Abstract: An oil-free two-stage vacuum pump includes first and second pump stages coupled in series. The first and second pump stages have discharge spaces capable of communicating with each other via a bypass passage. The bypass passage is provided with a pressure control valve which is closed when pressure in the bypass passage is lower than a predetermined pressure. This permits a reduction in scroll size. In addition, the pump is free from problems present in pumps with large scroll sizes such as drive shaft vibrations due to warping thereof at high speed rotation, noise and heat generation, and durability reduction due to causes such as non-uniform contact between stationary and revolving scrolls. Moreover, in a compression step in the first pump stage, withdrawn gas is under high pressure; the gas pressure in a sealed vessel is close to the atmospheric pressure in an initial stage of driving.

Abstract: The present invention is intended to provide an oilless scroll-type compressor which can obtain a high compression efficiency with highly accurate sealability retained and particularly has such a constitution that a chip seal fitted in each of the wrap end surfaces of stationary scrolls and an orbiting scroll is integrated with a backup seal, a discharge port in communication with a wrap groove terminal end through a through-hole is formed in a land section positioned on the interior side of a wrap inner circumferential end on the side of one scroll and situated around a shaft hole through which a main shaft is inserted, and the circumference of said discharge port is surrounded by the chip seal extended from said wrap.

Abstract: An air spray gun comprising a nozzle with a frustoconically profiled tip, a cylindrical through bore, a V-shaped groove running across said through bore to form an oblong opening for ejecting paint under a pressure of 1 to 6Ckgf/cm.sup.2 and atomizing the ejected paint by compressed air having a pressure of 0.5 to 2 kgf/cm.sup.2, wherein an air cap is arranged to form an annular air outlet between the outer periphery of the nozzle tip and a central air outlet of the air cap and the nozzle tip is located within a front central through bore of the air cap.

Abstract: A premixing-type spray gun which mixes a paint and compressed air inside the atomizing head thereof and sprays out the mixture as atomized from the spray hole, having a flow control valve to adjust the sectional area of the paint supply path communicating with the paint nozzle or having a relief valve disposed downstream of a throttle path made of the inlet path through which the spraying air pressure is partially supplied into the pressurizing container.The flow rate of the paint can be adjusted independently of the trigger operation of the spray gun, and the amount of the paint suppled under pressure can be controlled, thereby keeping a stable spray amount.

Abstract: The present invention is a premixing-type spray gun which mixes a paint and compressed air inside the atomizing head and blows out the mixture as atomized from the spray hole. The inner and outer surfaces of the center hole in the atomizing head of the spray gun body are conical, and there is formed at the center of the cap having a nearly concentrical thickness at a lip-like aperture by providing a generally V-shaped recess from outside. Paint can be sprayed under a pressue of less than 1 kgf/cm.sup.2 with which the paint is less scattered, and the sprayed particle sizes can be made fine as with the conventional air spray guns.

Abstract: A low pressure atomizing spray gun is disclosed in which paint is injected from a nozzle, an opening of the nozzle is controlled by a needle valve, air is mixed with a flow of paint, air is blown from both sides after the air-paint mixture is sprayed from a spraying nozzle and it is again mixed and atomized. The nozzle is formed as circular hole with a circular outer shape, and the spray hole is designed with a lip-like shape having different dimensions in longitudinal and lateral directions and with a conical or similar shape. Lateral air holes are furnished in front of the spray hole, at opposite positions on both sides of the spray flow and function to blow the diffusing air flow toward the spray flow. A pair of longitudinal air holes is furnished to inject the secondary air obliquely from behind the spray hole and to make the air collide with the flattened spray pattern.

Abstract: The present invention relates to an oilless reciprocating compressor and expansion apparatus each comprising a piston body to which a piston ring made of a self-lubricating material is fitted and a metal cylinder, and in the first invention and the second invention a self-lubricating material can be formed on the piston itself or on the circumferential surface side thereof without influencing adversely the durability of the piston itself by the compression heat at the piston top, and in the third invention a ring groove formed into the shape of the letter C whose ends are spaced a little is provided in the piston circumferential surface at least whose surface side is made of a self-lubricating material, and said ring groove is positioned on the side thrust line orthogonal to the piston pin, so that the compression efficiency is improved.

Abstract: A spraying method wherein the distance between a spray apparatus and an article is measured by a distance measuring means provided on the spray apparatus, and a spraying condition in which a substance is sprayed is varied in accordance with the measured distance. Also disclosed is a spray apparatus which is suitable for carrying out the above-described method. The apparatus has a supply passage for a substance which is to be sprayed, a nozzle for jetting out the spray substance, and a control valve means provided within the supply passage and adapted to control the flow rate of the spray substance flowing out through the nozzle. A distance measuring means is provided integral with the spray apparatus in one unit, the means being adapted to measure the distance between the spray apparatus and an article and output a signal corresponding to the measured distance. The degree of opening of the control valve means is determined on the basis of the signal output from the distance measuring means.

Abstract: A spray gun with an automatic valve opening control means which enables remote and stepless control of a paint spraying operation has atomizing means provided at the front end thereof, a paint valve member which enables adjustment of the amount of paint jetted out from the atomizing means, and a spray pattern adjusting valve member adapted to adjust the spray pattern by controlling the amount of compressed air jetted out from the atomizing means. A threaded slider mechanism is provided on the proximal portion of a valve body of either the paint valve member or the spray pattern adjusting valve member (or both). A servo motor and an encoder are connected to a drive screw member of the threaded slider mechanism. The encoder is adapted to detect the rotational position of the servo motor and output a controlled variable of the motor, and the servo motor is controlled in response to an external signal.

Abstract: An automatic spraying method wherein the amount of displacement of a valve member is calculated from data representing a particular spray distance by means of a microcomputer, and the valve member is activated on the basis of the displacement amount thus obtained. A curve which represents the relationship between the valve member displacement and the amount of a fluid which is to be jetted out is experimentally obtained in advance, and this curve is approximated by a plurality of straight lines or parabolas. The slopes or average slopes of these lines or curves are obtained, and the ratio between the respective slopes of the sections which are adjacent to each other is calculated. Trial spraying is carried out at two different spray distances within a range of valve member displacement amounts so as to provide a desired coating, and the relationship between the spray distance and the valve member displacement amount which provides similar coatings is obtained at two points.

Abstract: A shaft sealing device is disposed on the sliding portion of a needle valve stem in a spray gun for spraying a compressed fluid (paints), particularly in an airless paint spray gun, and is capable of enhancing the durability of the portion to be sealed. The shaft sealing device comprises a main packing for the needle valve which permits the needle valve stem to be pierced therethrough and slid in the center thereof. The shaft sealing device has a concave portion formed therein in the axial direction, a ring-shaped auxiliary packing of an elastic rubber body fitted in the concave portion, a packing rest provided with a convex portion, and a packing gland for tightening the main packing from behind. The packing gland tightens the ring-shaped auxiliary packing which is elastically deformed. The elastic deformation of the auxiliary packing extends to the main packing, whereby the needle valve stem can be uniformly sealed with the main packing and stable durability can be obtained even by a small tightening force.

Abstract: A pressure coating roller gun has a spray nozzle having a spray opening formed in front of the central jet orifice, the opening having a bevel impingement wall. By the use of this nozzle, a coating material is sprayed in the form of a divergent thin film over the coating roller surface. The coating roller preferably has a length corresponding to the width of the divergent thin film of coating material sprayed from the spray nozzle. A spherical coupling member is provided at the proximal end of the spray nozzle so as to allow free adjustment of the direction of spray.