JP2017162308A - Proportional solenoid control valve and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate hysteresis of the flow rate of hydraulic fluid or the like, without complicating a structure.SOLUTION: A controller of a proportional valve comprises: an operating portion for accepting input of a desired flow rate; a solenoid to which a control current is applied; a valve body driven by the solenoid; and an element for detecting a direction of operation, which detects increase or decrease of an amount of operation of the operating portion. The controller detects the amount of operation of the operating portion, detecting increase or decrease of the amount of operation. When the amount of operation increases, the controller refers to a first excitation current map with the amount of operation as a parameter, thus determining a magnitude of an excitation current. When the amount of operation decreases, the controller refers to a second excitation current map with the amount of operation as a parameter, thus determining the magnitude of the excitation current. The controller performs the control for applying the excitation current of the determined magnitude, to the solenoid.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electromagnetic proportional control valve provided in a hydraulic circuit mounted on a cargo handling device or the like of an industrial vehicle, and a control method therefor.

  2. Description of the Related Art Conventionally, it has been widely practiced to provide a control valve for controlling the flow rate of hydraulic fluid and other fluids in a hydraulic circuit mounted on a cargo handling device of an industrial vehicle. As one type of this type of control valve, an electromagnetic proportional control valve having a mode in which a valve body is displaced by a desired amount by exciting a solenoid to obtain a desired opening degree has been widely used.

  As a technique for controlling the opening degree of the electromagnetic proportional control valve, the following is known. That is, the storage device stores an operation speed map in which the operation amount for the lever as the operation unit and the desired operation speed of the loading platform are stored in association with each other, and the flow rate of the hydraulic fluid and the magnitude of the excitation current applied to the solenoid of the solenoid valve Is stored in advance, and a sensor for detecting the operation amount of the lever is provided, and the desired operation speed of the loading platform is set using the operation amount corresponding to the output signal of the sensor as a parameter. It is widely practiced to determine the magnitude of the exciting current using the flow rate of the working fluid corresponding to the operating speed as a parameter, and to apply the determined magnitude of exciting current to the solenoid.

  By the way, when changing the opening degree by applying an excitation current to the solenoid, the opening degree when applying the same magnitude of excitation current is different when increasing the opening degree and when reducing the opening degree. There is a problem called hysteresis. That is, when the opening is increased and when the opening is decreased, the flow rate of the hydraulic fluid is different even when the operation amount of the operation unit is the same, and it is difficult to perform minute control that makes the operator feel uncomfortable. There is a problem.

  In order to alleviate this problem, the invention described in Patent Document 1 includes a first spring having a small spring constant that operates in a small output region and a second spring having a large spring constant that operates in a large output region. (For example, refer to Patent Document 1).

  However, when such a configuration is adopted, the first and second springs described above need to be prepared, which causes another problem that the structure becomes complicated. Furthermore, even when the operation amount of the operation unit is the same as described above, the difference in the flow rate of the hydraulic fluid or the like between when the opening degree is increased and when the opening degree is decreased becomes small. It does not disappear. For this reason, it has not been possible to solve the problems such as the above-described problem that the operator feels uncomfortable and that minute control is difficult.

JP-A-61-39111

  The present invention pays attention to the above points, and an object of the present invention is to eliminate the hysteresis of the flow rate of the hydraulic fluid and the like without complicating the structure.

  In order to solve the above problems, an electromagnetic proportional control valve and a control method thereof according to the present invention have the following configurations.

  That is, the electromagnetic proportional control valve according to the present invention includes an operation unit that receives an input of a desired flow rate, a sensor that detects an operation amount for the operation unit, and a control that determines the magnitude of the control current using the operation amount as a parameter. And a solenoid to which a control current having a magnitude determined by the control device is applied, and a valve body driven by the solenoid, and the control device has an operation amount corresponding to the output signal of the sensor. The desired operating speed of the loading platform is determined as a parameter, the magnitude of the exciting current is determined using the flow rate of the hydraulic fluid corresponding to this operating speed as a parameter, and the excitation current of the determined magnitude is applied to the solenoid. And further comprising an operation direction detection element for detecting an increase or decrease in the operation amount with respect to the operation unit, and The control for determining the magnitude of the excitation current by the control device is different depending on whether the operation direction detection element detects an increase in the operation amount or a decrease in the operation amount. This is done by referring to.

  The electromagnetic proportional control valve control method according to the present invention includes an operation unit that receives an input of a desired flow rate, a solenoid to which a control current is applied, a valve body that is driven by the solenoid, and the operation unit. A method for controlling an electromagnetic proportional control valve having an operation direction detection element for detecting an increase or decrease in an operation amount, the step of detecting an operation amount for an operation unit, and detecting an increase or decrease in the operation amount A step of determining a magnitude of an excitation current by referring to a first excitation current map using the operation amount as a parameter when the operation amount is increasing; and a case where the operation amount is decreasing And determining a magnitude of the excitation current by referring to a second excitation current map using the manipulated variable as a parameter, and The magnitude of the excitation current was carried out the step of applying to the solenoid.

  In this case, the magnitude of the excitation current is determined with reference to different excitation current maps when the increase in the operation amount is detected and when the decrease in the operation amount is detected. Therefore, in each case, an excitation current having an appropriate magnitude corresponding to a desired flow rate can be applied to the solenoid, and therefore, a malfunction that causes the operator to feel uncomfortable due to the flow rate hysteresis of the hydraulic fluid, The problem that minute control is difficult can be solved.

  Further, if the control device further includes a flow rate detection element for detecting the flow rate, and the control device stores the operation amount with respect to the operation unit and the flow rate detected by the flow rate detection element, the electromagnetic proportional control It is possible to cope with individual differences of valves and changes with time.

  According to the present invention, the hysteresis of the flow rate of hydraulic fluid or the like can be eliminated without complicating the structure.

Schematic of the hydraulic circuit used for the industrial vehicle which concerns on one Embodiment of this invention. Schematic which shows the exciting current map which concerns on this embodiment. The flowchart which shows the procedure of control by a loading platform raising / lowering control program. The flowchart which shows the procedure of control by a map update program.

  Hereinafter, an embodiment of the present invention will be described.

  The industrial vehicle 1 of this embodiment is equipped with an actuator 3 that drives a loading platform 2 on which a load is to be loaded, and a hydraulic circuit 4 as shown in FIG.

  In the present embodiment, the actuator 3 raises the loading platform 2 by receiving the hydraulic fluid supplied to the first cylinder chamber 31 and also receives the rod 33 by receiving the hydraulic fluid supplied to the second cylinder chamber 32. This is a hydraulic actuator 3 that lowers the loading platform 2 through the hydraulic actuator 3. As described above, the actuator 3 is supplied with hydraulic fluid via the hydraulic circuit 4.

  The hydraulic circuit 4 is connected to a motor M as a driving source, and supplies a hydraulic pump 41 for supplying hydraulic pressure to the actuator 3, and hydraulic fluid that flows into the actuator 3 through the hydraulic pump 41. An electromagnetic proportional control valve (hereinafter referred to as a proportional valve 42), which is a valve whose opening degree can be changed so that the amount can be changed, and a tank 43 for storing hydraulic fluid from the tank 43 through the hydraulic pump 41. An input passage 44 that connects to the proportional valve 42, a first output passage 45 that connects the proportional valve 42 and the first cylinder chamber 31, and the proportional valve 42 and the second cylinder chamber 32. A second output passage 46 to be connected, a discharge passage for connecting the proportional valve 42 and the tank 43 to return the hydraulic fluid discharged from the first or second cylinder chambers 31, 32 to the tank 43. 4 When, and a through-passage 48 for returning the hydraulic fluid discharged from the hydraulic pump 41 to the tank 43 with no load. The proportional valve 42 applies a current to the solenoid 42a to drive the valve body 42b, thereby blocking between the input passage 44 and the first and second output passages 45 and 46 and the input passage. 44, a neutral state in which the through passage 48 is communicated, a rising state in which the input passage 44 and the first output passage 45 are communicated, and the second output passage 46 and the discharge passage 47 are communicated, and The input passage 44 and the second output passage 46 can communicate with each other, and the first output passage 45 and the discharge passage 47 can communicate with each other. The proportional valve 42 can change the opening degree in the ascending state and the descending state. Further, the proportional valve 42 includes a control device 42c for controlling the flow rate of the hydraulic fluid supplied to the actuator 3 through the hydraulic circuit 4, and an operation unit for receiving an operation for controlling the lifting speed of the loading platform 2. The operation lever 42d is provided with a position sensor 42e that detects the position of the operation lever 42d, in other words, the operation amount V with respect to the operation lever 42d. In addition, in the present embodiment, a pressure sensor 49 that is a flow rate detection element is provided in the first output passage 45 in order to detect the flow rate of the hydraulic fluid. The pressure sensor 49 outputs a hydraulic pressure signal p indicating the flow rate of the hydraulic fluid toward the control device 42c.

  The operation lever 42d accepts a selection input for setting the proportional valve 42 to the neutral state, the raised state, or the lowered state. More specifically, the operation lever 42d selectively takes any one of a neutral position, a raised position, and a lowered position. The position sensor 42e outputs a lever state signal a toward the control device 42c. The lever state signal a includes information indicating whether the operation lever 42d is in the neutral position, the raised position, or the lowered position, and information indicating the operation amount V of the operation lever 42d.

  The control device 42c is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. Further, the lever state signal a from the position sensor 42e and the hydraulic pressure signal p from the pressure sensor 49 are input to the input interface of the control device 42c. On the other hand, an opening / closing signal e for changing the opening degree is output from the output interface of the control device 5 to the solenoid 42a of the proportional valve 42.

  Therefore, in the present embodiment, in a predetermined area of the memory, a flow rate map indicating the correspondence between the operation amount V of the operation lever 42d indicated by the lever state signal a and a desired flow rate, and the operation amount V are increased. A first excitation current map shown by a solid line X in FIG. 2 that associates the desired flow rate with the magnitude of the excitation current, and the desired flow rate and the magnitude of the excitation current when the manipulated variable V decreases. The second excitation current map indicated by the broken line Y in FIG.

Further, in another predetermined area of the memory, it is executed when the operation lever 42d receives an operation for starting the raising / lowering operation, and the CPU executes the lever state signal a from the position sensor 42e. Acquired and performs control to gradually change and maintain the opening degree of the proportional valve 42 so as to be an opening degree corresponding to a flow rate for raising and lowering the loading platform 2 at a desired speed (hereinafter referred to as a target value of the flow rate). A loading platform lifting control program is built in. This cargo bed raising / lowering control program is executed every predetermined time. More specifically, the operation amount V of the operation lever 42d indicated by the lever state signal a is received, a target value of the flow rate corresponding to the operation amount V is acquired, and the operation amount V is the operation amount V ₀ at the previous execution. If the manipulated variable V is increasing, the magnitude of the exciting current is determined with reference to the first exciting current map, and the proportional valve 42 is determined. When the manipulated variable V decreases, the magnitude of the exciting current is determined with reference to the second exciting current map and applied to the solenoid 42a of the proportional valve 42. Take control. That is, in the present embodiment, the position sensor 42e and the control device 42c cooperate to function as an operation direction detection element.

  Hereinafter, the control procedure by the cargo bed lifting control program will be described below with reference to FIG. 3 which is a flowchart.

First, a lever state signal a indicating the operation amount V of the operation lever 42d is received (step S1), and a flow rate target value corresponding to the operation amount V indicated by the lever state signal a is acquired (step S2). Next, it is determined whether the operation amount V has increased or decreased from the operation amount V ₀ at the previous execution (step S3). When the manipulated variable V is larger than the manipulated variable V ₀ at the previous execution, the magnitude of the exciting current is determined by referring to the first exciting current map using the target value of the flow rate as a parameter ( In step S4), the voltage is applied to the solenoid of the proportional valve 42 (step S5). On the other hand, when the operation amount V is smaller than the operation amount V ₀ at the previous execution, the magnitude of the excitation current is determined by referring to the second excitation current map using the target value of the flow rate as a parameter. (Step S6), and the voltage is applied to the solenoid 42a of the proportional valve 42 (Step S5). Then, the operation amount V is stored as the operation amount V ₀ at the previous execution (step S7).

  Furthermore, in the present embodiment, the operation amount V for the operation lever 42d indicated by the lever state signal a and the actual flow rate indicated by the hydraulic pressure signal p from the pressure sensor 49 are stored in association with each other in another predetermined area of the memory. Built-in map update program. This map update program is executed in parallel with the cargo bed raising / lowering control program.

  Hereinafter, the control procedure by the map update program will be described below with reference to FIG. 4 which is a flowchart.

  First, the lever state signal a indicating the operation amount V of the operation lever 42d is received (step S11), and then the hydraulic pressure signal p indicating the hydraulic pressure of the hydraulic fluid is received (step S12). After the processes of step S11 and step S12 are executed a predetermined number of times, for example, 10 times (step S13), the relationship between the manipulated variable V and the hydraulic pressure of the hydraulic fluid is obtained by a method such as linear approximation (step S14). Then, the operation amount stored in the hydraulic fluid map and the flow rate obtained from the relationship obtained in step S14 using this operation amount V as a parameter are overwritten in the flow rate map (step S15).

  According to the present embodiment, as described above, when an increase in the operation amount V is detected, the magnitude of the excitation current is determined with reference to the first excitation current map, while the operation amount V is determined. When a decrease in the current is detected, the magnitude of the excitation current is determined with reference to the second excitation current map. In each case, an appropriate excitation current corresponding to the desired flow rate is supplied to the solenoid. Can be applied. Therefore, it is possible to solve the problem that makes the operator feel uncomfortable due to the hysteresis of the flow rate of the hydraulic fluid, and the problem that it is difficult to perform minute control.

  In addition, a hydraulic pressure sensor is further provided, and the control device associates the operation amount with respect to the operation lever 42d and the flow rate detected by the hydraulic pressure sensor 49 and overwrites the flow rate map. It is possible to cope with individual differences of the valve 42 and changes with time.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, the operation amount for the operation unit and the flow rate of the hydraulic fluid detected by the hydraulic pressure sensor are associated, and the flow rate of the hydraulic fluid detected by the hydraulic pressure sensor is overwritten on the flow map as a new flow rate target value. The processing is performed, but in order to make the actual flow rate coincide with the flow rate corresponding to the manipulated variable, the magnitude of the applied current is associated with the flow rate of the hydraulic fluid detected by the hydraulic pressure sensor, and the excitation current map is overwritten. You may do it. Of course, the above-described overwriting process of the flow rate map or exciting current map may be omitted.

  In addition, various changes may be made without departing from the spirit of the present invention.

42 ... Electromagnetic proportional control valve (proportional valve)
42a ... Solenoid 42b ... Valve body 42c ... Control device 42d ... Operation lever 42e ... Operation amount sensor

Claims (4)

An operation unit that receives an input of a desired flow rate, a sensor that detects an operation amount for the operation unit, a control device that determines the magnitude of a control current using the operation amount as a parameter, and a size determined by the control device A solenoid to which a control current of 1 is applied, and a valve body driven by the solenoid,
The control device uses the operation amount indicated by the output signal of the sensor as a parameter, determines the magnitude of the excitation current corresponding to the flow rate of the hydraulic fluid to obtain the desired operating speed of the cargo bed indicated by the operation amount, and determines An electromagnetic proportional control valve that performs control to apply an exciting current of a magnitude to the solenoid,
The control device further includes an operation direction detection element that detects an increase or decrease in the operation amount with respect to the operation unit, and the control device detects the magnitude of the excitation current, and the operation direction detection element increases the operation amount. An electromagnetic proportional control valve that is configured to refer to different maps depending on whether or not a decrease in the manipulated variable is detected. The electromagnetic proportional control valve according to claim 1, further comprising a flow rate detection element for detecting a flow rate, and wherein the control device stores an operation amount for the operation unit and a flow rate detected by the flow rate detection element in association with each other. An operation unit that receives an input of a desired flow rate, a solenoid to which a control current is applied, a valve body that is driven by the solenoid, and an operation direction detection element that detects an increase or decrease in an operation amount with respect to the operation unit. A control method of an electromagnetic proportional control valve,
A step of detecting an operation amount for the operation unit;
Detecting an increase or decrease in the operation amount;
Determining the magnitude of the excitation current by referring to a first excitation current map using the operation quantity as a parameter when the operation quantity is increasing;
Determining the magnitude of the excitation current by referring to a second excitation current map using the operation quantity as a parameter when the operation quantity is decreasing;
And a control method of an electromagnetic proportional control valve that performs a step of applying an excitation current having a determined magnitude to the solenoid. A control method of an electromagnetic proportional control valve further comprising a flow rate detection element for detecting a flow rate,
The method of controlling an electromagnetic proportional control valve according to claim 3, further comprising the step of storing the operation amount for the operation unit and the flow rate detected by the flow rate detection element in association with each other.

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