Electric control high-pressure fuel injection device with high reliability

Abstract

The invention discloses an electric control high-pressure fuel injection device with high reliability and aims at providing a fuel injection device good in heat dissipation effect, more rapid in dynamic response and more accurate in fuel injection amount. According to the technical scheme, the angle of a valve seat opening cone angle A of a conical opening of a valve seat (12) is larger than that of a cone angle B of a valve rod truncated cone, and therefore annular gaps can be formed between a necking down part at the lower end of a cone of a valve rod (4) and a conical opening in the upper end portion of the valve seat (12) and between matched cylindrical faces. A cylinder platform shoulder for making a pressed part at the upper end of an iron core get away from the electromagnet main flux passing path is manufactured at the upper portion of the iron core (3), the upper end face of the iron core makes contact with the lower end face of an inner frame (1), an annular groove with a downward opening is formed in the lower end of the iron core, and a coil (5) wrapped by a coil frame (51) is assembled in the annular groove. A gap for expansion of the coil frame is reserved in the tops of the coil frame and the annular groove of the iron core.

Description

technical field [0001] The invention relates to an electronically controlled high-pressure fuel injection device mainly used in a high-pressure common rail fuel supply system. Electronically controlled high-pressure fuel injection device is commonly known as "electronically controlled fuel injector". Background technique [0002] The electronically controlled high-pressure common rail oil supply system is the most advanced diesel engine oil supply system today. Compared with all electronically controlled oil supply systems used in diesel engines in the past, such as electronically controlled unit pumps, electronically controlled pump nozzles, electronically controlled distribution pumps, etc., there are three main characteristics. One is that the injection pressure is decoupled from the engine speed, and the injection pressure has nothing to do with the engine speed, so the electronically controlled high-pressure common rail injection system can provide the best injection p...

AI Technical Summary

Problems solved by technology

[0010] like figure 2 The deficiency of the electromagnet assembly of the prior art shown in is that the lower end face of the iron core 3 is located on the inner cavity notch plane of the electromagnet housing 9, and the top of the iron core 3 is in contact with the inner skeleton 1, and through the electromagnet The upper end of the shell 9 is closed to press the iron core 3 tightly. As a result, the outer cylinder of the iron core 3 produces a large assembly stress, which seriously affects the magnetic permeability of the iron core 3, thereby greatly reducing the efficiency of the electromagnet.

[0011] like figure 2 The disadvantage of the prior art electromagnet assembly shown in is that, when the electromagnet is working, an eddy current will be generated inside the iron core, and the coil itself will also generate heat. If the heat cannot be dissipated in time, it will affect the electromagnet The reliability of the iron work has a great impact, and the electromagnet will be burned in severe cases. The iron core 3 of the prior art can only flow through the gap between the armature and the iron core to flow to the inner hole of the iron core to dissipate heat. The gap between the core 3 and the armature 6 is only 0.1mm, and the gap continues to shrink during the movement of the armature, resulting in a large flow resistance of the fuel. The outer cylindrical surface of the iron core 3 in the prior art has no fuel flow. However, the circulation area of ​​the inner hole of the iron core 3 is only 13% of the outer circle area, obviously only through the inner hole heat dissipation can not get a good heat dissipation effect, so it will have an impact on the reliability of the electromagnet

[0012] The third shortcoming of the electromagnet assembly of the prior art is that there is no reserved gap between the coil bobbin 51 and the top of the groove of the iron core 3. When the electromagnet is working, the coil and the bobbin will heat and expand, because there is no space for expansion at the upper end. space, the bottom surface of the coil frame can only move downward, and the geometric neutral plane of the coil and frame also moves downward. When the electromagnet stops working and cools down, the coil and frame will cool and shrink again. Shrinkage is no longer returning to the original position, but the two ends of the coil and the skeleton retract toward its geometric neutral plane at the same time. After the electromagnet undergoes long-term work and repeated thermal expansion and contraction, the coil skeleton will gradually move downward as a whole. , its lower end surface will also gradually move downward accordingly. Once the bottom surface of the coil bobbin is higher than the low plane of the iron core, it will affect the work of the electromagnet. What is more serious is that the coil and the bobbin will drag the wire, in severe cases, the wire will be torn off to make the electromagnet invalid

[0013] The fourth shortcoming of the electromagnet assembly of the prior art is that there is only one "O"-shaped sealing ring 52 between the inner frame 1 and the electromagnet housing 9, and the sealing ring is only 1 mm in diameter because of the sealed connecting rod, which belongs to The ultra-small diameter seal is prone to oil leakage when the pressure fluctuates greatly

[0014] The disadvantage of the above-mentioned control valve assembly in the prior art is that during the closing period of the sealing ball 16, the sealing ball 16 is always under the action of high-pressure fuel oil pressure, and the electromagnet spring needs a large spring force to press the sealing ball 16 to make it It is located on the conical surface of the valve seat 12, thus the electromagnet spring force must be increased. The electromagnet spring force is a closing force. After the electromagnet spring force is increased, if it is to be opened, the electromagnetic force on the armature 6 must also be required. As it increases, the driving power consumption is greatly increased

[0015] At the same time, a more prominent problem with the control valve assembly of the prior art is that the magnetic field force required to open the control valve due to the pressure of the high-pressure fuel oil before the sealing ball 16 is opened is relatively small. The force acting on the sealing ball 16 suddenly decreases a lot immediately, and the resultant force of opening the sealing ball decreases suddenly. If the control valve is to be continuously opened, the electromagnetic force must also be able to increase suddenly, but the increase speed of the magnetic flux density of the electromagnetic field cannot catch up with This requirement, so the increase of the electromagnetic force will not meet this requirement, causing the sealing ball 16 to close again. After closing, the hydraulic pressure on the sealing ball 16 will return to the maximum, so the control valve will be opened again. The vibration of the sealing ball 16 is prevented until the electromagnetic force is increased enough to be able to overcome the fluctuation of the high-pressure fuel fluid pressure, and then it can continue to open

The above situation also occurs during the closing process of the control valve, which affects the accuracy of the flow out of the control valve

[0016] The disadvantage of the control valve assembly in the prior art is that the moving parts of the control valve include five parts including a sealing ball, a sealing ball seat, a valve stem, an armature, and an opening gasket. Factors such as the difficulty in controlling the shape and position tolerance of the hole lead to high manufacturing costs

[0017] The disadvantage of the control valve assembly in the prior art is that the valve stem 4 with a solid structure increases the moving mass and affects the dynamic response of the control valve.

[0018] figure 2 The disadvantage of the prior art shown is that the high-pressure fuel is sealed between the electronically controlled fuel injector body 38 and the valve seat 12 using the radial sealing method of the sealing ring 20, and the material of the sealing ring 20 is plastic material, not only The strength is low, the sealing effect is poor, and there is also the problem of sealing deterioration

[0019] figure 2 The deficiency of the prior art shown is that, and because the skin thickness of the valve seat 12 is only about 2mm, it is easy to cause the deformation of the valve seat 12. If the interference of the sealing ring 20 is large, it is easy to cause the piston rod 42 to contact the valve seat. The cavities of 12 are stuck, if the interference of the sealing ring 20 is small, a reliable sealing effect cannot be achieved

Therefore, it is very difficult to control the size of the plastic sealing ring

[0020] figure 2 The disadvantage of the prior art shown is that in order to return the fuel leaked from the gap between the needle valve body 29 and the needle valve 30 to the low-pressure oil circuit, it is necessary to process the low-pressure oil return oblique hole on the electronically controlled injector body 38 39, and the low-pressure oil return inclined hole 39 is a long and thin hole, which is difficult to process

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