CN202091298U - Bulk flow and high frequency response electrohydraulic vibrating device based on parallel connection of servo valves - Google Patents

Abstract

The utility model discloses a large-flow high-frequency-response electro-hydraulic vibration device based on the parallel connection of servo valves. The electro-hydraulic vibration device has more than two servo valves, the oil inlet of each servo valve is connected with the oil source, the oil return port of each servo valve is connected with the oil return tank, and the first working oil port of each servo valve is connected with the oil source. The first oil port of the double-rod symmetrical hydraulic cylinder is connected, and the second working oil port of each servo valve is connected with the second oil port of the double-rod symmetrical hydraulic cylinder; the displacement sensor is connected to the piston of the double-rod symmetrical hydraulic cylinder. The rod is connected; the displacement sensor and each servo valve are electrically connected with the controller. The electro-hydraulic vibration device of the utility model can meet the requirements of large flow rate and high frequency response of the electro-hydraulic vibration device, and realize the synchronous movement of the valve core when the servo valves are connected in parallel.

Description

Large-flow high-response electro-hydraulic vibration device based on servo valve parallel connection

technical field

The utility model belongs to the field of fluid transmission and control, and relates to an electro-hydraulic servo vibrating device, which is suitable for occasions where a hydraulic oil cylinder is used to drive a load to perform sinusoidal or periodic motion in a hydraulic system.

Background technique

In hydraulic vibration devices such as hydraulic vibration tables and linear friction welding machines, the position and speed of the hydraulic cylinder are required to reciprocate according to a sinusoidal curve of a certain frequency. Generally, the above functions are realized by an electro-hydraulic servo control system driven by a servo valve to a hydraulic cylinder. The opening of the servo valve changes sinusoidally according to the command signal of the control system, and the speed and position of the hydraulic cylinder will also move sinusoidally according to the same frequency. The zero position and amplitude of hydraulic cylinder movement can be controlled by adjusting the DC bias and amplitude of the command signal. As the equipment's requirements for the amplitude and frequency of the vibrating device continue to increase, the demand for the flow rate and frequency response of the servo valve also rises accordingly. In order to meet this demand, traditional electro-hydraulic vibration devices have the following structural forms:

One is to still use a single servo valve to drive the hydraulic cylinder, and try to improve the flow rate and frequency response of the servo valve, such as increasing the number of pilot stages, or using parallel pilot stages, or adopting new technologies and designs to improve electromechanical converters. frequency response. But its disadvantage is that, on the one hand, due to the limitations of various conditions, the effect of the above method is limited. With the increase of the rated flow rate of a single servo valve, its frequency response will be greatly reduced, and it is difficult to achieve large flow and high frequency response. On the other hand, even if there are servo valve products that meet the requirements of large flow and high response, their prices are generally unacceptably high.

The second is to use multiple hydraulic cylinders in parallel to drive the load. In this way, the required flow rate of a single oil cylinder and its servo valve can be unchanged or increased slightly, and the servo valve only needs to meet the high-frequency response requirements, and the parallel connection of multiple cylinders can significantly increase its driving force. However, this method also has many disadvantages, such as the need to configure multiple sets of cylinders and servo valves, the parallel connection of multiple cylinders involves complex decoupling control problems, complex structure, and in some cases, it is not allowed to use multiple actuators due to the limitation of installation space. Parallel structure.

Utility model content

The purpose of the utility model is to overcome the deficiencies in the existing electro-hydraulic vibrating device, and provide a large flow and high-response electro-hydraulic vibrating device based on the parallel connection of servo valves with simple structure.

In order to achieve the above purpose, the technical means adopted by the utility model are: its large-flow high-frequency electro-hydraulic vibration device based on servo valve parallel connection includes oil source, oil return tank, more than two servo valves, double-rod symmetrical hydraulic cylinders, Controller and displacement sensor; the oil inlet of each servo valve is connected with the oil source, the oil return port of each servo valve is connected with the oil return tank, and the first working oil port of each servo valve is connected with the double outlet rod The first oil port of the symmetrical hydraulic cylinder is connected, and the second working oil port of each servo valve is connected with the second oil port of the double-rod symmetrical hydraulic cylinder; the displacement sensor is connected with the piston rod of the double-rod symmetrical hydraulic cylinder. connected; the displacement sensor and each servo valve are electrically connected to the controller.

Further, there are two servo valves in the utility model.

Further, the utility model also includes an acceleration sensor, which is connected to the piston rod of the double-rod symmetrical hydraulic cylinder.

Further, the utility model also includes a first pressure sensor and a second pressure sensor, the first pressure sensor is connected to the first oil port of the double-rod symmetrical hydraulic cylinder, and the second pressure sensor is symmetrical to the double-rod The second oil port of the hydraulic cylinder is connected.

Compared with the prior art, the utility model has the advantages of:

(1) Using multiple servo valves in parallel to drive the same oil cylinder, the flow required by the device is provided by multiple valves connected in parallel at the same time, and there is little requirement for the flow of each servo valve. The servo valve with medium flow rate and high frequency response common in the market can be selected, which is easy to implement and saves costs, and at the same time meets the high requirements of large flow rate, high frequency response, high performance and price ratio.

(2) Only one hydraulic cylinder is used to drive the load, which has a simple structure and saves installation space.

(3) By adopting the electro-hydraulic vibration device of the present utility model, the parallel servo valves can be controlled synchronously, realizing the synchronization when the spool moves through the zero position, and the control accuracy is high, which effectively solves the problem of the valve between the parallel servo valves. Problems such as flow reduction and commutation shock caused by the problem of asynchronous core movement.

(4) The electro-hydraulic vibration device of the utility model has no limitation on the diameter and the number of parallel servo valves, and the number and size of the required parallel servo valves can be reasonably configured according to the flow requirements of the device, which is flexible and convenient.

Description of drawings

Fig. 1 is the hydraulic principle diagram of an embodiment of the electro-hydraulic vibrating device of the present invention;

Fig. 2 is under the input signal of 50Hz, ± 20% of the full stroke, the parallel servo valve spool displacement curve after the synchronous control method is carried out to the electro-hydraulic vibration device of the utility model;

Fig. 3 is a partial enlarged view of Fig. 2 when the displacement of the spool of the parallel servo valve is crossing the zero position;

Fig. 4 is a partial enlarged view of Fig. 2 when the spool displacement of the parallel servo valve crosses the zero position negatively.

Detailed ways

As shown in Figure 1, the utility model is based on the parallel connection of servo valves with large flow and high-response electro-hydraulic vibration device, including oil source 1, oil return tank 2, more than two servo valves, double-rod symmetrical hydraulic cylinder 5, controller 11 and Displacement sensor 7; the oil inlet port of each servo valve is connected with the oil source 1, the oil return port of each servo valve is connected with the oil return tank 2, and the first working oil port of each servo valve is connected with the double outlet rod symmetrical hydraulic pressure The first oil port of the cylinder 5 is connected, and the second working oil port of each servo valve is connected with the second oil port of the double-rod symmetrical hydraulic cylinder 5; the displacement sensor 7 is connected with the piston rod of the double-rod symmetrical hydraulic cylinder 5 Connection; the displacement sensor 7 and each servo valve are electrically connected with the controller 11. Wherein, the controller 11 can use a DSP chip from Texas Instruments, the specific model is TMS320F240.

If the piston rod of the double-rod symmetrical hydraulic cylinder 5 is also connected with an acceleration sensor 8, the acceleration signal of the piston rod motion can be measured, and the speed of the piston rod motion can also be calculated by integration, which can be collected by the controller 11 in the electro-hydraulic vibration device. These signals form the acceleration and speed feedback, together with the feedback signal of the displacement sensor 7, the three-parameter closed-loop vibration control of the piston rod is realized.

In addition, if the first oil port of the double-rod symmetrical hydraulic cylinder 5 is connected to the first pressure sensor 9, and the second oil port of the double-rod symmetrical hydraulic cylinder 5 is connected to the second pressure sensor 10, the double-rod symmetrical hydraulic cylinder 5 can be monitored in real time. If the pressure of the two working oil ports of the symmetrical hydraulic cylinder 5 exceeds the safe range, the controller 11 can send an alarm and take some corresponding safety measures.

It can be seen from the above that in the utility model, each servo valve adopts a parallel structure and works simultaneously during the vibration process of the electro-hydraulic vibration device. The diameter and quantity of the servo valve can be changed, increased or decreased depending on the actual performance requirements of the electro-hydraulic vibration device.

The controller 11 has multiple channels of DA (digital to analog) output and AD (analog to digital) input, each DA channel outputs an independent command signal to each corresponding servo valve, and at the same time through the AD channel The spool position feedback signal of the servo valve is collected. In addition, the controller 11 collects the signal of the displacement sensor 7 through the AD channel.

When the electro-hydraulic vibration device of the utility model is working, the operator sets parameters such as the target vibration frequency, amplitude, load mass and oil supply pressure of the oil source 1, and the controller 11 calculates the frequency of the spool movement of each servo valve accordingly. and initial magnitude. During the vibration process, the controller 11 will continue to detect the signal of the displacement sensor 7 to obtain the actual amplitude of the double-rod symmetrical hydraulic cylinder 5, and compare it with the set target amplitude. If the deviation between the two exceeds the allowable range, the front The calculated initial amplitude is corrected. According to the calculated frequency and initial amplitude, the controller 11 outputs command signals to drive each servo valve. Then, through the internal synchronous control of the controller 11, the amplitude and phase of the command signal output to each servo valve are adjusted, so as to finally achieve the synchronous movement among the parallel servo valves. At this time, the vibration amplitude generated by the double-rod symmetrical hydraulic cylinder 5 driven by each servo valve reaches the maximum, that is, the vibration device generates vibration with sufficient frequency and amplitude.

During the working process, the oil source 1 composed of a hydraulic pump and an accumulator is responsible for providing hydraulic oil with stable pressure and sufficient flow to the device, and the oil return tank 2 provides a smooth oil return path with low back pressure. Each servo valve is controlled by the instruction signal of the controller 11, and the opening of the valve core performs periodic reciprocating motion. The hydraulic oil passes through the openings of the servo valves and intermittently flows to the two working oil ports of the double-rod symmetrical hydraulic cylinder 5 at the set frequency, driving the piston rod of the double-rod symmetrical hydraulic cylinder 5 to perform periodic reciprocating motions, and the piston rod Drive the load to vibrate. The displacement sensor 7 and the acceleration sensor 8 measure the displacement and acceleration of the piston rod, and the first pressure sensor 8 and the second pressure sensor 9 measure the pressure of the two working oil ports of the double-rod symmetrical hydraulic cylinder 5 . The controller 11 collects the spool position feedback signals of each servo valve to realize synchronous control of each servo valve. The controller 11 also collects the above displacement, acceleration and pressure signals respectively to form a closed-loop control of the vibration device.

In the electro-hydraulic device of the utility model, a common and common servo valve whose frequency response meets the requirements is selected, and a plurality of parallel drives the same hydraulic oil cylinder to achieve the required large flow. Since the selected servo valve does not have high requirements on the flow rate, it is a common product in the market and the price is relatively reasonable. Therefore, multiple parallel connections can simultaneously meet the requirements of large flow rate, high frequency response, and high cost performance.

Taking two servo valves connected in parallel and the electro-hydraulic vibration device doing sinusoidal vibration as an example, the method for synchronously controlling the parallel servo valves of the electro-hydraulic vibration device of the present invention is explained in detail:

(1) Calculate the frequency and initial amplitude of the command signals of the first servo valve 3 and the second servo valve 4 respectively according to the target vibration frequency, amplitude, load and oil supply pressure of the vibration device.

Since the electro-hydraulic vibration device is vibrated by the double-rod symmetrical hydraulic cylinder 5, and the double-rod symmetrical hydraulic cylinder 5 is driven by the first servo valve 3 and the second servo valve 4, therefore, the vibration frequencies of the two are equal, that is, The frequencies of the command signals of the first servo valve 3 and the second servo valve 4 are both equal to the target vibration frequency. According to the cylinder diameter, rod diameter, standard vibration frequency and amplitude of the double-rod symmetrical hydraulic cylinder 5, the maximum flow rate required by the device can be directly calculated, and then according to the rated flow rate and oil source of the first servo valve 3 and the second servo valve 4 The initial amplitudes of the command signals of the first servo valve 3 and the second servo valve 4 can be calculated based on the oil supply pressure of 1 and the load size. During the vibration process, the controller 11 will continuously detect the signal of the displacement sensor 7 to obtain the actual amplitude of the double-rod symmetrical hydraulic cylinder 5, and compare it with the set target amplitude. If the deviation between the two exceeds the allowable range, it will The calculated initial amplitude is corrected.

(2) according to the frequency and the initial amplitude of the command signal of the first servo valve 3 and the second servo valve 4, utilize formula (1) to obtain the initial command signal of the first servo valve 3 and the second servo valve 4 respectively,

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; t</span>}\\ {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 20</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; t</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In formula (I), y ₁₀ (t) represents the initial command signal of the first servo valve 3, y ₂₀ (t) represents the initial command signal of the second servo valve 4, A ₁₀ represents the value of the command signal of the first servo valve 3 Initial amplitude, A ₂₀ represents the initial amplitude of the command signal of the second servo valve 4, ω ₀ represents the frequency of the command signals of the first servo valve 3 and the second servo valve 4, and t represents time.

其中，k代表检测的次数，且k＝1，2，……，

代表第k次检测时第二伺服阀4的阀芯在正穿越零位时相对于第一伺服阀3的阀芯的相位差，

代表第k次检测时第二伺服阀4的阀芯在负穿越零位时相对于第一伺服阀3的阀芯的相位差。(3) The first servo valve 3 is driven by the current command signal of the first servo valve 3 and the second servo valve 4 is driven by the current command signal of the second servo valve 4 . When step (3) is executed for the first time, the current command signal is the initial command signal in step (2). The controller 11 collects the spool position feedback signals of the first servo valve 3 and the second servo valve 4 respectively, and then obtains the first servo valve 3 and the second servo valve 3 according to the spool position feedback signals of the first servo valve 3 and the second servo valve 4. The zero-crossing phase difference of the spools of the two servo valves 4

Among them, k represents the number of times of detection, and k=1, 2, ...,

Represents the phase difference of the spool of the second servo valve 4 relative to the spool of the first servo valve 3 when it is crossing the zero position during the kth detection,

Represents the phase difference of the spool of the second servo valve 4 relative to the spool of the first servo valve 3 when the spool of the second servo valve 4 negatively crosses the zero position during the kth detection.

Considering that the spool displacement signal may repeat or oscillate at the zero crossing point, in the data processing of the phase difference detection, the first is to judge the time interval between the crossing points, if the interval is too small (such as obviously less than half the signal period ), then it is determined that the crossing point is interference and eliminated. The second is to increase the number of periodic samples of the detection signal and calculate the average value of the phase difference.

是否满足关系式(II)，若满足，则执行步骤(5)，否则执行步骤(6)，(4) Judging the zero-crossing phase difference of the spools of the first servo valve 3 and the second servo valve 4

Whether it satisfies relational formula (II), if so, execute step (5), otherwise execute step (6),

$\left|{\mathrm{\&Delta;\&theta;}}_{P_k}\right|>{\mathrm{\&theta;}}_e$ and $\left|{\mathrm{\&Delta;\&theta;}}_{N_k}\right|>{\mathrm{\&theta;}}_e---\left(\mathrm{II}\right)$

In formula (II), θ _e represents the allowable phase difference when the spools of the first servo valve 3 and the second servo valve 4 are crossing the zero position positively and negatively crossing the zero position;

If (II) is satisfied, it means that there is a large phase difference between the openings of the two servo valves when they cross the zero position positively and negatively. If the phase difference is small, go to step (5). If (II) is not satisfied, it means that after the phase shifting method, the positive and negative crossing phase difference has been greatly reduced. At this time, the phase difference should be further judged and enter step (6).

(5) Utilize formula (III) and (IV) to obtain the current command signal of the first servo valve 3 and the second servo valve 4, and then return to perform step (3),

表示第一伺服阀3的当前指令信号，

表示第二伺服阀4的当前指令信号，

表示第二伺服阀4当前指令信号的移相角度，表示第二伺服阀4上一次指令信号的移相角度，且 In formula (III), formula (IV),

represents the current command signal of the first servo valve 3,

Indicates the current command signal of the second servo valve 4,

Indicates the phase shift angle of the current command signal of the second servo valve 4, Indicates the phase shift angle of the last instruction signal of the second servo valve 4, and

或

是否成立，如果成立，则执行步骤(7)，否则完成对本实用新型电液振动装置的第一伺服阀3和第二伺服阀4的同步控制。(6) Judgment

or

Whether it is established, if established, then execute step (7), otherwise complete the synchronous control of the first servo valve 3 and the second servo valve 4 of the electro-hydraulic vibration device of the present invention.

If the above formula is established, it means that one of the phase differences of the spool displacements of the two servo valves has met the requirements when they are positively crossing and negatively crossing the zero position, but the other phase difference is still relatively large. At this time, step (7) should be entered. The phase difference is further reduced by changing the amplitude of the command signal.

If the above formula is not established, it means that the phase difference of the spool displacements of the two servo valves at the time of positive crossing and negative crossing zero has met the requirements, and the synchronous control is completed at this time.

(7) Utilize formula (V) and (VI) to obtain the current command signal of the first servo valve 3 and the second servo valve 4, and then return to perform step (3),

$p_{1_k}={\mathrm{\&lambda;}}_1{p}_{1_{k-1}},$ $p_{2_k}={\mathrm{\&lambda;}}_2{p}_{2_{k-1}},$ And (λ1-1)Q _n1 = (1-λ ₂ )Q _n2 (VI)

表示第一伺服阀3的当前指令信号的幅值增益，

表示第二伺服阀4的当前指令信号的幅值增益，

表示第一伺服阀3的上一次指令信号的幅值增益，且

表示第二伺服阀4的上一次指令信号的幅值增益，且

λ₁表示第一伺服阀3的指令信号的幅值增益系数，λ₂表示第二伺服阀4的指令信号的幅值增益系数，Q_n1表示第一伺服阀3的额定流量，Q_n2表示第二伺服阀4的额定流量。In formula (V), (VI),

represents the amplitude gain of the current command signal of the first servo valve 3,

represents the amplitude gain of the current command signal of the second servo valve 4,

represents the amplitude gain of the last instruction signal of the first servo valve 3, and

represents the amplitude gain of the last instruction signal of the second servo valve 4, and

λ ₁ represents the amplitude gain coefficient of the command signal of the first servo valve 3, λ ₂ represents the amplitude gain coefficient of the command signal of the second servo valve 4, Q _n1 represents the rated flow rate of the first servo valve 3, Q _n2 represents the Second, the rated flow rate of the servo valve 4.

Formula (VI) is to overcome the influence of the change of servo valve command signal amplitude on the hydraulic system flow, that is, to amplify (reduce) the signal amplitude of the first servo valve 3 while reducing (magnifying) the signal amplitude of the second servo valve 4 Amplitude, and meet the requirement that the increase and decrease of the flow caused by the change of the command signal amplitude cancel each other out.

The above is an example where two servo valves are connected in parallel and the vibrating device vibrates sinusoidally. For two or more servo valves, when the vibrating device moves sinusoidally or other periodic curves, the above method can still be applied to synchronously control the parallel servo valves of the electro-hydraulic vibrating device of the present invention.

As shown in Figure 2 to Figure 4, under the input signal of 50Hz, ±20% of the full stroke, after synchronous control of the electro-hydraulic vibration device of the present invention, the displacement of the spools of the two parallel servo valves when they cross the zero position The phase difference is reduced to around 1°. Under the input signals of other frequencies and other amplitudes, they also exhibit good synchronous control effects, but due to space limitations, they cannot be listed one by one. It can be seen that the electro-hydraulic vibration device of the present invention can meet the requirements of large flow rate and high frequency response of the electro-hydraulic vibration device, and realize the synchronous movement of the valve core when the servo valves are connected in parallel.

Claims (4)

1. the large-flow high-frequency based on the servovalve parallel connection rings electric liquid shake unit, it is characterized in that: comprise oil sources (1), oil sump tank (2), two above servovalves, two rod symmetrical hydraulic cylinder (5), controller (11) and displacement transducers (7); The filler opening of described each servovalve all is connected with oil sources (1), the return opening of each servovalve all is connected with oil sump tank (2), first actuator port of each servovalve all is connected with first hydraulic fluid port of two rod symmetrical hydraulic cylinders (5), and second actuator port of each servovalve all is connected with second hydraulic fluid port of two rod symmetrical hydraulic cylinders (5); Described displacement transducer (7) is connected with the piston rod of two rod symmetrical hydraulic cylinders (5); Described displacement transducer (7) and each servovalve all are electrically connected with described controller (11).

2. the large-flow high-frequency based on the servovalve parallel connection according to claim 1 rings electric liquid shake unit, and it is characterized in that: described servovalve is two.

3. the large-flow high-frequency based on the servovalve parallel connection according to claim 1 rings electric liquid shake unit, it is characterized in that: also comprise acceleration transducer (8), described acceleration transducer (8) is connected with the piston rod of two rod symmetrical hydraulic cylinders (5).

4. the large-flow high-frequency based on the servovalve parallel connection according to claim 1 rings electric liquid shake unit, it is characterized in that: also comprise first pressure transducer (9) and second pressure transducer (10), described first pressure transducer (9) is connected with first hydraulic fluid port of two rod symmetrical hydraulic cylinders (5), and described second pressure transducer (10) is connected with second hydraulic fluid port of two rod symmetrical hydraulic cylinders (5).

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