Solenoid for valve control is an important element of the control of electromagnetics valve. The wet-type solenoid produced by Bso co. is a typical type Bsoch solenoid on the market. As a regular Bsoch solenoid supplier, KaiDi can produce on-off solenoid, proportional solenoid, explosion-proof solenoid or custom solenoid. Kaidi provides this analysis for learning Bsoch solenoid fully. This paper introduced the features of structure, static attraction force, temperature rise, withstand of oil pressure and etc.
History of solenoid in China
Hydraulic solenoid is a key actuator of solenoid valve. The structure and property of hydraulic solenoid not only affect the quality, but affect the hydraulic system and whole machine. China has produced solenoid for control valve since 1996. The first series of solenoid of China include MFJ1 and MFZ1 dry-type solenoid, which is designed according to foreign sample.
Because the shorts of dry-type solenoid like poor sealing, leaking hydraulic oil and short service life, in the 70s, wet-type solenoid came into being in foreign countries. The wet-type solenoid means pressure oil is allowed to enter magnetic cavity, and seal form change from motive seal into static seal. The wet-type solenoid has great improvement in sealing and use life, so it was widely applied in many areas. In the late 1970s and early 1980s, China developed MFZ1-YC series solenoid and MFB1-YC series solenoid.
In addition to, some foreign countries develop wet-type solenoid with plastic package. For increasing the manufacturing level of hydraulic elements, China introduced technology from German and America. As a leader of solenoid manufacturer, Bsoch solenoid has so many technologies in structure, property to analysis.
Structure of Bsoch solenoid
AC solenoid and DC solenoid are two typical types of solenoid, they have difference in power system and other aspects.
DC solenoid
The shell and concentrating flux plate of solenoid both are punching parts, their contacts weld together. DC solenoid processing is relatively easy. At the design time, reduce the space volume of shell and increase the style of appearance. The shell, concentrating flux plate and coil are combined with plastic package, which is helpful for improving work efficiency, save cost and reliability.
The flux sleeve of solenoid consists of two parts, both sides of solenoid is made of permeability magnetic material, the middle part is made of non-magnetic material. To prevent suction between sidewall of flux sleeve and sidewall of iron core, and reduce the side frictional force, Bso Company set a non-magnetic stainless steel tube in the flux sleeve.
For large-scale solenoid, Bso puts two eccentric circular rings on armature, and eccentric circular ring is made of non-magnetic materials. Two eccentric circular rings have smooth appearance and reduce friction. The gap between armature and retaining iron is cup-type section.
AC solenoid
AC solenoid from Bso is novel. The magnet yoke of small-large solenoid is made of silicon steel sheet, roll steel sheet into a round shape, put coil and two concentrating flux plate together. The magnet yoke of large-scale solenoid use special way to pile silicon steel sheet. As for specific processing, firstly, making plastic skeleton of coil into special shape that is useful for stack of silicon steel sheet. Secondly, assemble magnet yoke and package with plastic. This kind of structure avoids riveting pressure and reduces power loss.
In order to reduce eddy-current loss, guide sleeve, armature and retaining iron of solenoid are all made of silicon steel with high resistivity.
Performance analysis of Bsoch solenoid
Performance patameter of solenoid at home and abroad
| Model | Rated Stroke(mm) | Rated Force(N) | Power loss(W) | Service life(times) | Economic Weight Ratio(kg/N.m) | Static Oil Pressure (Mpa) |
| *MFJ 6-17 YC | 2.8 | 17 | 24 | 10×106 | 7.5 | 1 |
| MFJ 2-2.5 YC | 2.8 | 24.5 | 26 | 10×106 | 9.0 | 6.3 |
| *MFZ 6-.22 YC | 2.8 | 22 | 26 | 10×106 | 5.0 | 16 |
| MFZ 1-2.5 YC | 3 | 24.5 | 26 | 6×106 | 8.0 | 6.3 |
| *MFJ 6-54 YC | 3.6 | 54 | 40 | 10×106 | 6.4 | 16 |
| MFJ 2 – 4 YC | 3.6 | 40 | 38 | 10×106 | 6.9 | 6.3 |
| *MFZ 6- 87 YC | 3.6 | 87 | 35 | 10×106 | 5.5 | 21 |
| MFZ 1-7 YC | 3.7 | 70 | 38 | 6×106 | 4.5 | 6.3 |
tips: the model with”*” is the Bosch solenoid, and the rest are the domestic solenoids.
Static Suction Characteristic
Due to the load of the hydraulic solenoid is spring, in order to use the hydraulic solenoid along with the spring, the static suction characteristics of the solenoid is designed to be higher than 30% the spring force.
The main structure factor which influences the static suction characteristics of the DC solenoid is the shape and the structure parameter of the working gap. We can get the ideal static suction characteristics through changing the structure parameter of the working gap reasonably.
BSO’s DC solenoid has a greater icon core and the armature parameter. The characteristic curve of the DC solenoid is smooth and has a rising trend. Besides, the DC solenoid uses well along with the spring force characteristic of the valve.
The AC solenoid is different from the DC solenoid. The AC solenoid suction characteristic is depending on the magnetic field structure parameter rather than the working gap. Considering the iron loss and the loss of the short-circuit ring, the mean attractive force AC solenoid is smaller than the DC solenoid In the case of the same dimensions and excitation power.
In terms of the characteristic curve shape, the solenoid at home and abroad is similar. In terms of the Economic weight ratio, BSO solenoid is smaller than the foreign solenoids, nearly 7-30%. So the BSO solenoid is much cheaper than the foreign solenoid.
Temperature Rise Characteristic
Insulation grade of Bsoch solenoid reach F level and the allowable temperature is 155°c. The solenoid uses the overall plastic package and the low cover can deliver the heat directly, so the heat dissipation performance is better.
According to a test, the maximum temperature is lower than 135°c, so the solenoid is a safe product.
In contrast, the domestic solenoids insulation grade is B Level which allowable temperature is 130°c, and the maximum temperature is 125°c.
Oil resistance performance
For the wet-type solenoid, the pressure oil can enter flux sleeve, so the flux sleeve should have the oil resistance performance. Considering this character, BSO Company designs the structure. Firstly, they add a stainless steel pipe to the flux sleeve in order to increased oil pressure resistance. Secondly, for different solenoids, BSO Company adopts to the corresponding welding technology in order to reach the requirements of oil resistance.
To ensure the safe operation, the oil resistance strength should reach 21×106 pa, and can bear 10×106 pa impact force.
The oil resistance strength of domestic solenoid is 6.3×106 pa in general. It is much lower than Bosch solenoid, so it is always used in medium and low hydraulic system.
Service-life of solenoid
The service life of Bosch solenoid is much longer. Because of the reasonable structure, the perfect cooperation between the characteristic curve and the spring force, and the high-quality technology, the service-life of the DC solenoid and the AC solenoid can reach10x108 times. But the domestic solenoid cannot reach this standard. For the domestic solenoid, the DC wet-type solenoid can use 6×106 times, and the AC wet solenoid can use 10×106 times. As for dry-type solenoid, the gap is greater. The AC dry-type solenoid can use 10×105 times only.