Solenoid proportional valve drive mechanism

Abstract

To provide a drive device of a solenoid proportional valve capable of easily obtaining a target pressure or flow rate.SOLUTION: A drive device 100 of a solenoid proportional valve is equipped with a pressure input portion 114 in which a command pressure that is a target pressure is inputted, a pressure current converting portion 116 that converts the command pressure into a current value, a current control portion 118 that supplies a current to a solenoid proportional valve 104 according to the current value, a memory portion 122 that rewritably stores corresponding date in which the command pressure and the current value are associated with each other for each predetermined solenoid proportional valve, and a solenoid proportional valve selecting portion 120 that obtains the corresponding data from the memory portion according to a kind of the solenoid proportional valves when the kind of the solenoid proportional valves is selected, and transmit the corresponding data to the pressure current converting portion. The pressure current converting portion converts the command pressure into the current value by using the corresponding data transmitted from the solenoid proportional valve selecting portion.SELECTED DRAWING: Figure 2

Description

Technical Field

[0005]

[0001] The present invention relates to a driving device for an electromagnetic proportional valve used for pressure adjustment and flow rate adjustment of an oil, air, and water pressure device that uses the pressure and flow rate of a fluid such as hydraulic pressure, pneumatic pressure, or water pressure as a driving source.

Background Art

[0002] An oil, air, and water pressure device is a device that uses the pressure and flow rate of a fluid enclosed therein as a driving source. For example, various operations are performed by adjusting the pressure and flow rate of the fluid using an electromagnetic proportional valve. The electromagnetic proportional valve has a solenoid coil and a valve that opens and closes by an electromagnetic force generated by passing an electric current through the solenoid coil. Thereby, the electromagnetic proportional valve can automatically open and close the valve according to an electric signal and adjust the pressure and flow rate of the fluid. Therefore, if the oil, air, and water pressure device is appropriately designed, it is possible to generate a pressure and flow rate proportional to the current flowing through the solenoid coil of the electromagnetic proportional valve.

[0003] Patent Document 1 describes a control device for a proportional solenoid valve. This control device applies a driving current to the solenoid coil of the proportional solenoid valve, attracts a movable iron piece with an electromagnetic force proportional to the current value flowing through the solenoid coil, and opens and closes the valve at a predetermined opening degree to control the flow rate or pressure of the fluid.

[0004] Specifically, in the control device of Patent Document 1, the input opening command value is corrected to the opening amount of the proportional solenoid valve, and a dither waveform of a force that blocks the static frictional force acting on the movable iron piece to remove the hysteresis that appears when the valve opens and closes according to the opening amount is generated. Further, in the control device, the dither waveform is superimposed on the opening amount to output an instruction current value of the proportional solenoid valve, a supply current corresponding to the instruction current value is applied to the solenoid coil, and the solenoid coil is driven with a constant current with the supply current waveform made to coincide with the instruction current waveform.

[0005] Patent Document 1 states that by driving the solenoid coil with a constant current using the above-mentioned drive current, it is possible to reduce the effects of the hysteresis characteristics of the proportional solenoid valve, temperature changes of the solenoid coil, and fluctuations in the resistance value of the wiring. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-103300 [Overview of the project] [Problems that the invention aims to solve]

[0007] By the way, users of electromagnetic proportional valves need to read a graph of the current-pressure characteristics that have been measured in advance as a characteristic of each electromagnetic proportional valve, in order to adjust the valve opening to obtain the target pressure or flow rate, and then command the target current value to be applied to the solenoid coil.

[0008] Therefore, even though users do not need to be aware of the current value applied to the solenoid coil, they have to read the current-pressure characteristic graph, which is time-consuming and impairs work efficiency. Furthermore, the technology in Patent Document 1 requires users to input an opening command value that they do not need to be aware of, so there is room for improvement in terms of work efficiency.

[0009] In view of these problems, the present invention aims to provide a drive device for an electromagnetic proportional valve that can easily obtain the target pressure and flow rate. [Means for solving the problem]

[0010] To solve the above problems, a typical configuration of the electromagnetic proportional valve drive device according to the present invention comprises: a pressure input unit into which a command pressure, which is a target pressure, is input; a pressure-current conversion unit that converts the command pressure into a current value; a current control unit that supplies current to the electromagnetic proportional valve according to the current value; a storage unit that rewritably stores correspondence data, which associates the command pressure and current value for each predetermined electromagnetic proportional valve; and an electromagnetic proportional valve selection unit that, when a type of electromagnetic proportional valve is selected, acquires correspondence data from the storage unit according to the type of electromagnetic proportional valve and transmits the correspondence data to the pressure-current conversion unit, wherein the pressure-current conversion unit converts the command pressure into a current value using the correspondence data transmitted from the electromagnetic proportional valve selection unit.

[0011] In the above configuration, when the user inputs the command pressure, which is the target pressure, and selects the type of solenoid proportional valve to be used, the solenoid proportional valve selection unit automatically transmits the corresponding data obtained from the storage unit according to the type of solenoid proportional valve to the pressure-current conversion unit. Then, using the transmitted corresponding data, the pressure-current conversion unit converts the command pressure into a current value, and the current control unit supplies current to the solenoid proportional valve according to the current value. The corresponding data is data that associates the command pressure and current value for each predetermined solenoid proportional valve, and is further stored in the storage unit in a rewritable manner.

[0012] This allows the user to directly command the command pressure and select the type of electromagnetic proportional valve to be used, and the current supplied to the electromagnetic proportional valve, i.e., the drive current of the solenoid coil, is automatically controlled to generate the command pressure. In other words, with the above configuration, since the user can directly command the command pressure, the electromagnetic proportional valve can be controlled to easily obtain the command pressure without the user having to be aware of the drive current of the solenoid coil of the electromagnetic proportional valve.

[0013] The corresponding data mentioned above may be function parameters, the entire function, or a conversion table.

[0014] This allows the storage unit to store as corresponding data parameters such as coefficients and constants of a function showing current-pressure characteristics, the entire function (the degree and number of terms of the polynomial variables and their coefficients and constants), or a conversion table that is a correspondence table between current and pressure (including interpolation and extrapolation). Then, simply by the user directly commanding the pressure and selecting the type of electromagnetic proportional valve to be used, the pressure-current conversion unit can convert the commanded pressure into a current value using the corresponding data obtained from the storage unit by the electromagnetic proportional valve selection unit.

[0015] The drive device for the above-mentioned electromagnetic proportional valve may consist of an embedded computer equipped with a pressure input unit, a pressure-current conversion unit, and a current control unit, and a separate setting computer equipped with an electromagnetic proportional valve selection unit and a memory unit.

[0016] Here, the solenoid proportional valve selection unit is used only when setting the solenoid proportional valve and is therefore unnecessary during normal operation. Thus, in actual operation of the solenoid proportional valve, an embedded computer is used, and only when necessary during setting, a separate setting computer can be connected to utilize the solenoid proportional valve selection unit provided in the setting computer, thereby improving convenience. The separate setting computer may be directly connected to the embedded computer on a one-to-one basis, or it may be connected remotely and in a multiple-to-one manner via a network.

[0017] Furthermore, the memory unit needs to store parameters for many types of solenoid proportional valves, databases such as conversion tables, and function execution files. On the other hand, the computer used to drive the solenoid proportional valves is an embedded computer, making it difficult to secure sufficient memory capacity to store a large amount of data due to size and cost constraints. In contrast, the configuration computer can be a general-purpose computer (not an embedded computer), making it easy to equip it with a large-capacity memory unit. Therefore, it can store corresponding data for many types of solenoid proportional valves without being limited by the memory capacity of the embedded computer.

[0018] Furthermore, when a new type of electromagnetic proportional valve is used, the memory unit needs to update the database and add new function blocks. If the firmware of the embedded computer that drives the electromagnetic proportional valve is updated each time, not only will the work become cumbersome, but it may also be difficult to add due to memory capacity limitations. Therefore, by providing a setting computer separate from the embedded computer with a memory unit, such a situation can be avoided, and workability and convenience can be improved.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a driving device for an electromagnetic proportional valve that can easily obtain a target pressure and flow rate.

Brief Description of the Drawings

[0020] [Figure 1] It is a diagram for explaining a system to which the driving device in the embodiment of the present invention is applied. [Figure 2] It is a block diagram showing the functions of the driving device in FIG. 1. [Figure 3] It is a graph showing the current-pressure characteristics of the electromagnetic proportional valve in FIG. 1. [Figure 4] It is a graph showing Equation (2).

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values shown in such embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and the drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit redundant explanations, and elements not directly related to the present invention are not shown.

[0022] FIG. 1 is a diagram for explaining a system 102 to which a driving device 100 according to an embodiment of the present invention is applied. In addition to the driving device 100, the system 102 includes an electromagnetic proportional valve 104, a pressure sensor 106, and a host command computer 108.

[0023] The electromagnetic proportional valve 104 is used for adjusting the pressure or flow rate of a fluid such as hydraulic pressure, pneumatic pressure, or water pressure in a pressure or flow rate adjustment of a hydraulic, pneumatic, or water pressure device using the pressure of the fluid as a driving source. The electromagnetic proportional valve 104 has a solenoid coil and a valve that opens and closes by an electromagnetic force generated by flowing a current through the solenoid coil, automatically opens and closes the valve according to an electric signal, and adjusts the pressure or flow rate of the fluid. In the following, the electromagnetic proportional valve 104 is assumed to adjust the pressure of the oil enclosed in a hydraulic device as an example, but it is not limited thereto, and it may adjust the flow rate of the oil.

[0024] The driving device 100 is a device that drives the electromagnetic proportional valve 104 by supplying a current, that is, a driving current of the solenoid coil, to the electromagnetic proportional valve 104, and includes an embedded computer 110 and a setting computer 112. The setting computer 112 is a general-purpose computer separate from the embedded computer 110, has fewer size and cost constraints than the embedded computer 110, and can secure a sufficient memory capacity.

[0025] The host command computer 108 is an industrial computer, a programmable logic controller (PLC), or the like, and is a pressure command device to which a command pressure, which is a desired target pressure, is input by a user. The input of the command pressure may be performed by various methods such as an analog signal or digital communication. Further, the host command computer 108 outputs a command pressure signal corresponding to the command pressure to the embedded computer 110.

[0026] The pressure sensor 106 measures the actual pressure of the electromagnetic proportional valve 104 and outputs an actual pressure signal corresponding to the actual pressure to the embedded computer 110 of the drive unit 100. However, in system 102, it is not always necessary to use the pressure sensor 106; if the pressure sensor 106 is not used, only the command pressure signal is input to the embedded computer 110.

[0027] Figure 2 is a block diagram showing the functions of the drive unit 100 in Figure 1. The embedded computer 110 of the drive unit 100 includes a pressure input unit 114, a pressure-current conversion unit 116, and a current control unit 118. The setting computer 112 includes an electromagnetic proportional valve selection unit 120, a storage unit 122, and an electromagnetic proportional valve selection user interface (hereinafter, UI124).

[0028] When the pressure sensor 106 is not used, the pressure input unit 114 receives only the command pressure Pref, which is the target pressure, from the higher-level command computer 108. In this case, the pressure input unit 114 outputs the command pressure Pref to the pressure-current conversion unit 116.

[0029] On the other hand, when using the pressure sensor 106, the pressure input unit 114 receives the command pressure Pref in addition to the actual pressure Pact from the pressure sensor 106. The pressure input unit 114 then calculates the command pressure Prefc, which is obtained by correcting the actual pressure Pact to match the command pressure Pref, using the following equation (1) based on the command pressure Pref and the actual pressure Pact, and outputs it to the pressure-current conversion unit 116.

number

[0030] Here, the first term on the right-hand side of equation (1) above is the feedforward control unit for the command pressure Pref. The second to fourth terms on the right-hand side constitute the feedback control unit that makes up the PID control. Furthermore, Kp, Ki, and Kd in the second to fourth terms are the proportional, integral, and derivative gains, respectively, and are appropriately adjusted to values ​​greater than or equal to 0. If Kp=Ki=Kd=0, the feedback term is disabled, and the command pressure Pref in the open state is passed through directly. Note that there are many conventional techniques for determining these gains and control algorithms, and here we have adopted a general method as an example, but other methods may be adopted as appropriate.

[0031] The pressure-current conversion unit 116 converts the command pressure Pref or corrected command pressure Prefc input from the pressure input unit 114 into a current value. Here, the electromagnetic proportional valve 104 has different parameters depending on its type and individual differences, and its current-pressure characteristics also differ (see Figure 3).

[0032] Figure 3 is a graph showing the current-pressure characteristics of the electromagnetic proportional valve 104 shown in Figure 1. The horizontal axis represents the input current, and the vertical axis represents the pressure. Here, as an example, the current-pressure characteristics of three individual electromagnetic proportional valves 104 are shown. As shown in Figure 3, the pressure obtained for a given drive current applied to the solenoid coil differs for each of the three individual electromagnetic proportional valves 104, and each has its own individual current-pressure characteristics.

[0033] Therefore, the pressure-current conversion unit 116 calculates the current value using a function that can be calculated by a computer program that approximates the graph showing the current-pressure characteristics in Figure 3. Specifically, the pressure-current conversion unit 116 performs the inverse conversion of the current-pressure characteristics using the following equation (2) to convert the pressure into a drive current.

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[0034] Figure 4 is a graph illustrating equation (2). As shown in the graph in Figure 4, in this case, as a current-pressure characteristic, no pressure is generated up to a certain current ia, and when the current exceeds ia, the pressure increases proportionally for a proportionality constant α > 0. There is also a limit to the current that can flow, which is denoted as ib. Furthermore, these currents ia and ib and the proportionality constant α are different parameters (also called parameter sets) for each individual electromagnetic proportional valve 104.

[0035] The parameters for each of these individual solenoid proportional valves 104 are transmitted from the solenoid proportional valve selection unit 120 of the setting computer 112 to the pressure-current conversion unit 116 of the embedded computer 110. Specifically, the storage unit 122 stores rewritable correspondence data for each predetermined solenoid proportional valve 104, which associates the command pressure with the current value. The correspondence data includes parameters such as coefficients and constants of a function that shows the current-pressure characteristics, the entire function (the degree and number of terms of the polynomial variables and their coefficients and constants), or a conversion table that is a current-pressure correspondence table (including interpolation and extrapolation). The UI 124 is an interface for the user to select the type of solenoid proportional valve 104 to use.

[0036] When the user selects the type of electromagnetic proportional valve 104 to be used using the UI 124, the electromagnetic proportional valve selection unit 120 reads and obtains the parameters corresponding to the selected electromagnetic proportional valve 104 from the storage unit 122. Furthermore, the electromagnetic proportional valve selection unit 120 transmits the obtained parameters to the pressure-current conversion unit 116 using digital communication or the like.

[0037] The pressure-current conversion unit 116 then uses the corresponding data transmitted from the electromagnetic proportional valve selection unit 120 to convert the command pressure into a current value based on equation (2) above, and outputs this current value to the current control unit 118. The current control unit 118 supplies a drive current to the electromagnetic proportional valve 104 according to the current value.

[0038] In this way, the drive unit 100 allows the user to input a command pressure, which is the target pressure, and select the type of electromagnetic proportional valve 104 to be used. The electromagnetic proportional valve selection unit 120 then automatically transmits the corresponding data obtained from the storage unit 122 according to the type of electromagnetic proportional valve 104 to the pressure-current conversion unit 116. Using the transmitted corresponding data, the pressure-current conversion unit 116 converts the command pressure into a current value, and the current control unit 118 supplies current to the electromagnetic proportional valve 104 according to the current value.

[0039] As a result, with the drive unit 100, the user can directly command the command pressure and select the type of electromagnetic proportional valve 104 to be used, and the drive current supplied to the solenoid coil of the electromagnetic proportional valve 104 will be automatically controlled to generate the command pressure. In other words, with the drive unit 100, because the user can directly command the command pressure, the user can easily obtain the command pressure by controlling the electromagnetic proportional valve 104 without having to be aware of the drive current of the solenoid coil of the electromagnetic proportional valve 104.

[0040] In system 102, the electromagnetic proportional valve selection unit 120 is used only when setting the electromagnetic proportional valve 104, and is therefore unnecessary during normal operation of the electromagnetic proportional valve 104. Therefore, in the drive unit 100, a low-performance embedded computer 110 is used for the actual operation of the electromagnetic proportional valve 104. A separate, high-performance setting computer 112 is connected only when necessary for setting, allowing the electromagnetic proportional valve selection unit 120 of the setting computer 112 to be used, thereby improving convenience. The separate setting computer 112 may be directly connected to the embedded computer 110 on a one-to-one basis, or it may be a server-client configuration connected remotely and in a many-to-one manner via a network.

[0041] Furthermore, the memory unit 122 needs to store parameters for many types of electromagnetic proportional valves 104, databases such as conversion tables, and function execution files. On the other hand, since the computer for driving the electromagnetic proportional valves 104 is an embedded computer 110, it is difficult to secure sufficient memory capacity to store a large amount of data due to size and cost constraints. In contrast, the drive device 100 can use a general-purpose computer (not an embedded computer: for example, a personal computer or tablet terminal) for the setting computer 112, making it easy to equip the memory unit 122 with a large capacity. As a result, the setting computer 112 can store corresponding data for many types of electromagnetic proportional valves 104 without being limited by the memory capacity of the embedded computer 110.

[0042] Furthermore, if a new type of electromagnetic proportional valve 104 is used, the memory unit 122 needs to update its database or add new function blocks. If the firmware of the embedded computer 110 that drives the electromagnetic proportional valve 104 were to be updated each time, it would not only be a cumbersome task, but due to memory capacity limitations, adding the new functions might even be difficult. In contrast, the drive unit 100 avoids this problem by having a separate configuration computer 112, which is separate from the embedded computer 110, equipped with the memory unit 122, thereby improving work efficiency and convenience.

[0043] The electromagnetic proportional valve selection unit 120 may also read the entire function, which is corresponding data tailored to the characteristics of the electromagnetic proportional valve 104 selected by the user, from the storage unit 122 and transmit this entire function to the pressure-current conversion unit 116. In this case, the storage unit 122 stores the function representing the characteristics of the selected electromagnetic proportional valve 104 as separate library software, and the electromagnetic proportional valve selection unit 120 selects that library software and transfers it to the embedded computer 110. As a result, the pressure-current conversion unit 116 can use the transferred library software to convert the command pressure into a current value. The electromagnetic proportional valve selection unit 120 may also transmit the parameters necessary when calculating using the entire function to the pressure-current conversion unit 116.

[0044] Furthermore, the electromagnetic proportional valve selection unit 120 may read a conversion table, which is corresponding data matched to the characteristics of the electromagnetic proportional valve 104 selected by the user, from the storage unit 122 and transmit this conversion table to the pressure-current conversion unit 116. In this case, the pressure-current conversion unit 116 can use the transmitted conversion table to convert the command pressure into a current value.

[0045] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0046] The present invention can be used as a drive device for electromagnetic proportional valves used in pressure adjustment and flow rate adjustment of hydraulic, pneumatic, and hydrostatic equipment that uses the pressure and flow rate of fluids such as hydraulics, pneumatics, and water pressure as drive sources. [Explanation of symbols]

[0047] 100…Drive unit, 102…System, 104…Solenoid proportional valve, 106…Pressure sensor, 108…Higher-level command computer, 110…Embedded computer, 112…Setting computer, 114…Pressure input unit, 116…Pressure-current conversion unit, 118…Current control unit, 120…Solenoid proportional valve selection unit, 122…Storage unit, 124…User interface for solenoid proportional valve selection

Claims

1. A pressure input section into which the command pressure, which is the target pressure, is input, A pressure-current conversion unit that converts the command pressure into a current value, A current control unit that supplies current to an electromagnetic proportional valve according to the aforementioned current value, A memory unit that stores, in a rewritable format, corresponding data for converting command pressure into current values ​​for each predetermined solenoid proportional valve, The system includes an electromagnetic proportional valve selection unit which, when the type of electromagnetic proportional valve is selected, acquires corresponding data from the storage unit according to the type of electromagnetic proportional valve and transmits the corresponding data to the pressure-current conversion unit, The pressure-current conversion unit uses the corresponding data transmitted from the electromagnetic proportional valve selection unit to convert the command pressure into a current value. The current control unit is characterized by supplying current to the electromagnetic proportional valve according to the current value converted by the pressure-current conversion unit, thereby providing a drive device for an electromagnetic proportional valve.

2. The drive device for an electromagnetic proportional valve according to claim 1, characterized in that the corresponding data is a function parameter, the entire function, or a conversion table.

3. The drive device for the electromagnetic proportional valve, An embedded computer comprising the pressure input unit, the pressure-current conversion unit, and the current control unit, The electromagnetic proportional valve drive device according to claim 1 or 2, comprising the electromagnetic proportional valve selection unit and the storage unit, and comprising the built-in computer and a separate setting computer.

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