1003 results about "Axial distance" patented technology

The invention provides a same-side input double-shaft compressor tester rotor concentricity reserving method, which belongs to aero-engine tests and comprises the following steps: determining thermal expansion displacement of an exhaust passage and a gear box support structure in a same-side input double-shaft compressor tester, according to the thermal expansion displacement and the axial distance, the thermal expansion displacement of the input flange of the biaxial compressor test piece and the thermal expansion displacement of the output flange of the gearbox are obtained through calculation, and then the estimated cold and hot state concentricity variation is obtained; according to the estimated cold and hot state concentricity variable quantity, the estimated cold state concentricity is calculated by taking the hot state concentricity as zero, and the rotor of the double-shaft compressor tester is arranged according to the estimated cold state concentricity; vibration measuring points and bearing temperature measuring points are arranged for testing, the operation state of the double-shaft compressor tester is judged through the vibration measuring points and the bearing temperature measuring points, and if the operation state meets the requirement, the estimated cold-state concentricity meets the requirement; and if the operation state does not meet the requirement, the estimated cold state concentricity is corrected.

A photographing optical lens assembly comprising six lens elements (E1, E2, E3, E4, E5 and E6), wherein the six lens elements (E1, E2, E3, E4, E5 and E6) are, in order from an object side to an image side along an optical path, a first lens element (E1), a second lens element (E2), a third lens element (E3), a fourth lens element (E4), a fifth lens element (E5) and a sixth lens element (E6), and each of the six lens elements (E1, E2, E3, E4, E5 and E6) has an object-side surface facing the object side and an image-side surface facing the image side; wherein the first lens element (E1) has a negative refractive power, the object-side surface of the second lens element (E2) is concave in a paraxial region thereof, and the image-side surface of the third lens element (E3) is concave in a paraxial region thereof; and wherein an axial distance between the object-side surface of the first lens element (E1) and the image-side surface of the sixth lens element (E6) is TD, a focal length of the photographing optical lens assembly is f, a focal length of the fifth lens element (E5) is f5, an axial distance between the fifth lens element (E5) and the sixth lens element (E6) is T56, an axial distance between the object-side surface of the first lens element (E1) and an image surface (IMG) is TL, a maximum image height of the photographing optical lens assembly is ImgH, and the following conditions are met: 2.20 < TD / f < 4.50 ; − 0.80 < f / f5 < 0.20 ; 1.00 < TD / T56 < 35.00 ; and 0.50 < TL / ImgH < 4.00.

The invention relates to an atrial septum puncture system, and belongs to the technical field of medical instruments. The atrial septum puncture system comprises a conveying sheath assembly, a dilator assembly and a puncture guide wire. The dilator assembly comprises a dilator, a puncture needle and a control handle. The conveying sheath assembly, the dilator assembly and the puncture guide wire are combined into the atrial septum puncture system, puncture operation is more convenient and safer, and the puncture guide wire and a puncture needle do not need to be frequently exchanged in the puncture operation process; according to the dilator assembly, the control handle comprises the moving part and the limiting part, the moving part is fixedly connected with the near end of the puncture needle, the moving part is used for driving the puncture needle to move in the axial direction of the moving part, and a user can control the puncture needle conveniently; the limiting step is arranged on the outer wall of the moving part, and the axial distance between the near end of the limiting part and the limiting step is 0.5-10 mm, so that the distance of a puncture needle extending out of the dilator can be limited, and the safety of puncture operation can be guaranteed.

The invention provides an optical imaging lens, the optical imaging lens has three lenses with focal power, and the optical imaging lens comprises a lens group, a bearing element group and a lens barrel, the axial distance T12 from the image side surface of the first lens to the object side surface of the second lens and the axial distance T23 from the image side surface of the second lens to the object side surface of the third lens meet the following conditions: 1.4 lt; t12 / T23lt; 2.0); the inner diameter d2m of the image side surface of the second bearing element, the inner diameter d1m of the image side surface of the first bearing element and the distance EP12 from the image side surface of the first bearing element to the object side surface of the second bearing element along the direction of the optical axis of the optical imaging lens meet the following conditions: 0.25 lt; (d2m-d1m) / EP12lt; and 1.5. The problem that miniaturization and high imaging quality of an optical imaging lens in the prior art cannot be considered at the same time is solved.

A wheel includes a boss, a rim, and a web. The rim includes a tread and a flange. A center of the rim in the axial direction of the wheel is disposed closer to the flange in the axial direction than a center of the boss in the axial direction is. The web has a plate-thickness center line that has a linear shape when the wheel is viewed in its longitudinal section. When an angle that the plate-thickness center line forms with the axial direction is denoted by a, a distance in the axial direction from a side face of the rim to an outer end of the plate-thickness center line is denoted by Pw, a length of the rim in the axial direction is denoted by Wr, and Pw / Wr is denoted by L, the wheel satisfies the expression L≥0.0223α−1.363. Where, the angle α is 90° or less.

The invention relates to an airbag, which is configured to be set from an uninflated state to an inflated state to protect an occupant of a vehicle. According to the invention, it is provided that the airbag has at least two fabric layers which are connected to one another in such a way that a central inflow region forming a first airbag chamber and at least two wing regions forming respective second airbag chambers and extending radially from the inflow region are formed, so that during the inflation operation of the airbag a gas can first flow into the central inflow region and then from the central inflow region into the respective wing regions, distal end portions of the at least two wing regions being connected to one another via a flat tensioning element, so that the distal end portions move axially away from the central inflow region during the inflation operation of the airbag and, in the inflated state of the airbag, radially tension the flat tensioning element at an axial distance from the central inflow region.

The invention discloses an optical imaging lens, which comprises a first lens group, a second lens group and a plurality of bearing pieces, the first lens group and the second lens group are sequentially arranged from an object side to an image side along an optical axis, and the first lens group is accommodated in a first lens barrel and comprises a first lens and a second lens; the second lens group is accommodated in the second lens barrel and comprises third to sixth lenses; the first to sixth lenses are sequentially arranged from the object side to the image side along the optical axis. A third bearing piece in contact with the object side face of the fourth lens is arranged between the third lens and the fourth lens, and a fourth bearing piece in contact with the object side face of the fifth lens is arranged between the fourth lens and the fifth lens. The maximum height LB of the second lens cone, the combined focal length F2 of the second lens group, the effective focal length f4 of the fourth lens and the distance EP34 of the third bearing piece and the fourth bearing piece on the optical axis; the on-axis distance SAG41 from the intersection point of the object side surface of the fourth lens and the optical axis to the vertex of the non-light-transmitting part of the object side surface of the fourth lens and the on-axis distance SAG42 from the intersection point of the image side surface of the fourth lens and the optical axis to the vertex of the non-light-transmitting part of the image side surface of the fourth lens meet the following conditions: 0.5 lt; lB / F2lt; 1.5, 1.6 lt, 1.5, 1.6 lt; f4 / F2lt; 1.8, and 0.5 lt; eP34 / SAG41 + SAG42lt, and SAG41 + SAG42 < 2.

The utility model discloses an optical imaging system. The optical imaging system comprises a lens cone, an imaging group and a second spacing element, wherein the imaging group and the second spacing element are arranged in the lens cone. The imaging group sequentially comprises a linear polarization film, a reflective polarization element, a quarter-wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer from the first side to the second side along the optical axis; wherein the first lens and the second lens are glued, and the third lens and the fourth lens are glued. The second spacer element is disposed on the second side of the second lens and is in contact with the second side of the second lens. Wherein the outer diameter D0m of the second side end face of the lens barrel and the outer diameter D2m of the second side face of the second spacing element meet the condition that D0m-D2m is larger than or equal to 4.51 mm and smaller than or equal to 5.8 mm; the inner diameter d2m of the second side surface of the second spacing element, the inner diameter d2s of the first side surface of the second spacing element, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy the following formula: (d2m-d2s) / T23 is greater than or equal to 0.97 and less than or equal to 2.79.

The utility model relates to a DMD welcome lamp lens with short total length, the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens from left to right along a light incident light path, the lenses are made of glass materials, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are glass spherical lenses, the second lens is a glass aspheric lens, wherein the third lens and the fourth lens, and the fifth lens and the sixth lens form a balsaming lens group. By reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the imaging performance requirement of the lens is met, the total length of the lens and the radial size of each lens are reduced, and a 33 mm lens group is formed.

The invention relates to a multi-stage centrifugal pump transition flow channel and a flow channel design method. The transition flow channel comprises a delivery chamber, a flow channel diffusion section and a suction chamber. An outlet of the delivery chamber located at the upper stage is communicated with an inlet of the flow channel diffusion section, and an outlet of the flow channel diffusion section is communicated with an inlet of the suction chamber; the delivery chamber is of a double-volute structure and is symmetrically arranged about the center line of the volute, and the sum of the areas of the two symmetrical throats is equal to the area of a single volute; the flow channel diffusion section obliquely penetrates through the pump body, the internal sectional area of the flow channel diffusion section is gradually increased in the direction from an inlet to an outlet until the sectional area is equal to or slightly smaller than the inlet area of the suction chamber, the flow channel diffusion section is symmetrically arranged about the center line of the volute, and the suction chamber is symmetrically arranged about the center line of the volute. The radial force can be basically balanced, so that the pump operates stably, and the noise and vibration of a unit are reduced; the radial size of the pump body is small and space is saved; the efficient range is wide; the axial distance of the transition flow channel is reduced, and the axial size of the pump body is reduced.

The invention discloses a planar interconnection connector and an integrated assembly, and belongs to the field of adapters. The first plug-in assembly is mounted on the first shell; the other side of the first shell is provided with a second shell, and the other end of the second shell is provided with a second plugging assembly. An adapter assembly is arranged on the inner sides of the first shell and the second shell; the outer side of the second shell is sleeved with an elastic piece, and the elastic piece abuts against the first shell and the second plugging assembly. When plugging is carried out, the second housing extends into the inner side of the first housing, and the switching assembly is stressed and compressed at the same time, so that the first plugging assembly and the second plugging assembly move oppositely along the same axis direction. The second shell shrinks to enter the inner side of the first shell, meanwhile, the switching assembly is stressed and compressed, the floating compression distance is formed through the two inserting structures, the compression stroke of 1 mm is guaranteed in the axial direction, and the large-axial-distance compression stroke is achieved under the condition that the inserting isolation degree is guaranteed.

Embodiments of a prosthetic valve delivery apparatus are disclosed. The delivery apparatus includes a first portion configured to maintain a fixed spatial relationship relative to a first end of the prosthetic valve and a second portion configured to maintain a fixed spatial relationship relative to a second end of the prosthetic valve during radial expansion of the prosthetic valve. The first portion includes one or more reference radiopaque markers and the second portion includes an indicator radiopaque marker. A position of the indicator radiopaque marker relative to the one or more reference radiopaque markers measures an axial distance between the first and second ends of the prosthetic valve indicative of a corresponding diameter of the prosthetic valve as it is radially expanded from a radially compressed state to a radially expanded state.

The invention relates to the technical field of grating detection, in particular to a non-contact grating positioning measurement platform and method.The non-contact grating positioning measurement platform is mainly composed of an axial distance measuring probe, a radial distance measuring probe, a multi-dimensional displacement adjusting table, an air floating rotary table and a control system; in the process that the air floating rotary table drives the grating to rotate, the axial distance measuring probe and the radial distance measuring probe periodically measure the distance between the axial distance measuring probe and the grating, and the control system generates an end jump error curve and an eccentric error curve according to measured data and controls the multi-dimensional displacement adjusting table in a closed-loop mode according to the end jump error curve and the eccentric error curve. And adjusting the levelness of the upper surface of the to-be-processed grating and the overlap ratio of the circle center of the to-be-processed grating and the rotation center. Non-contact measurement in the grating machining process is achieved, the problem that the grating can be damaged by traditional contact measurement is solved, and the method has extremely high application value in the actual machining process.

The utility model relates to a 3M five-piece type foresight main camera. The 3M five-piece type foresight main camera comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens and a fifth lens which are sequentially arranged from left to right along a light incident light path, the first lens is a meniscus negative lens, the object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the second lens is a biconvex positive lens, the object side surface is a convex surface, and the image side surface is a convex surface; the third lens is a biconvex positive lens, the object side surface is a convex surface, and the image side surface is a convex surface; the fourth lens is a biconcave negative lens, the object side surface is a concave surface, and the image side surface is a concave surface; the fifth lens is a biconvex positive lens, and has a convex object-side surface and a convex image-side surface. According to the utility model, the design is reasonable, the structure is simple, through reasonable distribution of the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the 3M imaging performance requirement of the five-piece lens is satisfied, the total length of the lens and the radial size of each lens are reduced, and the miniaturization of the lens group is realized.

The utility model relates to a low total length 8M foresight main camera. An optical system of the main camera is composed of a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from left to right along a light incident light path. The lenses are made of plastic and glass materials, the first lens, the second lens, the fourth lens, the sixth lens and the seventh lens are glass spherical lenses, the third lens and the fifth lens are plastic aspheric lenses, and the sixth lens and the seventh lens form a balsaming lens group. By reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the total length of the lens and the radial size of each lens are reduced while the requirements of a front-view wide-angle camera and a front-view narrow-angle camera are replaced by the low-total-length 8M ultra-wide-angle imaging performance of the lens, and the miniaturization of the lens group is realized.

The utility model discloses a gas layering diffuser and a preheating cavity. The gas layering diffuser is used for supplying gas to n layers of sub-cavities of equipment and comprises an inner pipe, an outer pipe, a top wall and a bottom wall, the inner pipe and the outer pipe are concentrically nested, the inner pipe forms a gas inlet port on one side of the top wall, the top wall seals an annular cavity between the first tail end of the inner pipe and the first tail end of the outer pipe, and the bottom wall seals the annular cavity between the first tail end of the inner pipe and the first tail end of the outer pipe. The bottom wall seals the second tail end of the inner pipe and the second tail end of the outer pipe, the inner pipe is provided with a first air hole array, and the outer pipe is provided with a second air hole array corresponding to the n layers of sub-cavities, and the radial distance between the second air hole array and the first air hole array is at least a preset angle; the axial distance between the first air holes in the first air hole array is decreased along with increasing of the distance from the air inlet port. According to the utility model, the gas supply uniformity of each layer of sub-cavity, the heating uniformity and the heating efficiency can be improved.

The present invention relates to a method for detecting a balloon catheter abutment pressure and a balloon catheter ablation system. The method comprises the following steps: determining, when the balloon catheter in an inflated state abuts against a tissue of interest and is thus axially compressed and / or laterally biased, an axial distance x between a proximal end and a distal end of a balloon body in the balloon catheter and / or an included angle α between an end axis of the proximal end and an end axis of the distal end of the balloon body using a proximal magnetic sensor and a distal magnetic sensor; and acquiring, according to a first corresponding relation between the known axial distance x and an axial abutment pressure of the balloon catheter and / or a second corresponding relation between the known included angle α and a lateral abutment pressure, the actual axial abutment pressure and / or the lateral abutment pressure by mapping of the axial distance x and / or the included angle α. Correspondingly, the balloon body of the balloon electrode assembly can be compressed and deformed in the axial direction and / or compressed and biased in the lateral direction of the balloon catheter. The present invention mainly solves the technical problem of detecting the abutment pressure of a balloon catheter.

The embodiment of the invention provides a silencer structure and a compressor, the silencer structure comprises a bottom cover structure, the bottom cover structure comprises a first side and a second side which are opposite to each other, and the wall surface of the first side is used for abutting against a flange part of an upper bearing structure of the compressor; the boss structure is arranged on the bottom cover structure; the transition part comprises a plurality of convex hull parts which are arranged at intervals in the circumferential direction of the bottom cover structure, at least one convex hull part comprises a first boss and a second boss which have different axial distances from the bottom cover structure, and the at least one first boss and the at least one second boss are adjacently arranged in the circumferential direction of the bottom cover structure; and a first exhaust hole is formed between the adjacent first boss and second boss. According to the technical scheme, under the action of the first exhaust holes, the impact direction of the airflow can be changed, and therefore the direct blowing impact force of the high-pressure refrigerant airflow on the rotor is effectively improved.

The invention discloses a modular robot joint, encoder reading head position adjustment mechanism and method for adjusting the position of an encoder reading head, the encoder reading head position adjustment mechanism is disposed on one side of the encoder reading head bracket, and includes a lower support and a upper support, the lower support and the upper support are connected to each other and positioned by a positioning connecting member, the upper support is pressed tightly against the lower support by a pressing connecting member, the encoder reading head is fixed to the upper surface of the upper support and is opposite to the encoder magnetic ring, the encoder magnetic ring is fixed to the motor shaft or the hollow shaft, the distance between the lower support and the upper support can be adjusted by adjusting the pressing connecting member and positioning connecting member, so that the axial distance between the reading head and the magnetic ring can be adjusted to a predetermined value, the processing accuracy of related parts on the dimensional chain is reasonably reduced, and the processing cost is reduced too, and the relative distance between the reading head and the magnetic ring is easy to adjust when the robot joint is assembled and debugged, thus achieving good technical results.

The invention relates to the field of optical lenses, and discloses a camera shooting optical lens which comprises a first lens with positive refraction power, a second lens with negative refraction power, a third lens with negative refraction power and a triangular prism with negative refraction power which are sequentially arranged from the object side to the image side. Wherein the axial distance from the object side surface of the first lens to the image side surface of the third lens is D, the optical total length of the camera shooting optical lens is TTL, the Abbe number of a glass lens of the camera shooting optical lens is vdi, the focal length of the camera shooting optical lens is f, the focal length of the first lens is f1, the axial thickness of the second lens is d3, and the axial thickness of the third lens is d5; the axial distance from the image side surface of the second lens to the object side surface of the third lens is d4, the combined focal length of the second lens and the third lens is f23, the curvature radius of the object side surface of the third lens is R5, the curvature radius of the image side surface of the third lens is R6, and the following relational expression is satisfied: 0.14 < = D / TTL < = 0.46; 40.00 < = vdi < = 82.00; 0.30 < = f1 / f < = 0.70; -32.08 < = f23 / (D3 + D4 + D5) < =-3.00; 1.40 < = (R5 + R6) / (R5-R6) < = 20.00.

The utility model relates to a slitting tool and a slitting device. The slitting tool comprises a first cutter assembly and a second cutter assembly, the first cutter assembly comprises a first cutter shaft, a first adjusting spacer bush, a second adjusting spacer bush and a first cutter, the first adjusting spacer bush and the second adjusting spacer bush are sequentially arranged in the axial direction of the first cutter shaft and abut against each other, and the first adjusting spacer bush and the second adjusting spacer bush abut against each other through two spiral faces which are opposite in rotation direction and can be attached to each other; the second cutter assembly comprises a second cutter; the second adjusting spacer bush can rotate relative to the first adjusting spacer bush, and drives the first cutter to move in the axial direction of the first cutter shaft under the action of the first adjusting spacer bush so as to adjust the axial distance between the first cutter and the second cutter. The slitting tool and the slitting device have the advantage of being easy to operate.

Provided is a solenoid comprising a molded coil, an anchor, and an armature. In the anchor, an outer peripheral convex portion and an inner peripheral convex portion are formed. When no current is being applied, axial distance between the outer peripheral convex portion of the anchor and an outer peripheral portion of the armature which is radially closest to the outer peripheral convex portion is smaller than axial distance between the inner peripheral convex portion of the anchor and an inner peripheral portion of the armature which is radially closest to the inner peripheral convex portion. In other words, timing at which the outer peripheral convex portion of the anchor and the outer peripheral portion of the armature face each other in a radial direction is shifted from timing at which the inner peripheral convex portion of the anchor and the inner peripheral portion of the armature face each other in the radial direction.

The invention relates to the technical field of aircraft propulsion systems, in particular to a special-shaped air inlet lip for an on-wing integrated distributed propulsion short cabin unit. The lip is located at the starting part of the air inlet section and is defined by an upper lip, a lower lip, a left lip and a right lip; the inner surface of the upper lip is arc-shaped; the inner surface of the lower lip is linear and is smoothly fused with the upper surface of the wing; the inner surfaces of the left and right lips are curved surfaces with curved sweep characteristics, and the lower half parts of the left and right lips are in an inward-contracting shape; the length of the air inlet channel is defined as the axial distance from the foremost edge of the upper lip to the section of the inlet of the ducted fan and is not greater than the fan diameter D; a first rectification area and a second rectification area are arranged in the air inlet channel to optimize a flow field. Through the fusion design of the special-shaped lip and the wing and the compact air inlet channel, the requirement for compact integrated layout on the wing is met, meanwhile, the additional resistance of the nacelle is effectively reduced, the total pressure recovery coefficient not lower than 0.9 and the flow coefficient larger than 0.8 are guaranteed, and uniform and stable high-quality air inlet is provided for the ducted fan.

The invention discloses a nanosecond pulse hollow cathode electron beam current evaluation system, which aims at the problem of limited capacity of a current satellite communication channel, researches a nanosecond pulse high-current electron beam for driving a terahertz radiation source, and measures electron beam current and energy density distribution. The device is fixed on a four-axis motion platform through a Faraday cup with a slit hole, and the four-axis platform comprises an x axis, a y axis, a z axis and an R axis. Under the driving of the four-axis platform, the nanosecond time response Faraday cup can rotate around the z axis and sweep the section of the electron beam at a certain rotation angle in the direction perpendicular to the slit, and accordingly parallel projections of the electron beam at different angles are obtained. And current density distribution of a certain section of the electron beam is obtained through a filtering back projection algorithm program of the computer. On the basis, the three-dimensional density distribution of different energy electrons is obtained by changing the axial distance and the electron energy screening voltage, and then the time-space domain distribution of the electron beam energy density is obtained.

A valve assembly is disclosed that has a valve housing including a first axial end, a cap, a second axial end, and an airflow pathway extending from the first axial end towards the second axial end. The cap is positioned towards the second axial end. The valve housing includes an environmental opening configured for fluid communication with an outside environment, an enclosure opening towards the first axial end configured for fluid communication with an interior of an enclosure, and a film having an expansion diameter disposed in the valve housing laterally across the airflow pathway. The cap has an inner lateral surface and a piercing protrusion (having a piercing tip) extending from the inner lateral surface towards the first axial end. An axial distance is defined between the film and the inner lateral surface. A ratio of the axial distance to the film expansion diameter is at least 0.14.

The invention discloses a direct current brushless motor and a processing system thereof, and belongs to the field of assembling equipment, the direct current brushless motor comprises a workbench, an assembling area is arranged at the upper end of the workbench, a clamping mechanism and an assembling mechanism are arranged in the assembling area, the clamping mechanism and the assembling mechanism are arranged at intervals in the axial direction of a workpiece, and the assembling mechanism comprises a support. The support moves in the axial direction of a workpiece, a rotating part, a driving rod and an assembling driving mechanism are arranged on the support, the rotating part is arranged in the axial direction of the workpiece, the rotating part is driven by a workpiece rotating motor to rotate around the axis of the workpiece rotating motor, and a connecting mechanism used for being connected with the workpiece is arranged on the rotating part; the driving rod moves in the radial direction of the workpiece and extends towards the side of the clamping mechanism. And the assembly driving mechanism drives the pushing part to move in the axial direction of the workpiece. The invention aims to provide the direct-current brushless motor and the processing system thereof, and the labor intensity of workers can be reduced.

The invention relates to the field of optical lenses, and discloses a camera shooting optical lens which is composed of a first lens, a second lens, a third lens, a fourth lens and a prism which are sequentially arranged from the object side to the image side. The focal length and the total optical length of the shooting optical lens are f and TTL respectively, the focal length of the first lens is f1, the combined focal length of the front two lenses is f12, the combined focal length of the rear three lenses is f234, the central curvature radiuses of the object side surface and the image side surface of the first lens are R1 and R2 respectively, the axial thicknesses of the first lens and the third lens are d1 and d5 respectively, and the central curvature radiuses of the object side surface and the image side surface of the third lens are R1 and R2 respectively. The axial distance from the object side surface of the first lens to the image side surface of the fourth lens is Td, the distance from the maximum effective aperture position of the object side surface of the third lens to the maximum effective aperture position of the image side surface of the third lens in the direction parallel to the optical axis is ET3, and the following relational expression is satisfied: f1 / f is greater than or equal to 0.30 and less than or equal to 0.70; f12 / f234 is greater than or equal to-1.40 and less than or equal to-0.426; -3.00 < = R1 / R2 < =-1.00; 0.16 < = Td / TTL < = 0.21; and 0.05 < = d5 / ET3 < = 0.66.

A threaded connection for pipe in which the axial distance between the box intermediate shoulder surface and the box end shoulder surface of the box before make-up, LB, is larger than the axial distance between the pin intermediate shoulder surface and the pin end shoulder surface of the pin before make-up, LP, such that, upon completion of make-up, the pin and box intermediate shoulder surfaces and are in contact and function as torque shoulders, while the pin and box end shoulder surfaces are in light (or no) contact. The difference between the axial distances, (LB−LP), is such that, when the pin and box are made up and upon application of an axial compressive load, the pin and box are slightly axially compressed by the compressive load and the pin end shoulder surface comes into pressure contact with the box end shoulder surface to bear part of the compressive load.

The invention relates to the technical field of medical instruments, in particular to a dose adjusting mechanism of an injection device and the injection device. The push rod part penetrates through the holding part and is in threaded connection; the push rod part is sleeved with the transmission tooth part and limited in the circumferential direction, and the push rod part can move in the axial direction relative to the transmission tooth part. The transmission tooth part comprises a driven ratchet; the driving rod part can be switched from an initial position to an end position, and at the initial position, the driving ratchet and the driven ratchet are spaced in the axial direction and staggered by a preset angle in the circumferential direction; at the ending position, the driving ratchet is meshed with the driven ratchet, and the transmission tooth part rotates by an angle of one driving ratchet; the reset part drives the driving rod part to return to the initial position when the pressing force is released. The rotation angle of the transmission tooth part corresponds to the axial displacement of the push rod part, rotation of the transmission tooth part is discretized through one-by-one meshing of the driving ratchets and the driven ratchets, the single displacement of the push rod part is smaller, and the small-dose injection requirement is met.

An optical lens system for photographing, comprising four lens elements (E1, E2, E3, and E4), the four lens elements (E1, E2, E3, and E4) being, in order from an object side to an image side along an optical path, a first lens element (E1), a second lens element (E2), a third lens element (E3), and a fourth lens element (E4), each of the four lens elements (E1, E2, E3, and E4) having an object side surface facing the object side and an image side surface facing the image side; wherein the first lens element (E1) has a positive refractive index, the object side surface of the first lens element (E1) being convex in a paraxial region thereof, the second lens element (E2) having a positive refractive index, the object side surface of the second lens element (E2) being convex in a paraxial region thereof, the third lens element (E3) having a negative refractive index, the image side surface of the third lens element (E3) being concave in a paraxial region thereof, the image side surface of the fourth lens element (E4) being convex in a paraxial region thereof, and at least one surface of at least one lens element in the optical lens system for photographing has at least one inversion point (P); wherein an axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, wherein an axial distance between the image side surface of the fourth lens element (E4) and an image surface (IMG) is BL, wherein a focal length of the second lens element (E2) is f2, wherein a focal length of the fourth lens element (E4) is f4, wherein a central thickness of the first lens element (E1) is CT1, wherein a central thickness of the second lens element (E2) is CT2, wherein a central thickness of the third lens element (E3) is CT3, wherein a radius of curvature of the object side surface of the first lens element (E1) is R1, wherein a radius of curvature of the object side surface of the third lens element (E3) is R5, and wherein the following conditions are met: 0.05 < TD / BL < 0.60 ; 0.05 < | f 2 / f 4 | < 1.50 ; 0.10 < ( CT 2 + CT 3 ) / CT 1 < 1.00 ; and − 4.50 < (R 1 − R 5 ) / (R 1 + R 5 ) < 0.25.