responsive to a request to shift the VCT system during specific engine operating conditions, increasing the oil pressure to an upper threshold oil pressure for the duration of the shift.

The present invention relates to a low-friction member imitating shark skin and a manufacturing method therefor, the low-friction member implementing a structure similar to shark skin and having riblets by stacking, in layers, composite particles formed by attaching spherical particles on the surfaces of plate-shaped particles, and thus the low-friction member has excellent low-friction characteristics. The present invention comprises: a base plate; plate-shaped particles stacked in layers on the surface of the base plate in the form of scales; and a plurality of spherical metal lubricating particles having a size smaller than that of the plate-shaped particles, and coated on the surfaces of the plate-shaped particles, wherein the metal lubricating particles are arranged in the form of a bridge connecting the base plate and the plate-shaped particles, and the plate-shaped particles to each other.

The present invention relates to a low-friction member imitating shark skin and a manufacturing method therefor, the low-friction member implementing a structure similar to shark skin and having riblets by stacking, in layers, composite particles formed by attaching spherical particles on the surfaces of plate-shaped particles, and thus the low-friction member has excellent low-friction characteristics. The present invention comprises: a base plate; plate-shaped particles stacked in layers on the surface of the base plate in the form of scales; and a plurality of spherical metal lubricating particles having a size smaller than that of the plate-shaped particles, and coated on the surfaces of the plate-shaped particles, wherein the metal lubricating particles are arranged in the form of a bridge connecting the base plate and the plate-shaped particles, and the plate-shaped particles to each other.

Methods and systems are provided for adjusting an oil pressure supplied to an engine and a variable cam timing (VCT) responsive to a condition of the VCT system. In one example, a method may include adjusting the oil pressure based on engine speed, engine load, and engine oil temperature, and responsive to a request to shift the VCT system during specific engine operating conditions, increasing the oil pressure to an upper threshold oil pressure for the duration of the shift.

An engine assembly includes a small air-cooled engine and a dry sump lubrication system including an external oil reservoir, wherein the dry sump lubrication system has an overall oil capacity that provides at least five hundred hours of engine oil life.

An engine assembly includes a small air-cooled engine and a dry sump lubrication system including an external oil reservoir, wherein the dry sump lubrication system has an overall oil capacity that provides at least five hundred hours of engine oil life.

A fracturing device, including a power unit, wherein the power unit comprises a muffling compartment, a turbine engine, an air intake unit, and a starter; the air intake unit is communicated with the turbine engine through an intake pipe, and configured to provide a combustion-supporting gas to the turbine engine; the air intake unit is located at the top of the muffling compartment, the muffling compartment comprises an accommodation space, the turbine engine and the starter are located in the accommodation space, and the starter is configured to start the turbine engine, the starter comprises a first electric motor.

A heat exchanger includes a heat exchanger body arranged along an axis and having an external surface in contact with a surrounding first fluid. The body defines a first fluid passage centered on and extending along the axis. The body also defines a second fluid passage extending parallel with respect to the axis and spaced away from the axis by a second passage distance, and a third fluid passage extending parallel with respect to the axis and spaced away from the axis by a third passage distance. The first, second, and third passages are parallel to one another, while the third passage distance is greater than the second passage distance. Each of the first and third passages is configured to accept a flow of a second fluid and the second fluid passage is configured to hold a volume of air to thermally insulate the first passage from the third passage.

A lubrication structure of the present invention is applied to a multi-link piston crank mechanism that has a upper link (3), a lower link (6) and a control link (7). Lubricating oil is supplied in an oil storing portion (21) formed between a pair of upper-pin pin boss portions (12) by a plate member (22) through an oil supply hole (19). By oscillating rotary motion of the upper link side pin boss portion (25) that is provided with an oil groove (29) on an end surface of the upper link side pin boss portion (25), the lubricating oil in the oil storing portion (21) is supplied to an upper pin (4).

A lubrication structure of the present invention is applied to a multi-link piston crank mechanism that has a upper link (3), a lower link (6) and a control link (7). Lubricating oil is supplied in an oil storing portion (21) formed between a pair of upper-pin pin boss portions (12) by a plate member (22) through an oil supply hole (19). By oscillating rotary motion of the upper link side pin boss portion (25) that is provided with an oil groove (29) on an end surface of the upper link side pin boss portion (25), the lubricating oil in the oil storing portion (21) is supplied to an upper pin (4).