A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check Valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow. Check Valves, Water Check Valves, Brass Check Valves, Sanitary Check Valves ZHEJIANG KINGSIR VALVE CO., LTD. , https://www.kingsirvalve.com
Research on the deviation control of transmission belt of metal belt type continuously variable transmission. Wu Fahong (Department of Automotive Engineering, Shandong Jiaotong University, Jinan Shao, several methods to eliminate the axial deviation of transmission steel belt, and pointed out the use of curved bus pulley or change There is no shortage of control methods such as speed ratio when there is no deviation. For this reason, an electro-hydraulic control method is proposed, which has achieved good results in eliminating the axial deviation of the transmission steel belt.
The metal belt type continuously variable transmission (metal belt type CVT) is a continuously variable transmission mechanism in which a metal transmission steel belt is a key component thereof, and the dynamic performance of the transmission steel belt determines the working performance and efficiency of the continuously variable transmission. The axial deviation of the metal strip is the inevitable result of the specific shifting mode of the metal belt CVT. The axial deviation of the metal strip will cause the belt and the pulley to slip and additionally wear, consuming additional energy and directly affecting the metal. Belt CVT drive performance and transmission efficiency. The author uses the method of numerical analysis to verify and solve the axial deviation and its size of the metal strip, and points out the shortcomings of the control method such as using the curved bus pulley or changing the speed ratio without deviation. The hydraulic control system eliminates the axial deviation of the drive belt and improves its dynamic performance.
1Metal belt type CVT transmission steel belt axial deviation analysis Automotive metal belt CVT transmission pulleys generally adopt straight busbar pulleys, and both adopt a single movable pulley shifting mode, and the main driven pulleys each have a movable cone Wheel and fixed cone wheel, two fixed cone wheels are arranged oppositely, two opposite movable cone wheels move in the same direction, when the movable pulley movable cone wheel moves 2Cp axially, the driven pulley movable cone wheel moves in the same direction axially 2CS At the same time, the main and driven ends of the steel strip move CP and Cs in the same direction respectively. Since Cp and Cs are not always equal, the axial deviation of the belt is generated, as shown.
Since the elastic modulus of the steel strip is large, the elastic elongation of the steel strip after the force is ignored, and the geometric length of the steel strip is kept constant during the shifting process; and the geometric relationship between the deformation of the metal block and the cone wheel is ignored. Influence, assuming that the arc of the steel strip and the pulley is the ideal arc.
Fund Project: Shandong Science and Technology Plan Project â–² Metal Belt CVT Transmission Steel Belt Axial Distance Deviation Calculation Diagram The basic geometric relationship in the calculation of the axial distance deviation of the transmission steel belt with available metal belt CVT, as shown. The unique curved busbar makes the steel transmission ratio fâ–² three different curved busbar pulleys to reduce the axial deviation of the steel belt. It can be seen that the Hendriks curved busbar (curve 1) can fully compensate. The effect of the deviation of the steel strip can theoretically make the axial deviation 0. In fact, due to the influence of machining errors and other factors, the axial deviation is not 0. The arc curved bus pulley (curve 2) also has The good depolarization effect, the maximum axial deviation of the steel strip is only 0.0012mm, which basically eliminates the axial deviation of the steel strip. Although the curved busbar pulley has better depolarization effect, it is difficult to process and has high manufacturing cost. In addition, when the curved busbar pulley has different speed ratios during the transmission process, the pulley groove angle changes, so that the metal belt and the pulley are changed. The contact area is continuously reduced, directly affecting the reliability of power transmission.
2.2 By adjusting the speed ratio to eliminate the axial deviation of the book6 pieces to the fixed end of the pulley to move dc, so that the movable end of the pulley moves to the left for 2d. The center line of the steel strip moves dc to the left, and the deviation of the steel strip is compensated for the heart.
In order to eliminate the axial deviation C of the belt, the method of the curved busbar is adopted, and the main driven wheel is corrected for C/2. If the coordinate system is established, the coordinate origin is set at r/mi, r, sm, and the pulley bus is set. The coordinates are (x, y).
The curved busbar pulley has a good effect of reducing the axial deviation of the steel strip, but due to the difficulty in processing, the straight busbar pulley is often used in actual use. In the stepless variable speed transmission process, the axial deviation of the transmission steel belt is usually controlled by the following methods: 1 time, the deviation C = 0, the axial deviation of the transmission steel belt at the limit transmission ratio position is the largest, the maximum value Slightly less than 1mm (when the curve speed ratio i = 1, the preset one axial distance offset C = half of the maximum deviation amount / account book8 is the metal belt type continuously variable transmission test test system frame drive The axial offset test curve of the steel strip is based on the test apparatus of the metal belt type basket transmission ratio control system. The maximum value of the axial runoff amount of the ublishingHouse.Allrights is reduced by half (curve C).
For a moment, let C = 0. One is the speed ratio when the car engine sends the maximum power to make the car reach the highest speed. At the time of design, the center lines of the V-grooves of the main and driven pulleys are coincident at i= (curve B).
â–² Calculation curve of the influence of different configurations of the straight busbar pulley on the axial deviation. The above method only ensures that the axial deviation of the transmission steel belt is zero at a certain working point. In fact, the working condition of the car is variable, so by adjusting the speed ratio, the axial deviation of the transmission steel belt cannot be reduced or eliminated from time to time.
2.3 Designing a new electro-hydraulic control system to eliminate the axial deviation to completely eliminate the axial deviation of the metal belt CVT transmission steel belt. This paper designs a new metal belt CVT electro-hydraulic servo control system, which can drive the transmission. In the process, the position of the movable cone of the main and driven pulleys is detected in real time, and the position of the movable cone wheel can be adjusted in time to eliminate the axial deviation of the transmission steel belt. The electro-hydraulic servo control system of the metal belt type CVT is mainly composed of a speed ratio feedback control system and a position feedback control system, as shown in the figure. 161. The speed ratio control system mainly consists of an electro-hydraulic proportional reversing valve 2, a driving reel movable cone wheel Cylinder (referred to as active cylinder) 3, driven pulley movable cone wheel cylinder (referred to as driven cylinder) 8, speed sensor 1, and other components; position feedback control system mainly by electro-hydraulic proportional reversing valve 2, active cylinder 3, The driven cylinder 8, the position sensor 4, and the like are composed. The position feedback control system and the speed ratio control system share a set of power mechanisms. The pressure of the system is set by the electro-hydraulic proportional relief valve 6. The electro-hydraulic proportional relief valve, the electro-hydraulic servo valve, the speed sensor, and the position sensor are all supported by the on-board computer. control.
During operation, the operating pressure of the entire oil circuit is controlled by the on-board computer to control the set pressure of the electro-hydraulic proportional relief valve, and the maximum working pressure is limited. The high-pressure oil generated by the hydraulic pump provides a reliable clamping force to the driven cylinder all the way; the other through the electro-hydraulic ratio reversing valve to the active cylinder for speed ratio control and position control. During the work, the speed sensor 1, the detection of the driving speed of the driving pulley and the passive pulley, after processing by the onboard computer, sends a control command to the electro-hydraulic proportional reversing valve to control the speed ratio to rise and fall. Then, the position sensors 4 respectively detect the displacements 2CP and 2C.S of the movable pulley movable cone and the driven pulley movable cone, respectively, via the onboard computer, and compare the sizes of the two, and then the deviation signal 2 (CP) +Cs) becomes an electric signal, and is amplified as a feedback signal to form a position feedback control system to control the electro-hydraulic proportional reversing valve, so that the active cylinder moves by -2 (Cp+Cs) to eliminate the axial deviation of the transmission belt. .
It can be improved to meet the requirements of position control and axial deviation test of transmission steel strip.
It is the axial offset test test curve of the transmission steel belt under different speed ratios. It can be seen from the figure that the designed electro-hydraulic control system can significantly eliminate the axial deviation of the transmission steel belt, thereby improving the transmission performance of the metal belt type continuously variable transmission, reducing the wear of the transmission steel belt, and extending the steel. The service life of the belt.
6 Conclusion Combined vibration processing can reduce the drilling force and extend the service life of the tool. The tool can be used for a period of time without trimming.
Since the relative speed of the tool and the workpiece is higher than the vibration of the workpiece, the abrasive particles continuously impact and scratch the surface with great speed and acceleration, and the material of the working area is pulverized into small particles and removed from the workpiece. Enhances the crushing effect of the workpiece. Thereby increasing the removal rate of the material.
The removal rate and surface roughness of a general material are a pair of contradictions, and in this case, although the removal rate of the material is increased, the roughness does not change much.
Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.
There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with Ball Valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.
A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank Drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the backwater valve (for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.
A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
An in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.
A duckbill valve is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
A pneumatic non-return valve.
Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
Research on Deviation Control of Transmission Belt of Metal Belt Type Continuously Variable Transmission