A method for adjusting air gap to improve the stability of solenoid valve current characteristics

Abstract

A method for adjusting the air gap to improve the stability of the solenoid valve current characteristics, comprising: Step S1: Assemble the solenoid valve so that the lower surface of the armature is in contact with the surface of the valve body when the solenoid valve is in the closed state; Step S2: Apply a constant current Ia to the solenoid valve coil, and according to the solenoid valve parameters, obtain the pressure P generated by the valve core assembly on the throttle hole when the solenoid valve coil passes through the constant current Ia; Step S3: Apply a constant pressure P1 to the gas cavity at the bottom of the valve seat, and P1 is not greater than P; Step S4: Push the valve seat in the direction of expanding the air gap to cause displacement of the interference fit surface between the valve seat and the valve body, and at the same time detect the pressure of the gas in the gas cavity; Step S5: When the pressure loss of the gas in the gas cavity is detected, stop pushing the valve seat, and at this time the adjusted air gap value of the solenoid valve is Xp. It effectively avoids the deviation between the actual air gap value and the ideal air gap value caused by errors during the assembly process, and sets the ideal air gap after the solenoid valve is assembled.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle brake solenoid valve processing, and in particular to an air gap adjustment method for improving the stability of current characteristics of the solenoid valve. Background Art

[0002] With the development of automobile technology, people have put forward higher requirements for the power, economy, safety, operability and comfort of automobiles, and the mechanical system in the automobile is gradually changing to an electronic mechanical system. The existing automobile braking system gives different optimal braking forces to each wheel according to the friction between the tire and the road during the vehicle's driving process, and uses the switch of the solenoid valve to adjust the automobile braking pressure to achieve the stability of controlling the vehicle's driving. The closing response speed of the solenoid valve and the sealing reliability after closing depend to a great extent on the size of the electromagnetic force. In particular, the solenoid valve using a linear control strategy has very high requirements for the consistency of the electromagnetic force.

[0003] The existing technical solution reduces the range of current fluctuation under a certain solenoid valve pressure difference by setting the manufacturing tolerance of the air gap within a certain range. However, the main factors affecting the current stability of the solenoid valve under a certain pressure difference are not only the air gap, but also the valve seat angle and the spring. In addition, during the solenoid valve processing, the solenoid valve parts processing size deviation will also have a certain impact. The combination of various factors makes the solenoid valve product maintain a large current fluctuation range under a certain typical pressure difference, and the typical output characteristic current-pressure difference characteristic of the finished solenoid valve has a large discreteness, which leads to the problem of unstable control of the wheel load pressure by the solenoid valve. Summary of the invention

[0004] The present invention aims to solve the problem that the finished product of automobile brake solenoid valve in the prior art has a large fluctuation range of solenoid valve maintaining current due to manufacturing tolerance and air gap deviation caused by processing and assembly and part size, and provides an air gap adjustment method for improving the stability of solenoid valve current characteristics by directly setting the solenoid valve maintaining current value under typical pressure difference.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for adjusting the air gap for improving the stability of the current characteristic of a solenoid valve, the solenoid valve comprising a valve body and a valve seat arranged inside the valve body, an interference fit between the valve shell of the valve seat and the valve body, the bottom of the valve seat being connected to a gas volume through a throttle hole, a valve core assembly being arranged above the valve seat; and an air gap, a moving iron being arranged on the upper surface of the valve core assembly, the lower surface of the moving iron covering the upper surface of the valve body, the air gap being the distance between the lower surface of the moving iron and the upper surface of the valve body, the method comprising the following steps:

[0007] Step S1: Assemble the solenoid valve so that the lower surface of the moving iron fits the upper surface of the valve body when the solenoid valve is in a closed state;

[0008] Step S2: applying a constant current Ia to the solenoid valve coil, and obtaining, according to the solenoid valve parameters, a pressure P generated by the valve core assembly on the throttle hole when the constant current Ia passes through the solenoid valve coil and the lower surface of the moving iron is in a state of being in contact with the upper surface of the valve body, i.e., in a state of zero air gap;

[0009] Step S3: applying a constant pressure P1 to the gas chamber at the bottom of the valve seat, and P1 is not greater than P;

[0010] Step S4: pushing the valve seat in the direction of expanding the air gap so as to displace the interference fit surface between the valve seat and the valve body, and detecting the pressure of the gas in the gas chamber at the same time;

[0011] Step S5: When it is detected that the gas pressure in the gas chamber is depressurized, stop pushing the valve seat, and the adjusted air gap value of the solenoid valve is Xp. The electromagnetic coil generates a downward electromagnetic force under the action of the constant current Ia, and the pressure P generated by the valve core assembly on the throttle hole is greater than the constant pressure P1 applied to the gas chamber at the bottom of the valve seat. At this time, the throttle hole is in a sealed state; it is known that under the action of the constant current, the electromagnetic force decreases as the air gap increases. When the valve seat is pushed, the air gap gradually increases and the electromagnetic force gradually decreases. When the air gap gradually increases to the point where the electromagnetic force provided by the moving iron cannot maintain the sealing state of the throttle hole, the gas in the gas chamber leaks from the throttle hole, resulting in a depressurization in the gas chamber. At this time, stop pushing the valve seat. At this time, the air gap value of the solenoid valve is the adjusted air gap value, and the current pressure difference of the solenoid valve under this air gap value is more stable; effectively avoid errors in the assembly process that cause deviations between the actual air gap value and the ideal air gap value, find the ideal air gap after the solenoid valve is assembled, ensure the product quality of the solenoid valve, and improve the stability and control accuracy of the solenoid valve product.

[0012] Preferably, the method includes: when the pressure loss of the gas in the gas chamber is detected in step S5, the valve seat is stopped from being pushed; specifically, when the difference Δp between the pressure value P' and the pressure P1 of the gas chamber is detected to be 0.25 bar to 0.5 bar, the valve seat is stopped from being pushed. The electromagnetic force on the valve core assembly cannot maintain the sealing state of the throttle hole, and the gas in the gas chamber is lost from the throttle hole, resulting in a loss of pressure in the gas chamber.

[0013] Preferably, the pressure P is positively correlated with the electromagnetic force generated by energizing the electromagnetic coil, negatively correlated with the spring force, and negatively correlated with the contact area between the throttle hole and the valve core assembly.

[0014] Preferably, the greater the difference between P and P1, that is, the smaller P1 is, the greater the air gap value Xp after the solenoid valve is adjusted; the smaller the difference between P and P1, that is, the greater P1 is, the smaller the air gap value Xp after the solenoid valve is adjusted. Under the action of a constant current, the electromagnetic force decreases as the air gap increases. When the valve seat is pushed, the air gap gradually increases and the electromagnetic force gradually decreases.

[0015] Preferably, a servo electric cylinder unit is further included, and the servo electric cylinder unit is used to drag the valve seat to move towards the valve core assembly.

[0016] Preferably, it further comprises a pressure sensing unit, wherein the pressure sensing unit is arranged in the gas containing cavity and is used for detecting the pressure of the gas in the gas containing cavity.

[0017] Therefore, the present invention has the following beneficial effects: finding the ideal air gap after the solenoid valve is assembled, effectively avoiding errors during the assembly process that lead to deviations between the actual air gap value and the ideal air gap value, ensuring the product quality of the solenoid valve, and improving the current-pressure difference characteristics and control accuracy of the solenoid valve product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The invention is a cross-sectional view of a solenoid valve according to a method for improving the stability of the current characteristics of a vehicle brake solenoid valve according to an embodiment of the present invention.

[0019] Figure 2 The typical output characteristic curve of a solenoid valve of a method for improving the stability of a current characteristic of a vehicle brake solenoid valve according to an embodiment of the present invention.

[0020] In the figure: 1, valve body 2, valve seat 3, throttle hole 4, gas chamber 5, valve core assembly 6, moving iron 7, air gap 8, valve core push rod 9, ball groove 10, valve ball 11, spring. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0022] Example:

[0023] An air gap adjustment method for improving the stability of the current characteristics of the solenoid valve, such as Figure 1As shown, the solenoid valve includes a valve body 1 and a valve seat 2 arranged on the inner side of the valve body 1, the valve seat 2 and the valve body 1 are interference fit, the bottom of the valve seat 2 is connected to the gas chamber 4 through a throttle hole 3, and a valve core assembly 5 is provided above the valve seat 2; it also includes an air gap 7, a moving iron 6 is provided on the upper surface of the valve core assembly 5, and the lower surface of the moving iron 6 covers the upper surface of the valve housing, and the air gap 7 is the distance between the lower surface of the moving iron 6 and the upper surface of the valve body 1. The valve core assembly 5 includes a valve core push rod 8, a spring 11 sleeved on the outside of the valve core push rod 8, and a valve ball 10 arranged at the lower part of the valve core push rod 8. The lower surface of the valve core push rod 8 is provided with a ball groove 9, and the valve ball 10 is arranged in the ball groove 9. The depth of the ball groove 9 is not greater than the diameter of the valve ball 10; in the closed state, the lower surface of the valve ball 10 fits with the throttling hole 3, and the diameter of the valve ball 10 is greater than the diameter of the throttling hole 3 shown. Before setting the air gap, that is, in the zero air gap state, the upper surface of the valve core push rod 8 is flush with the upper surface of the valve body 1.

[0024] A servo electric cylinder unit is provided at the bottom of the valve seat 2, and the servo electric cylinder unit is used to push the valve seat 2 to move toward the valve core assembly 5. A pressure sensor is provided in the gas chamber 4, and the pressure sensor is used to detect the pressure of the gas in the gas container chamber. The specific adjustment steps are as follows:

[0025] Step S1: Assemble the solenoid valve so that the lower surface of the upper valve seat 2 fits with the upper surface of the valve housing when the solenoid valve is in a closed state;

[0026] Step S2: applying a constant current Ia=0.9A to the solenoid valve coil, and obtaining, based on the solenoid valve parameters, a pressure P generated by the valve core assembly 5 on the throttle hole 3 when the constant current Ia passes through the solenoid valve coil and the lower surface of the moving iron and the upper surface of the valve body are in a state of contact with each other, i.e., in a state of zero air gap;

[0027] Step S3: applying a constant pressure P1=100 bar to the gas chamber 4 at the bottom of the valve seat 2, and P1 is not greater than P;

[0028] Step S4: pushing the valve seat 2 in the direction of expanding the air gap 7 so that the surfaces of the valve shell of the valve seat 2 and the fixed seat that match each other are displaced, and at the same time detecting the pressure of the gas in the gas chamber 4;

[0029] Step S5: When it is detected that the difference Δp between the pressure value P' of the gas chamber 4 and the pressure P1 satisfies 0.25 bar to 0.5 bar, the valve seat 2 is stopped from being pushed. At this time, the air gap 7 value after the solenoid valve is adjusted is Xp. The pressure P generated by the valve core assembly 5 on the throttle hole 3 is greater than the constant pressure P1 applied to the gas chamber 4 at the bottom of the valve seat 2. At this time, the throttle hole 3 is in a sealed state; Figure 2It is known that under the action of constant current Ia, the relationship curve between the electromagnetic force Fp exerted on the moving iron 6 and the size of the air gap 7; therefore, when the pressure required for the electromagnetic valve to be sealed is P1, the required electromagnetic force is Fp, and the size of the air gap 7 is Xp. The larger the difference between P and P1, that is, the smaller P1, the larger the value Xp of the air gap 7 after the electromagnetic valve is adjusted; the smaller the difference between P and P1, that is, the larger P1, the smaller the value Xp of the air gap 7 after the electromagnetic valve is adjusted. During implementation, the P1 value can be selected based on empirical values ​​and the basic structure of the electromagnetic valve. Therefore, it is necessary to adjust the air gap 7 of the moving iron 6 of the solenoid valve. The electromagnetic force exerted on the moving iron 6 decreases as the air gap 7 increases. When the valve seat 2 is pushed, the air gap 7 gradually increases and the electromagnetic force gradually decreases. When the air gap 7 gradually increases, the electromagnetic force provided by the moving iron 6 cannot maintain the sealing state of the throttle hole 3, and the gas in the gas chamber 4 leaks out from the throttle hole 3, resulting in pressure loss in the gas chamber 4. At this time, the valve seat 2 is stopped from being pushed. At this time, the air gap 7 value of the solenoid valve is the adjusted air gap 7 value, namely Xp. The current-pressure difference characteristic of the solenoid valve at this air gap 7 value is more stable. It can effectively avoid errors in the assembly process that cause deviations between the actual air gap 7 value and the ideal air gap 7 value. After the solenoid valve is assembled, the ideal air gap 7 is found to ensure the product quality of the solenoid valve and improve the stability and precision of the solenoid valve product.

[0030] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0031] Although the terms such as electromagnetic valve, electromagnetic coil, air gap, gas chamber, valve seat, etc. are frequently used in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. An air gap adjustment method for improving the stability of the solenoid valve current characteristics, characterized in that, the solenoid valve includes a valve body and a valve seat arranged inside the valve body. The valve seat and the valve body are in interference fit. The bottom of the valve seat is connected to a gas cavity through a throttle hole. Above the valve seat, there is a spool assembly. The spool assembly includes a spool push rod, a spring sleeved outside the spool push rod, and a valve ball arranged at the lower part of the spool push rod. There is also an air gap. The upper surface of the spool assembly is provided with a moving iron, and the lower surface of the moving iron covers the upper surface of the valve body. The air gap is the distance between the lower surface of the moving iron and the upper surface of the valve body. The method includes the following steps: Step S1: Assemble the solenoid valve so that the lower surface of the moving iron fits against the upper surface of the valve body when the solenoid valve is in the closed state; Step S2: Apply a constant current Ia to the solenoid valve coil. According to the solenoid valve parameters, obtain the pressure P generated by the spool assembly on the throttle hole in the state where the lower surface of the moving iron fits against the upper surface of the valve body, that is, the zero air gap state, when the solenoid valve coil passes through the constant current Ia; Step S3: Apply a constant pressure P1 to the gas cavity at the bottom of the valve seat, and P1 is not greater than P; Step S4: Push the valve seat in the direction of expanding the air gap to cause a displacement of the interference fit surface between the valve seat and the valve body, and at the same time detect the pressure of the gas in the gas cavity; Step S5: When the pressure loss of the gas in the gas cavity is detected, stop pushing the valve seat. At this time, the adjusted air gap value of the solenoid valve is Xp.

2. An air gap adjustment method for improving the stability of the solenoid valve current characteristics according to claim 1, characterized by, including: when the pressure loss of the gas in the gas cavity is detected in step S5, stop pushing the valve seat; specifically, when the difference Δp between the pressure value P' of the gas cavity and the pressure P1 satisfies 0.25 bar to 0.5 bar, stop pushing the valve seat.

3. An air gap adjustment method for improving the stability of the solenoid valve current characteristics according to claim 1 or 2, characterized by, the pressure P is positively correlated with the electromagnetic force generated by the energization of the solenoid valve coil, negatively correlated with the spring force, and negatively correlated with the contact area between the throttle hole and the spool assembly.

4. An air gap adjustment method for improving the stability of the solenoid valve current characteristics according to claim 3, characterized by, the greater the difference between P and P1, that is, the smaller P1, the greater the adjusted air gap value Xp of the solenoid valve; the smaller the difference between P and P1, that is, the greater P1, the smaller the adjusted air gap value Xp of the solenoid valve.

5. An air gap adjustment method for improving the stability of the solenoid valve current characteristics according to claim 4, characterized by, further including a servo electric cylinder unit, and the servo electric cylinder unit is used to drag the valve seat to move towards the spool assembly.

6. An air gap adjustment method for improving the stability of the solenoid valve current characteristics according to claim 5, characterized by, further including a pressure sensing unit, and the pressure sensing unit is arranged in the gas cavity to detect the pressure of the gas in the gas cavity.

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