JP2012077853A - Electromagnetic proportional valve drive control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic proportional valve drive control device that can output PWM signals having a plurality of types of drive frequencies with a simple structure.SOLUTION: First and second electromagnetic proportional valves 1, 2 are controlled by using a control device 4. An arithmetic processing unit 5 of the control device 4 includes first and second signal arithmetic units 6, 7 that outputs first and second PWM signals S1, S2. First and second PWM signal generation units 10, 15 of the first and second signal arithmetic units 6 generate the first and second PWM signals S1, S2 with duty ratios D1, D2 obtained by first and second duty ratio arithmetic units 14. The first and second PWM signal generation units 10, 15 read first and second frequencies F1, F2 from a drive frequency storage unit 18, and set drive frequencies of first and second PWM signals S1, S2 to the first and second frequencies F1, F2 using a reference signal R from an oscillation unit 19.

Description

  The present invention relates to an electromagnetic proportional valve drive control device suitable for use in an electromagnetic proportional valve used in a hydraulic circuit such as a construction machine.

  In general, for example, a construction machine such as a hydraulic excavator uses a plurality of electromagnetic proportional valves for hydraulic control or the like. In such an electromagnetic proportional valve for hydraulic control, load characteristics such as drive frequency differ depending on the hydraulic tolerance of the controlled object and the response characteristics of the hydraulic circuit. For this reason, the structure which can output a PWM signal with multiple types of drive frequency is known as an electromagnetic proportional valve drive control apparatus (for example, refer to patent documents 1). In the electromagnetic proportional valve drive control device described in Patent Document 1, a triangular wave generating unit that generates a triangular wave serving as a reference for a driving frequency based on an oscillation frequency setting resistor, a comparison voltage and a triangular wave are compared, and a PWM signal is output. And a comparator. Then, by switching the oscillation frequency setting resistor, the oscillation frequency of the triangular wave generator is changed, and a PWM signal that matches the characteristics of the solenoid to be driven is output.

JP 2001-338810 A

  By the way, in the above-described prior art, a circuit for switching the oscillation frequency setting resistor is required to change the drive frequency. In addition, in order to simultaneously output PWM signals of a plurality of types of drive frequencies with a single control device, a plurality of triangular wave generators are required according to the types of drive frequencies, which increases manufacturing costs. There's a problem.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an electromagnetic proportional valve drive control device capable of outputting PWM signals at a plurality of types of drive frequencies with a simple configuration. It is in.

  In order to solve the above-described problem, the present invention provides a command value generation unit, a duty ratio calculation unit that calculates a duty ratio based on a command value output from the command value generation unit, and a PWM having the duty ratio. A PWM signal generator for generating a signal; a switching element for energizing a coil of the electromagnetic proportional valve in response to the PWM signal; and a back electromotive force generated in the electromagnetic proportional valve when the switching element is off. A load current recirculation element that recirculates to the input side of the valve, a current / voltage converter that converts the excitation current that flows through the electromagnetic proportional valve into a voltage and uses the voltage as a detection voltage, and takes the detection voltage as a detection value A / D conversion unit, and the duty ratio calculation unit is configured to calculate the duty ratio so that a difference between the command value and the detection value is small. It is applied to the control device.

  A feature of the configuration adopted by the invention of claim 1 is that a plurality of the PWM signal generation units and the switching elements are provided corresponding to a plurality of electromagnetic proportional valves, and are adapted to the characteristics of the electromagnetic proportional valves. A drive frequency storage unit that stores the drive frequency in advance, and an oscillation unit that outputs a reference signal having a predetermined period, and each PWM signal generation unit is driven according to the characteristics of the corresponding electromagnetic proportional valve A drive frequency reading unit that reads a frequency from the drive frequency storage unit, and on and off are switched one or more times in each cycle of the reference signal according to the drive frequency read by the drive frequency reading unit. And a PWM signal output unit that outputs a PWM signal having the duty ratio.

  According to a second aspect of the present invention, the oscillating unit includes a plurality of timers that measure a predetermined period and start in accordance with a predetermined order, and the PWM signal output unit has a predetermined period of each timer when the driving frequency is high The PWM signal having the duty ratio is output as a cycle, and when the drive frequency is low, the PWM signal having the duty ratio is output by setting the total of the predetermined cycles of the plurality of timers as one cycle.

  According to a third aspect of the present invention, the plurality of electromagnetic proportional valves are provided in a hydraulic circuit of a construction machine.

  According to the first aspect of the present invention, each PWM signal generation unit is constituted by the drive frequency reading unit and the PWM signal output unit, so that the drive frequency matched to the characteristics of the electromagnetic proportional valve using the drive frequency reading unit is set to the drive frequency. PWM having a desired duty ratio by switching on and off one or more times in each cycle of the reference signal output from the oscillation unit according to the drive frequency read from the storage unit and read using the PWM signal output unit A signal can be output. For this reason, the plurality of PWM signal generators can simultaneously output PWM signals having different drive frequencies. In addition, since a plurality of PWM signal generation units can use a common drive frequency storage unit and an oscillation unit, it is not necessary to provide a circuit for switching an oscillation frequency setting resistor and a plurality of triangular wave generation units, thereby reducing the manufacturing cost. Can be reduced.

  According to the second aspect of the present invention, the oscillating unit is constituted by a plurality of timers which time each other with a predetermined period and are activated according to a predetermined order. For this reason, the PWM signal output unit can output a PWM signal having a high drive frequency by outputting a PWM signal having a duty ratio with a predetermined cycle of each timer as one cycle. Further, the PWM signal output unit can output a PWM signal having a low driving frequency by outputting a PWM signal having a duty ratio with a total of predetermined periods of a plurality of timers as one period.

  According to the invention of claim 3, since the plurality of electromagnetic proportional valves are provided in the hydraulic circuit of the construction machine, even if a difference in hydraulic resistance and response characteristics of the hydraulic circuit occurs, A PWM signal having a corresponding drive frequency can be output.

It is a block diagram which shows the electromagnetic proportional valve drive control apparatus by embodiment of this invention. It is a flowchart which shows the 1st, 2nd PWM signal arithmetic processing by the arithmetic processing part in FIG. 3 is a flowchart showing PWM signal output processing in FIG. 2. It is a flowchart which shows the 100Hz process in FIG. It is a flowchart which shows the 200Hz process in FIG. It is a flowchart which shows the 400Hz process in FIG. It is a characteristic diagram which shows a 100 Hz PWM signal. It is a characteristic diagram which shows a 200 Hz PWM signal. It is a characteristic diagram which shows a PWM signal of 400 Hz.

  Hereinafter, an electromagnetic proportional valve drive control device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  In FIG. 1, reference numerals 1 and 2 denote first and second electromagnetic proportional valves to be driven and controlled. These electromagnetic proportional valves 1 and 2 are provided in a hydraulic circuit of a construction machine such as a hydraulic excavator, for example. In addition, a solenoid (coil) as an inductive load is provided. These proportional solenoid valves 1 and 2 are connected to a power source 3 serving as a supply source of drive currents I1 and I2 (excitation current) via a control device 4 which will be described later. The opening degrees of the first and second electromagnetic proportional valves 1 and 2 are adjusted according to the drive currents I1 and I2 supplied from the power source 3.

  Reference numeral 4 denotes a control device that controls the first and second electromagnetic proportional valves 1 and 2 by adjusting the drive currents I1 and I2. The control device 4 includes an arithmetic processing unit 5 and first and second drives described later. It is constituted by current circuits 20 and 25.

  An arithmetic processing unit 5 is constituted by, for example, a microcomputer, and the arithmetic processing unit 5 includes first and second signal arithmetic units 6 and 7. The first signal calculation unit 6 includes a first command value P1 corresponding to the opening of the first electromagnetic proportional valve 1 and a first detection voltage V1 corresponding to the drive current I1 of the first electromagnetic proportional valve 1. Based on the above, the first duty ratio D1 is subjected to feedback calculation processing, and the first PWM signal S1 corresponding to the duty ratio D1 is output. On the other hand, the second signal calculation unit 7 performs the second detection corresponding to the second command value P2 corresponding to the opening of the second electromagnetic proportional valve 2 and the drive current I2 of the second electromagnetic proportional valve 2. Based on the voltage V2, the second duty ratio D2 is subjected to feedback calculation processing, and a second PWM signal S2 corresponding to the duty ratio D2 is output.

  Specifically, the first signal calculation unit 6 reduces the difference between the command value generation unit 8 that outputs the first command value P1 and the first command value P1 and the first detection voltage V1. A first duty ratio calculation unit 9 that performs feedback calculation processing on the duty ratio D1 of the PWM signal S1 and a first PWM signal S1 based on the duty ratio D1 output from the first duty ratio calculation unit 9 are generated. And a first PWM signal generator 10 for outputting and a first A / D converter for converting a first detection voltage V1 comprising an analog signal output from a first drive current circuit 20 described later into a digital signal. 11 and a first A / D conversion value storage unit 12 that stores an A / D conversion value (digital value) of the first detection voltage V1 output from the first A / D conversion unit 11. Has been.

  Similarly, the second signal calculation unit 7 performs PWM so that the difference between the command value generation unit 13 that outputs the second command value P2 and the second command value P2 and the second detection voltage V2 becomes small. A second duty ratio calculation unit 14 that performs feedback calculation processing on the duty ratio D2 of the signal S2, and a second PWM signal S2 is generated and output based on the duty ratio D2 output from the second duty ratio calculation unit 14 A second PWM signal generating unit 15 that performs the above operation, and a second A / D conversion unit 16 that converts a second detection voltage V2 composed of an analog signal output from a second drive current circuit 25 described later into a digital signal, and The second A / D conversion value storage unit 17 stores the A / D conversion value of the second detection voltage V2 output from the second A / D conversion unit 16.

  The functional elements of the first and second signal calculation units 6 and 7 are specific calculation processes such as a microcomputer as in the first and second PWM signal calculation processes shown in FIGS. It is realized by software showing.

  The arithmetic processing unit 5 includes a drive frequency storage unit 18 that stores the first and second frequencies F1 and F2 that are the drive frequencies F of the first and second PWM signals S1 and S2. The drive frequency storage unit 18 is configured by a memory such as a ROM or a RAM, for example, and stores in advance the first frequency F 1 that matches the characteristics of the first electromagnetic proportional valve 1 and also the second electromagnetic proportional valve 2. The second frequency F2 that matches the characteristics is stored in advance. At this time, the first and second frequencies F1, F2 may be the same value or different values. The first and second frequencies F1 and F2 are read by the first and second PWM signal generators 10 and 15, respectively. As a result, the first and second PWM signal generators 10 and 15 output the first and second PWM signals S1 and S2 in which the drive frequency F is set to the first and second frequencies F1 and F2, respectively. To do.

  Reference numeral 19 denotes an oscillating unit provided in the arithmetic processing unit 5. The oscillating unit 19 outputs a reference signal R having a predetermined period of 10 ms (100 Hz), for example. The oscillation unit 19 is configured by combining, for example, four timers 19A to 19D provided in the arithmetic processing unit 5. Each of the timers 19A to 19D measures a divided period Ta to Td of 2.5 ms (400 Hz) obtained by dividing one period of the reference signal R into four equal parts as a predetermined period. In addition, the timers 19A to 19D are activated in the order of the first timer 19A, the second timer 19B, the third timer 19C, and the fourth timer 19D as a predetermined order, and are repeatedly activated and timed in this order. For this reason, the time from the start of the first timer 19A to the end of the timing of the fourth timer 19D corresponds to one cycle of the reference signal R.

  Then, the first PWM signal generation unit 10 of the arithmetic processing unit 5 executes first and second PWM signal arithmetic processing described later, thereby performing a reference signal R generated by the oscillating unit 19 according to the first frequency F1. The first PWM signal S1 having a duty ratio D1 is output by switching on and off one or more times in each cycle. Similarly, the second PWM signal generation unit 15 executes first and second PWM signal calculation processes, which will be described later, in each cycle of the reference signal R by the oscillation unit 19 according to the second frequency F2. The second PWM signal S2 having a duty ratio D2 is output by switching between on and off once or a plurality of times.

  Reference numeral 20 denotes a first drive current circuit for supplying a drive current I1 to the first electromagnetic proportional valve 1 in response to the first PWM signal S1 by the first signal calculation unit 6, and the first drive current circuit 20 is The first PWM signal generator 10 and the first A / D converter 11 are connected. The first drive current circuit 20 includes a first switching element 21 for energizing the solenoid of the first electromagnetic proportional valve 1 in response to the first PWM signal S1, and the first switching element 21 being turned off (cut off). State), the first load current return element 22 for returning the back electromotive force generated in the first electromagnetic proportional valve 1 to the input side of the first electromagnetic proportional valve 1 and the first electromagnetic proportional valve 1 are energized. A first current / voltage converter 23 that converts the exciting current to be converted into a voltage and uses the voltage as a first detection voltage V1, and a first detection voltage V1 output from the first current / voltage converter 23. And a first amplifier 24 that outputs the signal to the first A / D converter 11.

  Here, the first load current return element 22 is formed of, for example, a diode having a cathode connected to the first switching element 21 and an anode connected to the ground. The first switching element 21 is formed using, for example, a MOSFET or the like as an element that is turned on and off in response to the first PWM signal S1.

  Reference numeral 25 denotes a second drive current circuit for supplying a drive current I2 to the second electromagnetic proportional valve 2 in accordance with the second PWM signal S2 from the second signal calculation unit 7, and the second drive current circuit 25 is The first drive current circuit 20 is configured in substantially the same manner, and is connected to the second PWM signal generation unit 15 and the second A / D conversion unit 16. For this reason, the second drive current circuit 25 includes a second switching element 26, a second load current return element 27, a second current / voltage converter 28, and a second amplifier 29. Then, the second drive current circuit 25 switches the second switching element 26 on (energized state) and off (shut off state) in response to the second PWM signal S2, and the second electromagnetic proportional valve 2 is switched. While supplying the drive current I2 to the solenoid, the excitation current energized to the second electromagnetic proportional valve 2 is detected as the second detection voltage V2 and outputted to the second A / D converter 16.

  The electromagnetic proportional valve drive control apparatus according to the present embodiment has the above-described configuration. Next, the first and second PWM signal calculation processes by the calculation processing unit 5 will be described with reference to FIGS. explain. In addition, the microcomputer which comprises the arithmetic processing part 5 operate | moves at high speed sufficiently compared with several hundred Hz used as the drive frequency of the 1st, 2nd electromagnetic proportional valves 1 and 2 like several MHz etc., for example. . Therefore, the first and second PWM signal calculation processes are repeatedly executed at a cycle of, for example, about several tens of μs to several hundreds of μs.

  First, in step 1, the first duty ratio D1 is read from the first duty ratio calculation unit 9 as the duty ratio D, and in step 2, the first frequency F1 is read from the drive frequency storage unit 18 as the drive frequency F. . In the next step 3, a PWM signal output process described later is executed to output the first PWM signal S1 having the first frequency F1 at the first duty ratio D1.

  Subsequently, in step 4, the second duty ratio D2 is read from the second duty ratio calculator 14 as the duty ratio D, and in step 5, the second frequency F2 is read from the drive frequency storage 18 as the drive frequency F. Include. In the next step 6, a PWM signal output process to be described later is executed to output a second PWM signal S2 having the second frequency F2 at the second duty ratio D2.

  Next, the PWM signal output processing in FIG. 2 will be described with reference to FIG. In FIG. 3, the drive frequency D (frequency F1, F2) of the first and second electromagnetic proportional valves 1 and 2 is illustrated as an example in which any one of three types of 100 Hz, 200 Hz, and 400 Hz can be selected. is doing.

  First, in step 11, it is determined whether or not the drive frequency F is 100 Hz. If it is determined as “YES” in step 11, the process proceeds to step 12 to execute 100 Hz processing for outputting a 100 Hz PWM signal, and then proceeds to step 16 and returns.

  On the other hand, if “NO” is determined in the step 11, the process proceeds to a step 13 to determine whether or not the driving frequency F is 200 Hz. If “YES” is determined in step 13, the process proceeds to step 14 to execute a 200 Hz process for outputting a 200 Hz PWM signal, and the process proceeds to step 16 to return.

  If “NO” is determined in step 13, the process proceeds to step 15, 400 Hz processing for outputting a 400 Hz PWM signal is executed, and the process proceeds to step 16 and returns.

  Next, 100 Hz processing in FIG. 3 will be described with reference to FIG.

  First, in step 21, it is determined whether or not the duty ratio D is greater than 75%. If “YES” is determined in the step 21, the process proceeds to a step 22, where the first timer 19A counts the division cycle Ta based on the given duty ratio D using the following equation (1). The duty ratio DT [1] is calculated during this time. Based on this duty ratio DT [1], the PWM signal is switched from OFF to ON while the first timer 19A measures the division period Ta. In the following step 23, the duty ratios DT [2] to DT [4] are set to 100% while the second to fourth timers 19B to 19D measure the division periods Tb to Td. Thus, while the second to fourth timers 19B to 19D measure the division periods Tb to Td, the PWM signal is fixed to be on and switched to be off when the first timer 19A is activated. When step 23 is completed, the routine proceeds to step 34 and returns.

  On the other hand, if “NO” is determined in the step 21, the process proceeds to a step 24 to determine whether or not the duty ratio D is larger than 50%. If “YES” is determined in the step 24, the process proceeds to a step 25 to set the duty ratio DT [1] to 0% while the first timer 19A measures the division period Ta. Thus, the PWM signal is fixed to OFF while the first timer 19A measures the division period Ta.

  Next, in step 26, based on the given duty ratio D, the duty ratio DT [2] while the second timer 19B measures the division period Tb is calculated using the following equation (2). . Based on the duty ratio DT [2], the PWM signal is switched from OFF to ON while the second timer 19B measures the division period Tb. In the following step 27, the duty ratios DT [3], DT [4] are set to 100% while the third and fourth timers 19C, 19D measure the division periods Tc, Td. Thus, while the third and fourth timers 19C and 19D measure the division periods Tc and Td, the PWM signal is fixed to be on and switched to be off when the first timer 19A is activated. When step 27 ends, the process moves to step 34 and returns.

  If “NO” is determined in the step 24, the process shifts to a step 28 to determine whether or not the duty ratio D is larger than 25%. If “YES” is determined in the step 28, the process proceeds to a step 29, where the duty ratios DT [1], DT [2] while the first and second timers 19A, 19B measure the division periods Ta, Tb. ] Is set to 0%. As a result, the PWM signal is fixed to OFF while the first and second timers 19A and 19B measure the division periods Ta and Tb.

  Next, in step 30, the duty ratio DT [3] while the third timer 19B measures the division period Tc is calculated based on the given duty ratio D using the following equation (3). . Based on this duty ratio DT [3], the third timer 19C switches the PWM signal from OFF to ON while measuring the division period Tc. In the following step 31, the duty ratio DT [4] is set to 100% while the fourth timer 19D measures the division period Td. Thus, while the fourth timer 19D counts the division period Td, the PWM signal is fixed to be on and switched to off when the first timer 19A is activated. When step 31 ends, the process proceeds to step 34 and returns.

  On the other hand, if “NO” is determined in the step 28, the process proceeds to a step 32, where the duty ratios DT [1] to DT [3 are calculated while the first to third timers 19A to 19C measure the division periods Ta to Tc. ] Is set to 0%. Thus, the PWM signal is fixed to OFF while the first to second timers 19A to 19C measure the division periods Ta to Tc. In the following step 33, based on the given duty ratio D, the duty ratio DT [4] while the fourth timer 19D measures the division period Td is calculated using the following equation (4). Based on the duty ratio DT [4], the fourth timer 19D switches the PWM signal from OFF to ON while counting the division period Td. When step 33 is completed, the routine proceeds to step 34 and returns.

  As a result, the first to fourth timers 19A to 19D can generate a PWM signal having a duty ratio D, with one period being 10 ms, which is the sum of the division periods Ta to Td. As a result, as shown in FIG. 7, the drive frequency F of the PWM signal is set to 100 Hz. Thereby, the 1st, 2nd PWM signal generation parts 10 and 15 can output PWM signals S1 and S2 of 100 Hz. FIG. 7 illustrates the case where the duty ratio D is 62.5%.

  Next, 200 Hz processing in FIG. 3 will be described with reference to FIG.

  First, in step 41, it is determined whether or not the duty ratio D is greater than 50%. If “YES” is determined in step 41, the process proceeds to step 42, and the first timer 19 A counts the division cycle Ta based on the given duty ratio D using the following equation (5). The duty ratio DT [1] during this period and the duty ratio DT [3] during which the third timer 19C measures the division period Tc are calculated. Based on the duty ratios DT [1], DT [3], the first timer 19A switches the PWM signal from OFF to ON while the division period Ta is being measured, and the third timer 19C sets the division period Tc. In the middle of timing, the PWM signal is switched from OFF to ON.

  In the following step 43, the duty ratios DT [2] and DT [4] are set to 100% while the second and fourth timers 19B and 19D measure the division periods Tb and Td. Thus, while the second timer 19B counts the division period Tb, the PWM signal is fixed to be on and switched to be off when the third timer 19C is activated. Similarly, while the fourth timer 19D measures the division period Td, the PWM signal is fixed to be on and switched to be off when the first timer 19A is activated. When step 43 ends, the process moves to step 46 and returns.

  On the other hand, if “NO” is determined in step 41, the process proceeds to step 44, where the duty ratios DT [1] and DT [3 are calculated while the first and third timers 19A and 19C measure the division periods Ta and Tc. ] Is set to 0%. Thus, the PWM signal is fixed to OFF while the first timer 19A measures the division cycle Ta, and the PWM signal is fixed to OFF while the third timer 19C measures the division cycle Tc. In the subsequent step 45, based on the given duty ratio D, the following equation 6 is used to calculate the duty ratio DT [2] while the second and fourth timers 19B and 19D measure the division periods Tb and Td. 2] and DT [4] are calculated. Based on the duty ratios DT [2] and DT [4], the second timer 19B switches the PWM signal from OFF to ON while counting the division cycle Tb, and the fourth timer 19D sets the division cycle Td. In the middle of timing, the PWM signal is switched from OFF to ON. When step 45 ends, the process proceeds to step 46 and returns.

  As a result, the first and second timers 19A and 19B have a total period of divisions Ta and Tb, and the third and fourth timers 19C and 19D have a total period of division periods Tc and Td. A PWM signal having the ratio D can be generated. As a result, as shown in FIG. 8, the drive frequency F of the PWM signal is set to 200 Hz. As a result, the first and second PWM signal generators 10 and 15 can output PWM signals S1 and S2 of 200 Hz. FIG. 8 illustrates the case where the duty ratio D is 62.5%.

  Next, 400 Hz processing in FIG. 3 will be described with reference to FIG.

  In step 51, the duty ratios DT [1] to DT [4] while the first to fourth timers 19A to 19D measure the division periods Ta to Td are set to the given duty ratio D. Based on the duty ratios DT [1] to DT [4], the first to fourth timers 19A to 19D switch the PWM signal from OFF to ON while counting the division periods Ta to Td. When step 51 is completed, the process proceeds to step 52 and returns.

  As a result, a PWM signal having a duty ratio D can be generated with the division periods Ta to Td (Ta to Td = 2.5 ms) of the first to fourth timers 19A to 19D as one period. As a result, as shown in FIG. 9, the drive frequency F of the PWM signal is set to 400 Hz. Thereby, the 1st, 2nd PWM signal generation parts 10 and 15 can output PWM signals S1 and S2 of 400 Hz. FIG. 9 illustrates a case where the duty ratio D is 62.5%.

  The electromagnetic proportional valve drive control apparatus according to the present embodiment has the above-described configuration, and the operation thereof will be described with reference to FIG.

  The first signal calculation unit 6 of the control device 4 is based on the first command value P1 from the first command value generation unit 8 and the detection voltage V1 input from the first A / D conversion unit 11. A first PWM signal S1 is generated and output. At this time, the first switching element 21 is periodically switched on and off based on the first PWM signal S1. Thereby, the drive current I1 is supplied from the power source 3 to the first electromagnetic proportional valve 1 through the first switching element 21, and the opening degree of the first electromagnetic proportional valve 1 is adjusted according to the drive current I1.

  The second signal calculation unit 7 of the control device 4 is based on the second command value P2 from the second command value generation unit 13 and the detection voltage V2 input from the second A / D conversion unit 16. The second PWM signal S2 is generated and output. At this time, the second switching element 26 is periodically switched on and off based on the second PWM signal S2. Thereby, the drive current I2 is supplied from the power source 3 to the second electromagnetic proportional valve 2 through the second switching element 26, and the opening degree of the second electromagnetic proportional valve 2 is adjusted according to the drive current I2.

  Here, the first signal calculation unit 6 includes a first duty ratio calculation unit 9 and a first PWM signal generation unit 10. Then, the first duty ratio calculation unit 9 performs feedback calculation processing on the first duty ratio D1 so that the difference between the first command value P1 and the first detection voltage V1 becomes small. At this time, the first PWM signal generator 10 sets the duty ratio of the first PWM signal S1 based on the duty ratio D1, and reads the first frequency F1 stored in the drive frequency storage unit 18. Thus, the first PWM signal S1 that periodically switches at the frequency F1 is output.

  The second signal calculation unit 7 also includes a second duty ratio calculation unit 14 and a second PWM signal generation unit 15, and the second PWM signal generation unit 15 is generated by the second duty ratio calculation unit 14. Based on the duty ratio D2, the duty ratio of the second PWM signal S2 is set, and the second frequency F2 stored in the drive frequency storage unit 18 is read out, and the second frequency F2 is switched periodically. The PWM signal S2 is output.

  However, in the present embodiment, the first PWM signal generation unit 10 reads the first frequency F1 that matches the characteristics of the first electromagnetic proportional valve 1 from the drive frequency storage unit 18, and according to the frequency F1. The first PWM signal S1 having a desired duty ratio D1 can be output by switching on and off one or more times in each cycle of the reference signal R. Similarly, the second PWM signal generation unit 15 reads the second frequency F2 that matches the characteristics of the second electromagnetic proportional valve 2 from the drive frequency storage unit 18, and each of the reference signals R according to this frequency F2. The second PWM signal S2 having a desired duty ratio D2 can be output by switching on and off one or more times in a cycle.

  For this reason, when the arithmetic processing unit 5 executes the first and second PWM signal output processing (see FIGS. 2 to 6) by software, the first and second PWM signal generation units 10 and 15 Even when the frequencies F1 and F2 are different from each other, the first and second PWM signals S1 and S2 having the frequencies F1 and F2 can be simultaneously output. In addition, since the first and second PWM signal generators 10 and 15 can use the common drive frequency storage unit 18 and the oscillation unit 19, for example, a circuit for switching an oscillation frequency setting resistor or a plurality of circuits as in the prior art. There is no need to provide a single triangular wave generator, and the manufacturing cost can be reduced.

  The oscillating unit 19 is composed of four timers 19A to 19D that time the divided periods Ta to Td and start in accordance with a predetermined order. For this reason, the first and second PWM signal generators 10 and 15 set the division periods Ta to Td of the timers 19A to 19D as one period, for example, a PWM signal S1 having a high drive frequency F such as 400 Hz. , S2 can be output. Further, the first and second PWM signal generators 10 and 15 can set, for example, 200 Hz by setting two or four of the divided periods Ta to Td of the four timers 19A to 19D as one period. In addition, PWM signals S1 and S2 having a low driving frequency F such as 100 Hz can be output.

  Further, since the first and second electromagnetic proportional valves 1 and 2 are configured to be provided in the hydraulic circuit of the construction machine, even when there is a difference in hydraulic resistance and response characteristics of the hydraulic circuit, the respective electromagnetic proportional valves 1 and 2 are provided. PWM signals S1 and S2 having a drive frequency F corresponding to 2 can be output. Thereby, the valve opening degree of the electromagnetic proportional valves 1 and 2 can be adjusted with a desired response.

  In the embodiment described above, steps 2 and 4 in FIG. 2 show a specific example of the drive frequency reading unit, and steps 3 and 6 in FIG. 2 and the PWM signal output processing shown in FIGS. A specific example of the output unit is shown.

  Moreover, although the said embodiment demonstrated and demonstrated the structure which controls the two electromagnetic proportional valves 1 and 2 as an example, you may apply to the structure which controls three or more electromagnetic proportional valves.

  In the embodiment, the first and second PWM signal generators 10 and 15 are configured to output PWM signals S1 and S2 having three types of driving frequencies of 100 Hz, 200 Hz, and 400 Hz. A specific value of the driving frequency is appropriately set based on the response characteristics of the electromagnetic proportional valves 1 and 2.

  In the embodiment, the first and second PWM signal generators 10 and 15 are configured to output PWM signals S1 and S2 having three types of drive frequencies of 100 Hz, 200 Hz, and 400 Hz. However, the present invention is not limited to this, and the first and second PWM signal generators 10 and 15 output, for example, PWM signals S1 and S2 having four types of drive frequencies obtained by adding 800 Hz to 100 Hz, 200 Hz, and 400 Hz. It is good also as a structure.

  In this case, the oscillation unit 19 includes eight timers, and each timer measures a 1.25 ms division period. Then, the first and second PWM signal generators 10 and 15 total the divided periods of the eight timers at 100 Hz to be one period, and the total divided periods of the four timers at 200 Hz to be one period. At 400 Hz, the division periods of the two timers are summed to be one period, and at 800 Hz, the division period of one timer is one period, and each generates and outputs a PWM signal.

  Furthermore, the PWM signal generator may be configured to output PWM signals having five or more types of drive frequencies. The first and second PWM signal generators 10 and 15 output, for example, 133 Hz PWM signals S1 and S2 by adding three of the divided periods Ta to Td of the timers 19A to 19D as one period. It is good also as composition to do.

  Furthermore, in the said embodiment, the electromagnetic proportional valves 1 and 2 used for the hydraulic circuit of a construction machine were mentioned as an example and demonstrated. However, the present invention is not limited to this, and may be applied to an electromagnetic proportional valve used in other hydraulic circuits such as agricultural machines and passenger cars.

DESCRIPTION OF SYMBOLS 1, 2 Solenoid proportional valve 8,13 Command value generation part 9,14 Duty ratio calculation part 10,15 PWM signal generation part 11,16 A / D conversion part 18 Drive frequency preservation | save part 19 Oscillation part 19A-19D Timer 21,26 Switching element 22, 27 Load current return element 23, 28 Current / voltage converter

Claims (3)

A command value generator; a duty ratio calculator for calculating a duty ratio based on a command value output from the command value generator; a PWM signal generator for generating a PWM signal having the duty ratio; and the PWM signal A switching element that energizes the coil of the electromagnetic proportional valve in response to the load, a load current recirculation element that recirculates back electromotive force generated in the electromagnetic proportional valve to the input side of the electromagnetic proportional valve when the switching element is off, The duty ratio calculating unit includes: a current / voltage converter that converts an excitation current to be supplied to the electromagnetic proportional valve into a voltage and uses the voltage as a detection voltage; and an A / D conversion unit that takes the detection voltage as a detection value. Is an electromagnetic proportional valve drive control device configured to calculate the duty ratio so that a difference between the command value and the detection value is small.
A plurality of the PWM signal generators and the switching elements are provided corresponding to a plurality of electromagnetic proportional valves,
A drive frequency storage unit that stores in advance a drive frequency according to the characteristics of each electromagnetic proportional valve; and an oscillation unit that outputs a reference signal having a predetermined constant period;
Each of the PWM signal generation units reads a drive frequency that matches the characteristics of the corresponding electromagnetic proportional valve from the drive frequency storage unit, and depends on the drive frequency read by the drive frequency read unit And a PWM signal output unit that outputs a PWM signal having the duty ratio by switching between ON and OFF one or more times in each cycle of the reference signal. The oscillating unit is configured by a plurality of timers that time a predetermined period and start according to a predetermined order,
The PWM signal output unit outputs a PWM signal having the duty ratio with a predetermined cycle of each timer as one cycle when the drive frequency is high, and outputs a PWM signal having the predetermined cycle of the plurality of timers when the drive frequency is low. The electromagnetic proportional valve drive control device according to claim 1, wherein a PWM signal having the duty ratio is output with a total as one cycle.   The electromagnetic proportional valve drive control device according to claim 1 or 2, wherein the plurality of electromagnetic proportional valves are provided in a hydraulic circuit of a construction machine.

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