A coil current loading method for an electro-hydraulic servo valve

Abstract

The present application belongs to the field of electro-hydraulic servo, and relates to a coil current loading method of an electro-hydraulic servo valve. For the electro-hydraulic servo valve with two same coils, i.e. coil 1 and coil 2, the positive terminal of coil 1 is A, and the negative terminal is B; the positive terminal of coil 2 is C, and the negative terminal is D; the spool displacement of the electro-hydraulic servo valve is proportional to the sum of the current from A to B and the current from C to D, a constant current I0 from B to A is input when coil 1 is loaded, a variable current I from C to D opposite to the direction of coil 1 is input when coil 2 is loaded, and the current I is always not zero; the current input to the coil of the electro-hydraulic servo valve is always a value greater than the design value I min , and is not zero. When the input signal is zero or lower than a certain value, a fault can be reported, the coil current of the servo valve is displayed to be abnormal, when the coil of the servo valve loses power, a fault is reported immediately, the controller can start a safety program to terminate the operation of the hydraulic system, and the equipment maintenance personnel can immediately carry out inspection.

Description

Technical Field

[0001] The technical field of this invention is hydraulic control and hydraulic servo valves, and in particular, it relates to a coil current loading method for an electro-hydraulic servo valve. Background Technology

[0002] Electro-hydraulic servo valves are important control components in hydraulic servo systems. The valve spool displacement is proportional to the current input to the electro-hydraulic servo valve coil, and the output flow rate is generally proportional to the valve spool displacement. Its rated current is typically a symmetrical value; generally, when the input current is zero, the electro-hydraulic servo valve is in the zero position, the output flow rate is zero, and the valve spool is in the zero position.

[0003] Currently used single-coil loading, parallel loading, and series loading methods all result in zero input current corresponding to zero output of the electro-hydraulic servo valve. However, during displacement or pressure control, the electro-hydraulic servo valve is mostly in a zero position, with its input current being a very small value near zero. When a control system malfunctions, the control current input to the electro-hydraulic servo valve is also likely to be zero. Therefore, the control system cannot easily distinguish whether the electro-hydraulic servo valve is in normal operating condition. Summary of the Invention

[0004] The purpose of this invention:

[0005] This invention proposes a coil current loading method for an electro-hydraulic servo valve, which solves the problem in the prior art where, when the control system malfunctions, the control current input to the electro-hydraulic servo valve may also be zero, making it difficult for the control system to distinguish whether the electro-hydraulic servo valve is in normal working condition.

[0006] The technical solution of the present invention is as follows:

[0007] A method for loading the coil current of an electro-hydraulic servo valve is provided. For an electro-hydraulic servo valve with two identical coils, namely coil 1 and coil 2, the positive terminal of coil 1 is A and the negative terminal is B; the positive terminal of coil 2 is C and the negative terminal is D. The valve core displacement of the electro-hydraulic servo valve is proportional to the sum of the current flowing from A to B and the current flowing from C to D. When coil 1 is loaded, a constant current I0 flowing from B to A is input. When coil 2 is loaded, a variable current I flowing from C to D in the opposite direction to that of coil 1 is input. The current I is never zero.

[0008] Furthermore, the input current I0 of coil 1 is related to the rated current I of a single coil of the electro-hydraulic servo valve. e and the minimum input current I of coil 2 as specified in the design min The relationship is:

[0009] I0 = I min +I e .

[0010] Furthermore, I min >0.

[0011] Furthermore, the maximum value of the input current I of coil 2 is I max With the rated current I of the single coil of the electro-hydraulic servo valve e and the specified minimum input current I of coil 2 min The relationship is:

[0012] I max =I min +2I e .

[0013] Furthermore, when the electro-hydraulic servo valve is in the zero position, that is, when the valve core is in the neutral position, the magnitude of the current input to coil 2 is the same as that of coil 1, which is I0, but the direction of the current is opposite to that of coil 1.

[0014] Furthermore, the valve core displacement of the electro-hydraulic servo valve is proportional to the input current of coil 2.

[0015] Furthermore, the input current of coil 2 is I min At that time, the valve core of the electro-hydraulic servo valve outputs the maximum negative displacement.

[0016] Furthermore, the input current of coil 2 is I max At that time, the valve core of the electro-hydraulic servo valve outputs the maximum positive displacement.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention proposes a method for loading the coil current of an electro-hydraulic servo valve, wherein the current input to the coil of the electro-hydraulic servo valve is always greater than the design value I. min The input signal must be a non-zero value. If a fault warning module is added to the control system design, it can report a fault when the input signal is zero or below a certain value, displaying an abnormality in the servo valve coil current. When the servo valve coil loses power, the fault warning module can immediately report the fault, the controller can initiate a safety procedure to terminate the hydraulic system, and equipment maintenance personnel can then immediately conduct an inspection. This improves the system's testability and safety. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a dual-nozzle baffle electro-hydraulic servo valve with dual coils, according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of coil current loading according to an embodiment of the present invention;

[0021] Figure 3 This is a graph showing the valve core displacement of the electro-hydraulic servo valve as a function of the input current of coil 2.

[0022] Wherein: 1 is coil 1, 2 is coil 2, and 3 is valve core. Detailed Implementation

[0023] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. This description is not restrictive, and actual implementations are not limited thereto. If those skilled in the art, inspired by this description, design similar structures and embodiments without creative effort, they should all fall within the protection scope of the present invention.

[0024] Example 1:

[0025] This invention proposes a coil current loading method for an electro-hydraulic servo valve. For an electro-hydraulic servo valve with two identical coils, the positive terminal of coil 1 is designated as A, and the negative terminal as B; the positive terminal of coil 2 is designated as C, and the negative terminal as D. The valve core displacement of the electro-hydraulic servo valve is proportional to the sum of the current flowing from A to B and the current flowing from C to D. When coil 1 is loaded, a constant current I0 flowing from B to A is input. When coil 2 is loaded, a variable current I, flowing in the opposite direction to coil 1 from C to D, is input. Current I is never zero. The minimum input current of coil 2 is set to I. min Then the input current I0 of coil 1 is related to the rated current I of a single coil of the electro-hydraulic servo valve. e The relationship is:

[0026] I0 = I min +I e , where: I min >0

[0027] The maximum value of the input current I of coil 2 max With the rated current I of the single coil of the electro-hydraulic servo valve e and the specified minimum input current I of coil 2 min The relationship is:

[0028] I max =I min +2I e

[0029] When the electro-hydraulic servo valve is in the zero position, the current input to coil 2 is the same as that to coil 1, both being I0, but the current direction is opposite to that of coil 1. The valve core displacement of the electro-hydraulic servo valve is proportional to the input current of coil 2. Specifically, the input current of coil 2 is I... min At that time, the valve core of the electro-hydraulic servo valve outputs the maximum negative displacement; the input current of coil 2 is I. max At that time, the valve core of the electro-hydraulic servo valve outputs the maximum positive displacement.

[0030] The current input to the electro-hydraulic servo valve coil in this invention is always greater than the design value I. minThe input signal must be a non-zero value. If a fault warning module is added to the control system design, it can report a fault when the input signal is zero or below a certain value, displaying an abnormality in the servo valve coil current. When the servo valve coil loses power, the fault warning module can immediately report the fault, the controller can initiate a safety procedure to terminate the hydraulic system, and equipment maintenance personnel can then immediately conduct an inspection. This improves the system's testability and safety.

[0031] Another embodiment of the present invention will now be described with reference to the accompanying drawings.

[0032] Figure 1 This is a dual-nozzle baffle electro-hydraulic servo valve with dual coils, including coil 1, coil 2, and valve core 3. Its rated current is ±8mA, and the displacement of valve core 3 is ±0.5mm, proportional to the sum of the currents input to coils 1 and 2. When current flows in from A+ or C+ and out from B- or D-, the valve core produces a positive displacement; when current flows in from B- or D- and out from A+ or C+, the valve core produces a negative displacement. The minimum input current is set to 4mA when designing the controller. When using the electro-hydraulic servo valve, if a current of 12mA is input to coil 1 from B- to A+, then a current of 4-20mA is input to coil 2 from C+ to D-, which controls the valve core to move from a maximum negative displacement of -0.5mA to a maximum positive displacement of +0.5mA. 4mA corresponds to a valve core displacement of -0.5mA, 12mA corresponds to the valve core in the neutral position, and 20mA corresponds to a valve core displacement of +0.5mA. The output flow rate of an electro-hydraulic servo valve is directly proportional to the valve core displacement. Therefore, 4mA corresponds to the maximum negative flow rate of the electro-hydraulic servo valve, 12mA corresponds to the electro-hydraulic servo valve at zero position, and 20mA corresponds to the maximum positive flow rate of the electro-hydraulic servo valve. For example... Figure 3 As shown, in this example, X max =0.5mm, I min =4mA, I0=12mA, I max =20mA.

[0033] In the control system, a fault is reported when the coil current is less than 2mA. Therefore, when the controller malfunctions and the coil loses power, a fault is reported and the system operation is terminated.

[0034] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for loading coil current into an electro-hydraulic servo valve, characterized in that, For an electro-hydraulic servo valve with two identical coils, namely coil one and coil two, the positive terminal of coil one is A and the negative terminal is B; the positive terminal of coil two is C and the negative terminal is D; the valve core displacement of the electro-hydraulic servo valve is proportional to the sum of the current flowing from A to B and the current flowing from C to D. When coil one is loaded, a constant current flowing from B to A is input. When coil two is loaded, a variable current is input, flowing from C to D in the opposite direction to that of coil one. Current The input current of coil one is never zero. The rated current of a single coil in an electro-hydraulic servo valve and the minimum input current of coil two as specified in the design. The relationship is: Input current of coil two maximum value Rated current of a single coil in an electro-hydraulic servo valve and the specified minimum input current of coil two The relationship is: ; .

2. The coil current loading method for an electro-hydraulic servo valve according to claim 1, characterized in that, When the electro-hydraulic servo valve is in the zero position, i.e., the valve core is in the neutral position, the current input to coil two is the same as that to coil one, both being... The direction of the current is opposite to that of coil one.

3. The coil current loading method for an electro-hydraulic servo valve according to claim 1, characterized in that, The valve core displacement of the electro-hydraulic servo valve is proportional to the input current of coil two.

4. The coil current loading method for an electro-hydraulic servo valve according to claim 3, characterized in that, The input current of coil two is At that time, the valve core of the electro-hydraulic servo valve outputs the maximum negative displacement.

5. The coil current loading method for an electro-hydraulic servo valve according to claim 3, characterized in that, The input current of coil two is At that time, the valve core of the electro-hydraulic servo valve outputs the maximum positive displacement.

Images