Abstract: A vacuum pump having a rotary shaft that is rotated by a drive source has a main pump and a sub pump. The main pump includes a pump chamber and a gas transferring body that is located in the pump chamber. The main pump is driven by the drive source through the rotary shaft for transferring gas to an exhaust space. The sub pump is connected to the exhaust space for partially exhausting the gas from the exhaust space. The sub pump is driven by the same drive source. The displacement volume of the sub pump is smaller than that of the main pump.

Abstract: A vacuum pump has an oil housing, which defines a pump chamber and an oil zone adjacent to the pump chamber. A rotary shaft extends from the pump chamber through the oil housing and projects to the oil zone. A stopper is attached to the rotary shaft to integrally rotate with the rotary shaft. The stopper prevents oil from entering the pump chamber. The vacuum pump draws gas by operating a gas conveying body in the pump chamber through rotation of the rotary shaft. When the rotary shaft shifts from an operation state to a stopped state, the pressure difference occurs between the pump chamber and the oil zone. Rotation of the rotary shaft is controlled such that the pressure difference becomes maximum before the rotary shaft completely stops.

Abstract: A Roots pump rotates a plurality of rotors by a pair of rotary shafts to draw gas. Each rotary shaft extends through a rear housing member of the Roots pump. A plurality of stoppers are located on each rotary shaft to integrally rotate with the corresponding rotary shaft, and prevent oil from entering a fifth pump chamber of the Roots pump. Stoppers have a circumferential surface, respectively. Annular oil chambers collect oil. The oil chambers are located about an axis of the rotary shaft to surround the circumferential surface of the stopper. This effectively prevents oil from entering the pump chamber of the Roots pump.

Abstract: A ring-shaped sealing member comprises a ring-shaped base material having elastic properties, and a barrier film formed on a surface of the base material. The barrier film is comprised of a resin material which is less permeable to gas than a butyl rubber. Another ring-shaped sealing member of the present invention comprises, only at part of the circumferential direction thereof, a stretching portion which is stretchable in the circumferential direction. Therefore, the operation efficiency in the fitting is improved, and a leakage of a gas can be satisfactorily prevented. In addition, the sealing member has a simple structure, and thus is able to downsize a housing to which the sealing member is fitted. Further, permeation of CO2 gas can be satisfactorily controlled.

Abstract: A first housing member and a second housing members are coupled to each other. A recess is formed in the second housing member to face the first housing member. An O-ring is accommodated in the recess. A block ring is located in the recess and extends along the O-ring. The block ring is closer to an unsealed space than the O-ring and is made of a high gas permeation resistance material. Therefore, even if the pressurized gas in a sealed space permeates the O-ring, the block ring prevents the gas from leaking to the unsealed space.

Abstract: An improved housing seal. Resin is applied to the outer surface of a joint between adjacent housing members. This produces an effective, simple in structure, and inexpensive seal that limits the size of the housing.

Abstract: A compressor includes a cylinder block and a housing connected to the ends of the cylinder block. A suction chamber and a discharge chamber are defined in the housing, respectively, and the chambers are divided by a bulkhead, or wall. A valve plate, which has a discharge port for connecting the cylinder bores with the discharge chamber, is positioned between the cylinder block and the housing. A discharge valve is provided for selectively opening and closing the discharge port. A gasket is positioned between the housing and the valve plate, and the gasket is held to the bulkhead. The gasket has a bulkhead seal portion, which is between the bulkhead and the valve plate for sealing between the discharge chamber and the suction chamber, and a protruding portion, which protrudes radially beyond the bulkhead, extending along and contacting the valve plate.

Abstract: A refrigerant compressor, for compressing a refrigerant gas and delivering the compressed refrigerant gas toward an external refrigerating system, which has at least a rear housing provided with a rear discharge chamber defined by a partition wall and a rear discharge valve assembly including a rear discharge valve element and a rear retainer element coated with a rubber material, the partition wall having an endmost first end surface holding a base portion of the rear discharge valve element and a base end portion of the rear retainer element, a tapered surface portion extending toward a rear direction from the endmost first end surface, and a second end surface extending from the rear end of the tapered side surface to be parallel with the first end surface, the tapered surface portion and the second end surface defining a cavity and a support portion to prevent an uncontrolled deformation of controlling portions of the retainer element which control an amount of opening of the valve portions of the rear di

Abstract: The retainers of a reciprocating compressor are kept from deforming by the pressure of discharged refrigerant when there is a overload due to liquid compression and so forth, by linking inclined pieces with a gentle slope on the retainers serving as members for restricting the opening angle of the reed valve type discharge valves, with a linking member or by making the width dimension of the base portion of the inclined pieces with a gentle slope greater than the width dimension of the tip portion thereof, thereby improving the rigidity of the retainers, and consequently improving the reliability of the reciprocating compressor.

Abstract: An improvement of a piston type compressor is disclosed. The compressor has a cylinder block that includes a plurality of cylinder bores and a plurality of suction passages. Each of the suction passages extends through the cylinder block to connect a crank chamber with a suction chamber. The suction chamber is connected with the cylinder bores via a plurality of suction ports located in association with the cylinder bores. Each cylinder bore accommodating a piston that moves therein to circulate gas between the compressor and an external gas circuit. The gas introduced into the crank chamber from the external gas circuit is supplied to the suction chamber through each suction passage and is supplied from the suction chamber to each cylinder bore through an associated suction port. The suction passages are smaller in number than the cylinder bores. The suction ports are disposed in the vicinity of an opening of the suction passages.

Abstract: A coil box apparatus provided between a roughing roll and a finishing mill at a hot rolling mill so as to coil a rolled material transported from the roughing mill in order to make the temperature distribution of the rolled material more uniform, which is provided with a controller for computing a stand-by time of the coiled rolled material in a coil box on the basis of a condition of proceeding a rolling operation of an advanced rolled material at the finishing mill of the downstream side process, and predicting a temperature difference between the outermost first coiled layer and the inside coiled layers from the second coiled layer of the coiled rolled material after the lapse of the computed stand-by time with reference to information of the previously stored temperature drop at each part of the coiled rolled material, so that when the predicted value is larger than the reference value, the coiled rolled material is covered on the surface of the outermost first coiled layer thereof by coil covers formed o

Abstract: A diagnostic apparatus which diagnoses a failure of the machine by comparing a relation between the displacement amount of a varible for making the variable coincide with a target value while the machine is normally operated and the response time required thereof with that while the machine is actually operated. Accordingly the apparatus can diagnose the failure based on transient response while the machine is actually operated, so that early detection of the failure is possible without additional measures.

Abstract: In a method of trimming a width of an elongate sheet stock by a side trimmer, respective minimum widths of both side portions, i.e. a work side portion and a drive side portion, of the stock are measured in advance, and then respective trimming allowance values of the two side portions are determined on the basis of the thus measured minimum widths thereof, respectively. According to this method, the elongate stock can be kept free from insufficiency of the trimming allowance during the trimming operation. Thus the present method makes it possible to determine an optimum set value for the side trimmer to trim the elongate stock in consideration of the actual width of the stock and a desired final width of a finished stock or product.

Abstract: A method for realizing energy saving, for each of a plurality of mills provided in the hot rolling line, during the pause period until a successive work piece arrives a mill from a preceding work piece separates from a mill. The pause period is forecasted on the basis of a supply interval of work pieces supplied to the rolling line and a period of stay of work piece at each mill, and the mill is set in the pause state within the period defined by subtracting the preparation period required by the mill to reach the steady state from start of operation from such foreseen pause period.

Abstract: A method of controlling an edging opening in a rolling mill, comprising measuring a width distribution of a plate to be rolled at an inlet of an edging roll in the rolling mill, calculating beforehand a width deviation distribution and a length in the moving direction of the plate at an irregular deformation portion caused in a rolling process in accordance with a predetermined pass schedule and a target width deviation distribution of the rolled plate required at an outlet of the rolling mill, calculating an optimum edging opening variation distribution using a plate width adjustment efficiency calculated on the basis of the beforehand calculated value and supplying the optimum edging opening variation distribution to an edging opening setting unit for the feedforward control.