129 results about "Viscous resistance" patented technology

The invention relates to the technical field of high-pressure dredge pump simulation calculation, and discloses a construction and application method of a high-pressure efficient dredge pump simulation calculation model. A model is established based on dynamic fluid-solid coupling parameters (mud pulsating pressure, impeller dynamic stress and the like), soil multiphase rheological parameters (particle phase volume fraction, viscous resistance coefficient and the like) and pipeline transient resistance parameters (transient pressure drop gradient and the like), and factors such as rotating speed-power matching and the like are incorporated to calculate an operation envelope and a critical failure threshold. A multi-physics field coupling analysis system comprising parameter configuration, dynamic simulation (integrating a flow field and a structural vibration solver) and a safety evaluation module is developed, after actually measured data and self-defined parameters are input, dynamic flow velocity distribution, pressure pulsation characteristics and the like are obtained through fluid-solid bidirectional coupling calculation, and an optimal configuration scheme is generated. The system supports database management, multi-rheological model matching and three-dimensional visualization, the simulation precision and the engineering efficiency are improved, and support is provided for performance optimization and safety evaluation of the high-pressure working condition.

The invention discloses a hydraulic oil cylinder with high buffering performance, and relates to the technical field of hydraulic oil cylinders, the hydraulic oil cylinder comprises a reciprocating motion assembly, and the reciprocating motion assembly is used for driving a piston rod to do reciprocating rectilinear motion. During use, when a sealing piston is about to move to a stroke terminal, a buffer ring generates thrust on an annular plate, so that two nitrile rubber pads are sunken, meanwhile, a reset spring is extruded and contracted, and under the cooperation of the reset spring and the nitrile rubber pads, the sealing piston is preliminarily buffered, and in addition, a connecting rod pushes a buffer plate to move in an arc-shaped cover; the piston rod body is filled with hydraulic oil and gradually extrudes polyurethane foam, the polyurethane foam has good buffering performance, the filled hydraulic oil generates viscous resistance, the extruded hydraulic oil can enter the buffering cavity through the oil inlet cavity, secondary buffering is conducted on the sealing piston under the cooperation of the polyurethane foam and the filled hydraulic oil, the movement speed of the piston rod body is gradually reduced, and the sealing effect is improved. And stable speed reduction and stopping are realized.

The invention discloses a viscous damping wall design method, device, equipment, medium and product, and the method comprises the steps: constructing a double-node model of a viscous damping wall and a first finite element model of a building frame structure, the double-node model takes a beam structure as nodes, and each node comprises at least one degree of freedom; the building frame structure at least comprises two beam structures; analyzing the double-node model to determine a damping coefficient analytic expression and a rigidity coefficient analytic expression; and arranging the double-node model in the first finite element model according to the damping coefficient analytic expression and the rigidity coefficient to obtain a second finite element model, and determining performance parameters of the viscous damping wall based on the second finite element model. According to the method, the influence of the damping coefficient on the viscous resistance is considered, and the influence of the rigidity coefficient on the viscous resistance is also considered, so that the finally obtained performance parameters of the viscous damping wall are more accurate and effective.

The invention discloses a resistance coefficient calculation method and device of a porous medium, the medium and equipment. The method comprises the steps that a three-dimensional geometric model of target equipment is constructed, a simulation area of the porous medium in the three-dimensional geometric model is determined, a simulation experiment is conducted on the target equipment, and an inlet and outlet experiment pressure difference is obtained; constructing an optimization model based on an inlet and outlet experiment pressure difference and an inlet and outlet simulation pressure difference, wherein the inlet and outlet simulation pressure difference is obtained by performing fluid simulation calculation on a three-dimensional geometric model based on a CFD control equation, a continuity equation, a CFD momentum conservation equation, a viscous resistance coefficient and an inertial resistance coefficient of a simulation area; taking the optimization model as a target function in a population algorithm, wherein position variables corresponding to individuals in the population algorithm are a multidirectional viscous resistance coefficient and a multidirectional inertial resistance coefficient; and solving the optimization model based on a population algorithm to obtain an optimal viscous resistance coefficient and an optimal inertial resistance coefficient. The identification accuracy of the inertial resistance coefficient and the viscous resistance coefficient is improved.

To precisely estimate the rolling viscosity resistance of an actual bearing.SOLUTION: A rolling bearing 1 includes trace surfaces 11a and 12a and a rolling body 13 for rolling on the trace surfaces. The rolling bearing 1 includes: a contact part in which the trace surfaces and the rolling body are in point-contact with each other, an oil film is formed in the point-contact part, and the trace surfaces 11a and 12a are in contact with the rolling body 13; and a contactless part as a part which is not in contact with the rolling body. The estimated value Fr,w of the rolling viscosity resistance is calculated from a regression equation on the condition that the calculation range of a contact ellipse in the direction of a longer axis is a length selected in the range from larger than a longer axis radius of a contact ellipse and to the equivalent radius in the axial direction.SELECTED DRAWING: Figure 2

The invention relates to the technical field of steel wire rope detection, and discloses an elevator steel wire rope tensile strength detection device and method.The elevator steel wire rope tensile strength detection device comprises a machine base, a detection frame arranged on the machine base, a control case and a lifting assembly arranged on the detection frame; the lifting assembly comprises a lifting seat, and clamping assemblies for clamping and fixing the steel wire rope are arranged on the upper side of the lifting seat and the detection frame. According to the elevator steel wire rope tensile strength detection device, through the cooperation between the protection assembly and the buffer assembly, damping liquid in the buffer part is extruded by the buffer plate and flows through the through holes, the viscous resistance of the damping liquid is used for attenuating the kinetic energy of a moving machine, and the effect of buffering force unloading is achieved; the flow rate of the damping liquid can be further slowed down through the retention hole in the through hole, the buffering and damping effect is enhanced, the counter-acting force generated when the steel wire rope is broken can be effectively attenuated through the arrangement, and the mechanical structure of the detection equipment is protected against damage.

The present invention discloses a hydraulic cylinder with high buffering performance, which relates to the technical field of hydraulic cylinders and includes a reciprocating moving component, wherein the reciprocating moving component is used to drive the piston rod to move back and forth linearly. When the present invention is used, when the sealing piston is about to move to the end of the stroke, the buffer ring generates a thrust on the annular plate, causing the two nitrile rubber pads to be concave, and at the same time the return spring is squeezed and contracted. With the cooperation of the return spring and the nitrile rubber pad, the sealing piston is initially buffered. In addition, the connecting rod pushes the buffer plate to move inside the arc cover and gradually squeezes the polyurethane foam. The polyurethane foam has good buffering performance. The filled hydraulic oil generates viscous resistance. The squeezed hydraulic oil will enter the buffer chamber through the oil inlet chamber. With the cooperation of the polyurethane foam and the filled hydraulic oil, the sealing piston is buffered for the second time, so that the movement speed of the piston rod body is gradually reduced, and smooth deceleration and stopping are achieved.

The invention discloses a rare earth-containing additive, which comprises rare earth metal and iron, wherein the content of the rare earth metal is 5wt% to 90wt%, and the content of the iron is 10wt% to 95wt%; the density of the additive is 6.3g / cm 3 ~8.4g / cm 3 , melting point is 850℃~1450℃, oxygen content is ≤150ppm, maximum size of inclusions is ≤35μm, total inclusions are ≤0.5wt%. By adjusting the density, melting point and shape of additives containing rare earth and iron, the applicable composition window of additives is increased, the speed of additives added to molten steel through the upper slag layer is increased, the viscous resistance of molten steel to additives is effectively reduced, the influence of slag layer is eliminated, the depth of rare earth additives is increased, and the depth of additives is effectively increased, thereby improving the rare earth yield and distribution uniformity.

The application discloses a stroke trigger type welding device and method, belongs to the field of high-speed wire welding, and comprises a support, a mounting plate slidably connected to one side of the support, a welding part fixedly connected to one side of the mounting plate, a motor fixedly connected to one side of the support, a restraint groove is formed in the mounting plate, a rotating disc is rotatably connected to one side of the support, a seat body is fixedly connected to one side of the rotating disc, a roller is rotatably connected to one side of the seat body, the roller is located in the restraint groove, a base is also fixedly connected to one side of the mounting plate and extends into the restraint groove, and an output shaft of the motor is connected with the rotating disc; the material scraping seat on the seat body can scrape off the paste on the outer surface of the rotating roller, after scraping, the frictional resistance is restored from nonlinear and sudden viscous resistance to linear and stable sliding or rolling friction, the single-stroke lifting movement of the mounting plate is more stable, and the crawling phenomenon of jamming is avoided.

The purpose of the invention is both to suppress viscous resistance loss at compressor start (normal temperature) and improve oil film load performance during operation (high temperature) in a refrigerating machine oil and a refrigerating device. A refrigerating machine oil according to the present disclosure is for a refrigerating device in which propane is sealed therein as a refrigerant, said refrigerating machine oil containing an ester-based oil having a viscosity grade of ISO VG32 or less, and a viscosity index improver containing a polymethacrylic acid ester having a C1-18 alkyl substituent, the concentration of the polymethacrylic acid ester being from 0.6 to 6 wt%.

The crankshaft and the compressor comprise a short shaft, a long shaft and an eccentric part, the eccentric part is arranged between the long shaft and the short shaft, a first oil outlet hole is formed between the eccentric part and the long shaft, and a second oil outlet hole is formed between the eccentric part and the short shaft; a groove is formed in the end, close to the first oil outlet hole, of the circumferential face of the long shaft, and / or a groove is formed in the end, close to the second oil outlet hole, of the circumferential face of the short shaft. According to the arrangement, the lubrication degree of the eccentric part of the crankshaft is improved through the slotting design, and the viscous resistance of an oil film is effectively reduced.

The invention relates to the field of titration experiments, in particular to an air pressure driven anti-blocking viscous aid titration device and method. The pneumatic-driven anti-blocking viscous aid titration device comprises a burette, a sealing cover and the like, and the burette is screwed with a sealing cover through threads. Through inert gas constant-pressure driving, viscous resistance is overcome, pipe wall adhesion is inhibited through gas pressure, the problem of blockage is avoided during continuous titration of an auxiliary agent, and compared with traditional gravity titration, the flow velocity fluctuation rate of the auxiliary agent is greatly reduced, so that the experiment batch difference is effectively reduced, and the experiment efficiency is improved. It is guaranteed that the auxiliaries stably flow out in the state of filling the outflow channel all the time under the condition of any discharging opening, and the problems that under the condition that an existing valve is small in opening, the auxiliaries flowing out by means of gravity cannot flow out in the state of filling the outflow channel, and then part of the auxiliaries adhere to the inner wall of the channel in the outflow process and cannot flow out in time are solved. And the flow rate fluctuation rate of the auxiliary agent is large.

The invention provides a flow and boiling heat exchange rapid analysis method and device based on a porous medium, and relates to the technical field of porous medium heat transfer characteristic measurement, and the method comprises the steps: obtaining initial experiment data through an experiment device, and the initial experiment data comprises on-way pressure drop, wall surface temperature data and inlet and outlet temperature data of the porous medium; the fluid velocity and the fluid viscosity of the fluid in the porous medium are measured; based on the on-way pressure drop, the fluid flow velocity and the fluid viscosity, the resistance coefficient of the porous medium is obtained through calculation, and the resistance coefficient comprises an inertia resistance coefficient and a viscous resistance coefficient; calculating an equivalent heat conductivity coefficient of the porous medium according to the wall surface temperature data and the inlet and outlet temperature data; on the basis of a reduced-order one-dimensional N-S equation, a flow and heat exchange analysis model is built in combination with the physical property of the water vapor surface; and substituting the resistance coefficient and the equivalent heat conductivity coefficient into a flow and heat exchange analysis model, and predicting flow characteristics and heat exchange characteristics of the porous medium under different flow and pressure conditions. The flow and heat exchange characteristics of the porous medium material can be rapidly analyzed.

The utility model relates to the technical field of anti-vibration, and discloses a high-damping anti-vibration seat of integrated circuit equipment, which comprises an anti-vibration seat and a base. According to the high-damping anti-vibration seat of the integrated circuit equipment, through the arrangement of the supporting seat, the base, the damping mechanism and the elastic mechanism, when the integrated circuit equipment is vibrated, the acting force borne by the supporting seat can be transmitted to the piston rod, the piston rod is forced to vibrate, and magnetorheological fluid is pushed to flow in the annular cavity; a magnetic field generated by the permanent magnet array enables magnetorheological fluid particles to form a chain-shaped structure, fluid shear stress is greatly increased, nonlinear viscous resistance is generated, meanwhile, vertical reciprocating motion of the piston rod cuts magnetic induction lines of the permanent magnet array, an eddy current effect is triggered, reverse electromagnetic damping force is generated, and the damping effect is improved. Therefore, magnetic circuit cutting and fluid extrusion are achieved while movement of the piston rod is achieved, a composite energy dissipation mechanism of electromagnetic damping and viscous damping is formed, and the energy dissipation efficiency and the resonance peak suppression efficiency are remarkably improved.

This invention belongs to the field of vibration control technology and discloses a viscous damper for controlling vertical vibration. The viscous damper adopts a double-cylinder, unsealed structure. The two cylinders are connected by a connecting rod hole in the middle of the cylinder partition. One end of the connecting rod is rigidly connected to a piston inside the second cylinder, and the other end passes through the cylinder partition and the top plate of the first cylinder before connecting to a structure. The bottom of the second cylinder is connected to another structure. When the two structures generate a vertical relative velocity, the connecting rod drives the piston to move in the damping fluid of the second cylinder, generating viscous resistance and suppressing the relative motion of the two structures. This invention does not require strict sealing, has a simple structure, low manufacturing cost, and better durability. The damping coefficient can be dynamically adjusted as needed by the comb teeth or the gradually changing inner cavity of the cylinder, resulting in higher efficiency compared to traditional dampers. This invention can effectively control the vertical or slightly inclined relative motion between various large structures such as bridges, cables, building internal structures, and marine engineering projects caused by various dynamic loads.

The invention discloses a rapid numerical prediction method for flow resistance of a shellfish trap, and relates to the field of flow resistance analysis of a nuclear power seawater cooling system. A filter screen explicit modeling or experimental testing mode is mostly adopted for flow resistance analysis of an existing shellfish catcher, and the problems that the calculation scale is large, the simulation period is long, the cost is high, or parameters depend on experience, and the engineering applicability is insufficient exist. On the basis of a porous medium equivalent modeling thought, on the premise that the porosity of the filter screen is kept consistent, a filter screen area is replaced with a porous medium area, only the viscous resistance effect in direct proportion to the flow velocity is introduced, and through pressure drop comparison of an explicit filter screen model and a porous medium model, iterative fitting is conducted on viscous resistance parameters, so that the filter screen porosity is calculated. And fitting parameters are applied to the integral model of the shellfish trap, so that rapid numerical calculation of the flow resistance characteristic is realized. The method is suitable for engineering design, operation analysis and flow resistance rapid evaluation of shellfish traps and similar high-porosity filtering structures in a seawater cooling system of a nuclear power station.

The utility model discloses a mine mining crushing device, which relates to the technical field of ore crushing devices and comprises a shell, four mounting holes are formed in the outer surface of the shell, supporting blocks are embedded in the four mounting holes, every two supporting blocks form a group, and the opposite surfaces of the two groups of supporting blocks are rotationally connected with crushing rollers through bearings. According to the utility model, when the instantaneous impact force is too high, the two crushing rollers transmit kinetic energy and extrude the four buffer pieces through the two supporting blocks, the four dampers compress the stroke after being stressed, the amplitude is attenuated, the vibration is inhibited and the buffer is provided through viscous resistance, and meanwhile, the four springs compress the stroke and absorb the kinetic energy, so that the situation that the crushing rollers are damaged during mining and transportation is effectively avoided; and the instant impact force borne by the crushing rollers when the ores are extruded is too high, so that the service life of parts is guaranteed.

The present invention relates to the technical field of heat exchangers, and specifically relates to a method for overall three-dimensional numerical simulation of an intercooler under a local non-thermal equilibrium state. S1: Extract a periodic repeating micro-element structure of the intercooler as the object of simulation research. S2: Under the given inlet and outlet conditions, calculate the heat transfer quantity q of the micro-element structure r , the viscous resistance coefficient D of the hot-side fins h and the inertial resistance coefficient C h , the viscous resistance coefficient D of the cold-side fins c and the inertial resistance coefficient C c . S3: Establish a periodic micro-element model with the hot-side fins removed, and solve for the equivalent porosity ε of the hot-side channel e,h ; S4: Establish a periodic micro-element model with the cold-side fins removed, substitute it with the local thermal equilibrium model of porous media, and solve for the equivalent porosity ε of the cold-side channel e,c ; S5: Establish an overall three-dimensional simplified model, and solve for the pressure loss and heat transfer quantity of the entire heat exchanger under the specified inlet and outlet conditions. The simulation method proposed by the present invention can accurately simulate the performance of complex heat exchangers under a non-thermal equilibrium state.

The invention discloses a multi-branch pipe flow uniformity optimization method based on valve equivalent resistance model mapping, which comprises the following steps of: 1, replacing a real valve with an equivalent resistance area, performing CFD (Computational Fluid Dynamics) simulation on a single valve and a single pipe, and establishing a mapping table of the opening degree, the viscous resistance of the equivalent resistance area and the inertial resistance; 2, establishing a multi-branch-pipe CFD model, querying a mapping table for the opening degrees of all valves, randomly generating an inertia resistance coefficient and a viscous resistance coefficient, constructing a dual-objective optimization function by taking the virtual opening degree of each branch pipe as a design variable, then calling CFD to solve all the branch pipes, and returning the dual-objective optimization function, so as to obtain a multi-branch-pipe CFD model; the flow unevenness of each branch pipe and the most unfavorable loop resistance in the system are output, multi-objective optimization and global optimization are carried out by adopting an NSGA-II algorithm, and a Pareto leading solution set of an optimal valve opening combination is output for a user; and 3, the flow of the multiple branch pipes is leveled through the optimal valve opening degree combination. The method has the advantages of modeling simplification, high calculation efficiency, short optimization period, strong adaptability and good stability.

The present invention provides a crankshaft and a rotary compressor, wherein the crankshaft includes an eccentric portion protruding in the radial direction and eccentrically arranged with respect to its own central axis; the eccentric portion has an oil groove and a groove recessed inwardly in the outer wall along its own radial direction; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove is used to extend from the oil groove and along the predetermined rotation direction. The present invention can reduce the contact area between the eccentric portion and the piston by providing the groove as described above, and the groove extends from the oil groove and along the predetermined rotation direction, so that the groove corresponds to the direction of the gas resultant force during the intake stage and the beginning of compression of the rotary compressor, and the groove faces away from the direction of the gas resultant force when the rotary compressor completes gas compression and during the exhaust stage, so that the gap between the eccentric portion and the piston is large enough, thereby reducing the viscous resistance of the oil film and improving the performance of the rotary compressor.

A swim cap with improvements to the design of the exterior surfaces of the cap that result in a decrease in viscous drag while swimming. A swim cap that incorporates scale tiles arranged in an array format on the exterior surface of the swim cap. A swim cap with scale tiles arranged in an array configuration that follow a uniquely defined linear flow pattern. A swim cap with scale tiles arranged in an array configuration to a uniquely defined linear flow pattern that can be formed by molding. A swim cap with scale tiles arranged in an array configuration to a uniquely defined linear flow pattern that conforms to the geometry of the specific human head it is applied to without altering the head form shape.

The invention relates to the technical field of wind turbines, in particular to an airfoil resistance coefficient calculation method and system considering multi-stage vortexes, and the method comprises the steps: constructing a second-order motion equation used for solving a resistance item caused by dynamic shedding vortexes of an airfoil; calculating an induced resistance item considering the vortex induced velocity; calculating a viscosity resistance item considering the viscosity influence; and superposing the resistance item caused by the dynamic shedding vortex, the induced resistance item, the viscous resistance item and static resistance corresponding to an effective attack angle to obtain an airfoil resistance coefficient. According to the airfoil resistance coefficient calculation method, the influence of various factors on the airfoil resistance coefficient is considered when the dynamic stall model is established, so that the dynamic stall model is corrected, the calculation result of the model corrected by using the airfoil resistance coefficient calculation method is more consistent with the experimental result under the dynamic working condition, and the accuracy of the airfoil resistance coefficient calculation method is improved. And the calculation precision of the model for the resistance coefficient under the dynamic working condition is effectively improved.

The invention discloses a method for determining the resistance coefficient of a porous medium of a permeable building in CFD (computational fluid dynamics) numerical simulation, which comprises the following steps of: measuring upstream and downstream water depths and flow velocities of the permeable building under a given incoming flow condition by adopting a series of physical model tests, and acquiring hydraulic characteristics of the permeable building under different geometric scale conditions; the method comprises the following steps: inverting physical model tests with different scales through CFD numerical simulation, simulating a permeable building by adopting a porous medium in a CFD model, calculating the resistance of the porous medium to water flow by adopting a resistance formula in a Forchheimer form, and obtaining the resistance characteristic of the permeable building; establishing a mathematical relationship between the viscous resistance coefficient and the geometric scale and between the inertial resistance coefficient and the geometric scale, and determining the viscous resistance coefficient and the inertial resistance coefficient under the prototype scale and other unknown scales. According to the method, the accuracy of the resistance coefficient of the porous medium of the permeable building is improved, and the method is suitable for submerged and water outlet type permeable buildings composed of various porous or open structural bodies.

The application provides a large bulk carrier speed power prediction method and system, first, the trial data of a large bulk carrier and a ship model and the resistance data of the ship model measured in the test are obtained, and the main dimension parameter data of the ship model is obtained, then the CFD superposition method is used for calculation to establish a stable calculation strategy, then the StarCCM+ software is used for CFD simulation of the ship model according to the stable calculation strategy, the frictional resistance and the viscous pressure resistance of the ship model are obtained, the second frictional resistance coefficient of the ship model and the frictional resistance coefficient of the ship are calculated respectively by using the frictional resistance formula, and the first shape factor of the ship model is calculated, finally, the viscous resistance coefficient of the ship is calculated according to the frictional resistance coefficient of the ship and the first shape factor, the speed power of the ship is calculated according to the viscous resistance coefficient of the ship, the second frictional resistance coefficient of the ship model and the total resistance coefficient of the ship model in the test data, the prediction speed is effectively improved, the modeling cost is reduced, and the prediction precision is greatly improved.

The present application relates to a simulation method for simulating a liquid viscosity coefficient measurement experiment using a falling ball method based on Matlab GUI. The method, which is developed based on Matlab GUI, can truly simulate the experimental process of measuring the liquid viscosity coefficient using the falling ball method. The starting point exploration module for uniformly falling balls of different diameters can determine the starting time, starting position and starting speed (average speed in the uniform motion interval) of the ball entering a uniform falling state under the action system of three forces: gravity, viscous resistance and buoyancy. The simulation process is accurate, and students can intuitively see the entire dynamic demonstration process of the ball falling. At the same time, the temperature of the liquid and the diameter of the container in which the liquid is placed can be adjusted to explore the changing rules of the experimental results, deepen students' understanding of the experimental content, avoid errors caused by students' independent observation, and allow students to broaden their horizons and expand their knowledge.

The invention belongs to the field of ship viscous resistance evaluation, and particularly discloses a marine vehicle viscous pressure resistance acquisition method based on considerable ellipsoid hypothesis, which comprises the following steps: establishing a geometric model of a marine vehicle, gridding the geometric model, and determining centroid geometric coordinates, surface element area and surface element external normal vectors of a surface element grid; dividing a flow separation area of the geometric model according to a velocity vector of a remote unit incoming flow and a normal vector outside a surface element; calculating a projection perimeter, a projection area and a shape factor according to the flow separation area, constructing a considerable ellipsoid of the marine vehicle, and determining the geometric dimension of the considerable ellipsoid; the characteristic length of the marine vehicle is determined according to the geometric dimension, the Reynolds number of the marine vehicle is calculated, and the viscosity-pressure resistance coefficient of a considerable ellipsoid is obtained through an interpolation method; and acquiring the viscous pressure resistance of the marine vehicle according to the viscous pressure resistance coefficient, the fluid density, the incoming flow velocity and the wet projection area. According to the invention, the accuracy and efficiency of acquiring the viscous pressure resistance can be improved.

The crankshaft comprises a short shaft, a long shaft and an eccentric part, the eccentric part is arranged between the long shaft and the short shaft, a first oil outlet hole is formed between the eccentric part and the long shaft, and a second oil outlet hole is formed between the eccentric part and the short shaft; a groove is formed in the end, close to the first oil outlet hole, of the circumferential face of the long shaft, and / or a groove is formed in the end, close to the second oil outlet hole, of the circumferential face of the short shaft. According to the arrangement, the lubrication degree of the eccentric part of the crankshaft is improved through the slotting design, and the viscous resistance of an oil film is effectively reduced.

A rolling bearing (1) has raceway surfaces (11a, 12a) and rolling bodies (13) that roll on the raceway surfaces. In this rolling bearing (1), the raceway surfaces are in point contact with the rolling elements, an oil film is formed at the point contact portion, and the raceway surfaces (11a, 12a) have a contact portion that is in contact with the rolling elements (13) and a non-contact portion that is not in contact with the rolling elements. The calculation range in the long axis direction of the contact ellipse is set to a length selected within a range that exceeds the long axis radius of the contact ellipse and is equal to or less than the axial equivalent radius, and an estimated value (Fr, w) of the rolling viscous resistance is calculated from a regression equation.

The utility model belongs to the technical field of spray covers, and mainly relates to a spray cover and an aerosol can, the spray cover comprises a pressing block movably assembled on a can body, the pressing block is provided with an insertion pipe and a nozzle which are communicated with each other, and the outer side of the insertion pipe is sleeved with a slow release assembly; the slow release assembly comprises a piston and a cavity with a sealed cavity, the piston and the cavity are connected to the outer side of the insertion pipe in a sleeving mode, and the piston is fixedly connected with the pressing block through a sleeve connected to the insertion pipe in a sleeving mode. The cavity is used for being filled with liquid with viscous resistance, the piston divides the cavity into a first cavity and a second cavity which are communicated with each other, and the pressing block is moved to drive the piston to slide in the cavity so that the liquid can flow between the first cavity and the second cavity; the insertion pipe is sleeved with a spring, and the two ends of the spring are connected with the pressing block and the cavity respectively. The reset speed of the pressing block is delayed through the synergistic effect of the viscous resistance of the slow release assembly and the elastic force of the spring, and therefore the valve rod can still be kept in the open state temporarily after pressing is stopped, and continuous release of spray is achieved.

The utility model discloses a midwifery apparatus for assisting delivery in obstetrics, which relates to the technical field of medical instruments and comprises a damping outer cylinder, damping plate components are mounted and connected to two sides of the inside of the damping outer cylinder, and a damping inner cylinder is rotatably connected to the center of the two damping plate components. The two ends of the damping inner cylinder are slidably connected with elastic resistance assemblies. Damping fluid stored in the damping outer cylinder is used as a main resistance source when a puerpera is trained, when the damping fluid passes through the groove holes in the surface of the piston plate with the holes, the viscous resistance of damping passing through the groove holes and changing linearly is used as the main resistance source when the puerpera is trained, the puerpera can be effectively protected, and meanwhile the damping fluid is prevented from being damaged. When the reset springs push the piston plates with the holes to reset, due to the existence of viscous resistance, the distance between the two piston plates with the holes is low, and the problem that in the reset process of the piston plates with the holes, leg muscle groups of a puerpera are strained due to the fact that the reset speed is high is solved.