Proportional valve failure causes and solutions

(1) Proportional electromagnet failure (1) The proportional electromagnet can not work (can not pass current) due to aging of plug socket [base], poor contact and desoldering of electromagnet. Meter testing can be used at this time, found infinite resistance, you can re-weld the wire, repair the socket and plug the socket. ② line 圑 component failure coil aging, burning wire,, the coil inside the coil and the coil temperature rise is too large and so on. Coil temperature rise caused by the proportion of the electromagnet output force is not enough, the rest will make the proportion of the electromagnet can not work. For the coil temperature is too large, can check the current is too large, the coil is enameled wire insulation is poor, the spool is stuck due to dirt, one by one to identify the cause and eliminate it; for the break, burn out and so on, Need to change the line 圑. ③ the main component of the armature assembly 衔 mainly armature because of its composition with the magnetic sleeve wear in the course of use, resulting in increased valve hysteresis. There are push rod guide armature and different heart, will also lead to increased hysteresis of force, we must rule out. ④ due to the welding is not strong, or use in the proportional valve pulse pressure under the action of the magnetic sleeve welding rupture, the proportion of electromagnet loss of function. ⑤ guide sleeve deformation under impact pressure, and the magnetic sleeve and the armature friction pair wear in the course of use, resulting in proportional valve hysteresis increases the phenomenon of hysteresis. ⑥ proportional amplifier so 嗥, resulting in the proportion of electromagnet does not work. At this point should check the various components of the amplifier circuit, eliminating the amplifier circuit failure. ⑦ The connection between the proportional amplifier and the electromagnet is broken or the terminal of the amplifier is disconnected, so that the proportional electromagnet does not work. At this point should be replaced broken, re-connect firmly. (2) Proportional pressure valve failure analysis and exclusion As the proportional pressure valve is only on the basis of an ordinary pressure valve, the pressure regulator handle into proportional solenoid only. Therefore, the common pressure valve produces a variety of faults, it will also produce a common pressure valve failure causes and exclusion method is also fully applicable to the corresponding proportional pressure valve (such as the overflow purdah proportional relief valve), can refer to the processing . In addition there are: ① proportional solenoid no current through, so that the pressure regulator failure at this time according to the "(1) proportional solenoid fault" content analysis. Occurred when the regulator fails, you can first check the current value of the meter to determine whether the solenoid control circuit problems, or the proportion of electromagnets have problems, or some problems, can symptomatic treatment. ② Although the current flowing through the proportional solenoid is rated, the pressure does not go up at all, or the required pressure is not proportional to the proportional relief valve shown in Figure 3-45. When the proportional pilot pressure regulator 1 ( Relief valve) and the main overflow between Fujian 5, still retains the common pilot overflow case solenoid; 4 a safety cabinet; 5 - the main relief Min valve pilot hand pressure regulating valve 4, where The role of safety valve. When the valve 4 is too low to adjust the pressure, although the passage of the proportional solenoid 3 is rated, the pressure does not go up. If the set pressure of the valve 4 is too low, the pilot flow back to the tank from the valve 4, so that the pressure does not come. At this point the valve 4 should be set pressure than the maximum working pressure of 1Mpa Fujian raised about. ③ the current flowing through the proportional solenoid has been too large, 伹 the pressure or go up, or can not get the required pressure at this time can check the proportional solenoid coil resistance, if far less than the specified value, then the interior of the solenoid coil Open circuit; if the electromagnet coil resistance is normal, then it is connected to the short circuit of the proportional amplifier. At this point should be replaced by the proportion of electromagnet, the connection is connected, or rewound coil installed. ④ When the pressure step changes, the small amplitude of the pressure fluctuations, the pressure instability is mainly due to the proportion of the iron core and the guide part (guide sleeve) between the dirt adhesion, impeding the movement of the core. In addition, the sliding part of the main valve sticky dirt, hinder the movement of the main Min core. Due to the influence of these contaminants, the hysteresis increases. In the hysteresis range, the pressure is not stable, the pressure fluctuations. Another reason is the iron core and the guide sleeve wear Vice, the gap increases, there will be pressure (by a certain current value) instability phenomenon. At this point, the valve and the proportional solenoid can be disassembled for cleaning, and the degree of contamination of the hydraulic oil can be checked. If more than the provisions of the oil should be changed; for iron core wear caused by the gap is too large, resulting in increased hysteresis loop, resulting in unstable voltage regulator, should increase the size of the core diameter to maintain a good fit with the guide sleeve. ⑤ pressure response delay, the pressure changes slowly due to the proportion of the electromagnet air is not put clean; set on the magnet core damping fixed orifice and the main orifice (or bypass orifice ) Is blocked by dirt and the movement of the proportional solenoid core and the main spool is unnecessarily obstructed. In addition, air enters the system, which usually occurs when the equipment is installed and starts running, or after long-term shutdown The occasion The solution is proportional pressure valve in the beginning just before use to loosen the deflation screw, put the clean air, there is oil outflow date. For dirt clogging the orifice and other circumstances to open the proportion of the solenoid valve and the main valve for cleaning, and in the air easy to concentrate the highest position of the system oil, it is best to set the deflation valve deflation or loose tube fittings deflated. ⑥ CGE electro-hydraulic proportional relief valve two faults a. When the coil input rated current (50mA), the inlet pressure less than the rated working pressure (21Mpa), but lower than the rated pressure of 2 ~ 6MPa. The reasons are as follows: after long-term use, the magnetic gap (air gap) in the magnetic circuit increases greatly due to the loosening of the fastening screw of the air gap adjusting spacer, iN / Rm) 2S where k-constant; i-coil input current; N-coil turns; Rm-reluctance; S- magnetic cross-sectional area. It can be seen that as long as the magnetic gap is slightly increased, the reluctance Rm is significantly increased, and the electromagnetic force 7 is decreased in a square relationship. The hydraulic pressure increases and the pressure in the upstream of the nozzle decreases. As a result, the pressure in the cavity of the main valve decreases and the pressure in this lower pressure increases with the weak spring in the upper chamber of the main valve, which reduces the pressure at which the main valve opens. That is, the inlet pressure Decline, but can not reach the maximum pressure (21Mpa). Solution: Appropriate increase or decrease the thickness of the gap adjustment shims, tighten the gap adjustment shims fastening screws, reducing the magnetic gap, the inlet pressure can be increased. The initial setting of the magnetic gap should be 0.89 ~ 0.94mm. b. The coil input current is zero, the initial valve pressure is too high (4 ~ 7Mpa). Normal, the initial pressure should be around. The minimum set pressure mainly depends on the initial clearance of nozzle baffle 0.1 ~ 0.13mm, too small, the initial pressure is too high. (3) Proportional flow valve failure analysis and troubleshooting ① flow can not be adjusted, throttling regulatory failure failure causes and solutions In addition to speed control valve failure analysis and troubleshooting, there are the following two points. a. Proportional solenoid failed to energize. The reasons are as follows: Proportional solenoid socket aging, poor contact; electromagnet lead wire desoldering; coil internal disconnection, etc., can refer to the above "(1) proportional solenoid fault" method of troubleshooting. b. Amplifier error. With the above part (2) ①, ⑤, ⑥. ② adjust the flow rate is not stable proportional flow valve flow control by changing the proportion of people through the solenoid current to achieve. When the input current value unchanged, the adjusted flow should not change. However, in fact, adjusting the flow rate (when inputting the same signal value), some changes often occur in the working process, which is due to the increase of hysteresis loop. Hysteresis refers to when the same signal (current) value input, due to the different input directions (positive and negative directions), after the same current signal value, causing the maximum output flow rate (or pressure) changes. Influencing factors of hysteresis are mainly due to the existence of radial imbalance force and mechanical friction. Then reduce the radial unevenness and reduce the friction factor and other measures to reduce the impact of mechanical friction on the hysteresis. Hysteresis is reduced, the good changes in the flow of natural changes smaller. Specific measures can be taken as follows. a. Minimize the wear of armature and sleeve. b. Push rod guide and armature should be concentric. c. pay attention to oil clean to prevent dirt from entering the gap between the armature and the magnetically permeable sleeve and stuck armature so that the armature with the input current value in proportion to move evenly, does not produce sudden jump phenomenon. Once the phenomenon of sudden jump, proportional flow valve output flow will follow the sudden jump so that the flow is not stable. d. Magnetic sleeve armature wear, pay attention to repair, so that the gap between the two remain in the appropriate range. These measures are quite beneficial and effective in maintaining the stability of the flow adjusted by the proportional flow valve. In addition, the general proportion of electromagnet driveControl Valve, Flow Control Valve, Hydraulic Control Valve, Proportional Directional Control Valve