How to choose the water pump, in fact, a submersible pump and water pump, it can be used in the industry from many aspects to see, in the city's drainage, it gives us residential buildings or buildings to provide water pressure, gardens and fields, and give some heating equipment to increase the pressure have a great effect. It delivers water to the equipment or a liquid medium similar to that of clean water.

In many units, will use the water pump, so the problem is how to choose the appropriate water pump, in order to make efficiency reach the highest level, this is a lot of units need to know the problems of water pump and the submersible pump is what is the difference? Where is the water pump and diving on? The two pump sound similar to pump, the difference in where, let us look at the next.

The difference between submersible pump and clean pump is that:

First, compared to the water pump, submersible pump is arranged to work under the water, and the water pump can be used outside of the water, although their structural characteristics are the same, but the sewage pump head is not high, because there are many dirty things in the sewage, submersible pump, water pump impeller than pore the sewage pump to be big, prone to problems, and measurement of diaphragm pump is the same as the ordinary, are from sewage, so the impeller friction.

Second, water pump centrifugal pump is classified in the category, of course, the structure and measurement of diaphragm pump is little difference, while the water pump is generally in order to complete higher efficiency at work, extracting more sewage, so the design is efficient, with water stress optimal structure parameters.

Third, let us say the structure of water pump, the impeller is a device that everyone is familiar with, if it is ordinary sewage pump, the impeller is very simple, not that can block retainer of pollutants, the impeller gear also can be flexibly regulated range. Therefore, the pump with special structure will not exceed the efficiency at the same time.

Why a lot of submersible pump efficiency is lower than the water pump, sewage pump and because they like the medium flow through a wider, thus can reduce the transmission efficiency, in order to prevent clogging sewage pump inside, have to do so. In general, the difference between clean water pumps and submersible pumps is their installation.

The difference between water pump and finished the submersible pump, so we want to know their role in their respective? Submersible pumps and metering diaphragm pump is generally different ordinary pumps are working on the ground, and it is working under the water, the water pump and the submersible pump can not be used to discharge water in. Before work, to ensure the full amount of the water pump, submersible pump in agricultural irrigation, drainage to the city, so as to achieve the purpose of transporting liquid, and has a large conveying capacity in textile and papermaking industry.

Practical technology * transmission rear cover assembly technology of bearing assembly Yan Cangfeng (Shaanxi Fashite automobile transmission Co. Ltd., Shaanxi Xi'an 710077) quality and reduce the labor intensity of the back cover assembly modification of mechanical bearing pressing technology. Through the analysis of several bearing assembly schemes, a better technical scheme for bearing press assembly is selected, and the corresponding design of press mounting fixture is introduced.

Bearing; assembly automobile transmission back cover assembly bearing assembly by manual smashing way, has been unable to meet the requirements of modern enterprise development. First of all, by manually hitting the bearings, smashing the strong impact will increase the bearing and the back shell damage, affecting the quality of the transmission assembly. Secondly, by manual crushing into the way of bearing, the labor intensity of workers is large, noise is great, and environmental pollution is caused. Therefore, the bearing assembly of the rear cover assembly is technically reformed and the bearing is assembled by mechanical pressing.

1 bearing assembly description bearing assembly for transmission rear cover assembly such as. The assembly process is as follows: A. shaft box assembly 2 side pieces on the assembly mould positioning hole;. Place synchronizer;. Install the bearing of the vice case, the main shaft, the auxiliary box, the reduction gear and other accessories. 3 bearing center "shaped into convex combination bearing 2 high stern bearing 1 in a straight line (2 X and Di in a vice spindle box!

On plane. Manual assembly is to install two bearings on both sides (for positioning), and then install the intermediate combination bearings. The first pressing pressure on both sides of the two bearing rolling intermediate bearing or combination of 3 bearing and pressing mode.

2 demonstration program according to the characteristics of the rear cover assembly bearing assembly, puts forward 2 kinds of press plan, namely three beam four column type compressor (rod structure scheme of Hunan C shaped special press (scheme two) for a workshop cover assembly line using the ring rail line, the number of units in the ring rail car assembly line operation cycle. On the basis of the existing ring track production line, the rear cover assembly car is reformed to meet the requirement of press positioning. The press adopts three beam four post type pull rod structure (such as), the body is sunk in the ground, and the auxiliary table plate is leveled with the original line body. Work with fashion cars loaded by the pressing piece mounted (shaft, bearing and shell) by line track, pushed to the compressor auxiliary table limit rail to maintain the original car running track, press the elastic pre positioning device early positioning assembly trolley bearing assembly trolley wheels so that the car picked up without pressure, press start position the guide rod two position, press the bearing in place of pressing yuan, loosen the pre positioning device assembly car sent to the next station.

2.2 in the original scheme of two ring rail production line based on the transformation of C shaped cover assembly trolley press with C - special press) work, such as -18- automobile technology and material table I scheme scheme two compressor structure three four beam rod structure of the press C - special press tetrastyle four C four wheel car wheel assembly assembly trolley assembly trolley car chassis side through press stop guide; there is a hole in the bottom of the chassis; and the pre positioning hole and the trolley table two positioning guide rod hole with high position accuracy requirements of high precision, great difficulty in processing the initial positioning trolley and limiting device with slot car; and fixture for large gap with two times by the positioning fixture to ensure the processing precision low, easy processing and low cost at the beginning of two positioning positioning mechanism: elastic pre positioning device, automatic limit for solution In addition to the positioning guide rod positioning assembly car cylinder stopping device: the sensor detects the car automatically after the limit, automatic lift lifting positioning device push rod positioning fixture pressing force force force car assembly fixture, assembly trolley force cutting line installation guide needs digging pit installation construction, long construction period of production direct installation, without breaking the line, do not dig the pit; installation short construction period does not affect the production oriented vertical rod (4) pressing positioning fixture table trolley assembly trolley guide post guide rail (both sides) two limit line guide rail auxiliary table bearing bearing (two rows * 'pre positioning device of T assembly program the car was installed on the pressing workpiece body guide rail under the action of pushing the car to the compressor cylinder limit device after inducing signals automatically lock the car at the beginning of the positioning assembly. Start pressing press bearing placed below the lifting cylinder positioning fixture so that the car to pick up the boost, not pressure while the two push rod two positioning clamping fixture for machine head lifting in place return return press positioning oil cylinder limit device automatically release the press fit into Chinese push to the next station car bearing under pressure head.

Comparison of two schemes of two 2.3 of the two programs is shown in table 1. Table 1 through the comparative analysis, considering the press positioning, assembly trolley structure, pressing force, processing and installation of construction cost factors such as positioning scheme two is simple and reliable, low processing cost, short construction period, no installation the advantages of the production plan of two.

3 press fixture design, design, improved tooling, such as. The press installation adopts the way of lower positioning, and requires that the press head on the press and the lifting rod of the lifting device at the lower position have higher position requirements. When the compressor automatic first positioning assembly trolley lifting device to pick up or cylinder positioning rod by pressing fixture two under positioning hole two positioning clamping fixture, clamping fixture on 3 axis positioning holes of the positioning of two side spindle box and an auxiliary box, so as to ensure the 3 shafts and bearings respectively and the pressure head 3 have a coaxial, head hole left a larger gap to ensure the press axis and no interference. The press fixture is picked up with the assembly dolly during press mounting

Hydraulic control valve in addition to fill oil loop used in balance, order, packing, and often used in fixing a vertical hydraulic cylinder (load) or push rod movement as well as the implementation of the directional control valve lift logic element, which is often the hydraulic control valve is an important component in hydraulic system to meet the requirements of the characteristics of the load causes, control effect of other components is irreplaceable.

In the pressure system, the hydraulic control check valve achieves logical directional control. It needs a good opening pressure characteristic, the opening pressure, the time delay change is small, and the instantaneous opening is sensitive. In the self holding system, the load should be kept in the stop position for a long time, and the piston (load) can be locked in any position, and the hydraulic check valve should have reliable locking and locking position accuracy. Sometimes in a system, it also requires good open and locked pressure control characteristics. Opening and locking are important characteristics of the hydraulic control check valve in the application of the control circuit.

2, open the locking pressure control characteristic analysis of hydraulic system with single piston hydraulic cylinder as the actuator, the different installation positions of different cavity as the main working chamber and a hydraulic control valve in the circuit, the circuit performance are very different, especially the opening and locking characteristics of the system have different changes. Taking the pressure system and the load self retaining system as an example, the different opening and locking pressure characteristics are analyzed by the common oil inlet and return circuit system. Two system hydraulic cylinder geometry parameter 2.1 enters the oil way application characteristic analysis to show, the load self maintenance system widely applies in the balance circuit, the locking loop and the pressure maintaining and so on in the loop. The balance circuit can be regarded as vertical placement of hydraulic cylinders. The throttling valve indicates the return resistance, and the hydraulic control check valve has one end of the rod cavity in the hydraulic cylinder.

The oil inlet requirements of check valve in the hydraulic cylinder vertical and vertical motion of parts due to weight and self fall, stop or slow down the piston piston due to weight and accelerate whereabouts; or the hydraulic cylinder is fixed on any position, to prevent the hydraulic cylinder because of high load and reduce the pressure of the loop movement. The characteristics of the pressurization (intensification) and the no-load control pressure of the system have been analyzed and the results are given. The characteristics of the pressure control of the opening and locking are analyzed as follows.

Bachelor degree, mainly engaged in fluid transmission and control research.

Hydraulic and pneumatic opening pressure depends on the pilot control pressure control, pressure from the top of the load in the single self maintenance system, the N value must be greater than 1. to open the valve, reverse flow of oil, the mechanical characteristics of circuit equation: describes the opening and locking control valve characteristics, N value is not too small, A\ the hydraulic cylinder piston rod m2 area, Ar area, M2 K per unit area of the spring force, the control piston area of NAc valve, M2 A2 core confined area in M2 solution (1) a Ar hydraulic control valve leakage control is small regardless of the piston, the pilot control pressure Pc*K hydraulic control valve is not open and by the formula to calculate the minimum limit value of available N critical formula, otherwise the valve opening is required to control the pressure higher than the required pressure caused by unsafe factors system. The R ratio is also an important parameter, which describes the mechanical characteristics of the system in conjunction with the N value. The determination of the R ratio, on the one hand determines the size of the hydraulic cylinder, on the other hand, it also indirectly affects the opening and locking performance of the valve. In the hydraulic system, when the piston rod is pulled, it is usually 3.33. When the pressure is high, the small value is taken; when the pressure is low, the big value is taken. When the piston rod is pressed, consider the stability of the piston rod, generally take D/d=1.33 ~2., if the hydraulic cylinder stroke speed is larger, in order to prevent hydraulic impact, special design should be carried out.

The return line opening and locking system figure K value is generally 140kPa, system parameter type (2) analysis steps can N open analysis of =2.667:1 2.2 oil application characteristics of the system has shown similar to the oil inlet system, the mechanical properties of the equation: with the same, the system parameters of type (3) to N open the two = different working system, need to use a different hydraulic control valve or adjust the different pilot control pressure. When the 1 conditions used in pressure system, open the N value must be greater than 2667:1; when the condition 2 using 3 conclusions based on the pressure system and the load from N and R analysis system is established to maintain, measure and evaluate the hydraulic control valve to open and lock the pressure control characteristic of the important parameters and basis. General industrial hydraulic cylinder R range 1.75~ 10, even if there are special conditions, the value should not be less than 1.15, because the low R value will increase the N value. The general N range is 1. 5:1~4:1, even if the R is close to the limit value, the N value should not be too much, beyond the range of values. In practical application, the hydraulic control check valve, which is closest to the theoretical calculation value, can better meet the system requirements.