JPH1078156A - Solenoid valve control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form a control device using a small number of parts for adjusting the opening of a solenoid valve with high accuracy via the measurements of the valve of electric current flowing across an electromagnetic solenoid. SOLUTION: A resistor R is connected in series to a conductive system between a transistor 23 and a solenoid S driven by use of intermittent signals and at the time of feeding electric current to the solenoid S, a potential difference across the resistor R is amplified with a differential amplifier 25 and fed back. Also, a control device 22 is fitted for feeding a target value of electric current to an electric power system via the adjustment of the duty ratio of the intermittent signals to drive the solenoid S on the basis of the feedback signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an electromagnetic valve whose opening is adjusted by a current value supplied to an electromagnetic solenoid, and controls a current value supplied to this electromagnetic valve to achieve a target opening degree. The present invention relates to an improvement in a control device for a solenoid valve configured to obtain the following.

[0002]

2. Description of the Related Art Conventionally, as an example of a control device for an electromagnetic valve configured as described above, which is provided in an agricultural tractor, there is one disclosed in Japanese Patent Application Laid-Open No. 3-292806. Uses an electromagnetic proportional control valve for raising and lowering the lift arm, the electromagnetic proportional control valve uses a first valve for raising control, a second valve for adjusting a pilot pressure for the first valve, and a lowering control. And a fourth valve for adjusting the presence of a pilot for the third valve.
A second valve and a fourth valve are configured such that an opening degree proportional to the current value is obtained by adjusting a current value supplied to the solenoid. A signal system for providing a resistor in series with a ground-side conductive system based on the electromagnetic solenoid so as to measure a current value sent to each of the three solenoids, and feeding back a voltage signal from the resistor to a control device. Is formed, a current value actually supplied to the electromagnetic solenoid is measured to enable precise control.

[0003]

However, as in the prior art, the current flowing through the electromagnetic solenoid is further passed to the resistor, and this current is converted into a voltage signal by the resistor and fed back to the control device. For example, in the case where the resistor is arranged inside the control device, it is necessary to draw a power line for flowing the current flowing through the electromagnetic solenoid to the resistor to the control device, and the resistor is arranged at a position near the electromagnetic solenoid However, since a signal line is required to feed back the voltage signal from the resistor to the control device, not only long wiring is required but also wiring is troublesome, and There is room for

An object of the present invention is to configure a control device for measuring the value of a current supplied to an electromagnetic solenoid and adjusting the opening of an electromagnetic valve so that it can be easily assembled with a small number of components.

[0005]

According to a first aspect of the present invention, as described at the beginning, an electromagnetic valve whose opening is adjusted by a current value supplied to an electromagnetic solenoid is provided. In a control device for an electromagnetic valve configured to obtain a target opening degree by controlling a current value supplied to the electromagnetic valve, a current adjusting unit that adjusts a current value supplied to the electromagnetic solenoid, the electromagnetic solenoid and A resistor is inserted in series in the conductive system between the two, and a feedback means for feeding back a signal converted into a voltage signal by the resistor is provided. Its operation is as follows.

A second feature of the present invention (claim 2) is that, in claim 1, the feedback means is based on a potential difference between a terminal on a current adjusting means side and a terminal on an electromagnetic solenoid side in the resistor. It is of a differential type that determines the value of the current supplied to the electromagnetic solenoid, and its operation is as follows.

According to a third feature of the present invention (claim 3), in claim 2, the current adjusting means supplies an intermittent current to the electromagnetic solenoid, and supply of the intermittent current to the electromagnetic solenoid by adjusting a duty ratio of the intermittent current. In addition to being configured to adjust the current value, the device further comprises voltage applying means for applying a bias voltage to a signal system from a terminal on the current adjusting means side and a terminal on the electromagnetic solenoid side in the resistor, The operation is as follows.

According to the first feature, the current from the current adjusting means flows to the electromagnetic solenoid after flowing through the resistor, and the current flowing through the resistor is equal to the current flowing through the electromagnetic solenoid. Since they are equal, it is possible to adjust the current by the current adjusting means based on the voltage signal obtained by this resistor, and furthermore, in this configuration, a configuration in which the current flowing through the electromagnetic solenoid flows through the resistor as in the conventional example is required. Therefore, it is possible to arrange the current adjusting means and the resistor inside or near the control device to shorten the wiring of the feedback means. Further, in the present invention, it is not necessary to convert the current flowing through the electromagnetic solenoid through the resistor into a voltage signal, so that the current flows through a common member such as a vehicle body and a chassis, so-called body earthing can be performed. Not only can be further simplified, but also a configuration in which one terminal of the solenoid of the solenoid valve is grounded to the body of the solenoid valve can be adopted, and the solenoid valve can be simplified.

According to the second feature, since the voltage between both terminals of the resistor is measured, the current adjusting means adjusts the current value by the duty ratio of the intermittent current, so that accurate current values can be obtained even if the current value fluctuates. The current value can be measured.

The intermittent current is turned on (ON) in a short time.
State) and a cutoff state (OFF state) are generated alternately. When this intermittent signal is supplied to the electromagnetic solenoid, a counter electromotive force is generated by the electromagnetic solenoid at the moment when the current is cut off. However, according to the third feature,
Since a voltage is obtained by adding the voltage generated at both terminals of the resistor and the bias voltage, the bias voltage is added even if the voltage at both ends of the resistor falls to a negative potential due to the back electromotive force. It is possible to obtain a potential, and the current value supplied to the electromagnetic solenoid in the intermittent current OFF state is also measured with a signal for feedback in the positive potential range to accurately grasp the current value supplied to the electromagnetic solenoid. Thus, the solenoid valve can be controlled.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a backhoe A and a dozer device B are provided with respect to a swivel 2 configured to be able to travel by a crawler traveling device 1, and a backhoe as a working vehicle is provided with a steering cabin C. Have been.

The swivel base 2 is supported on the crawler traveling device 1 so as to be swivelable around an axis in a vertical position, and includes a swivel motor 3 for performing a swivel operation of the swivel base 2. Further, the backhoe apparatus A is supported by a boom 4 which is swingably supported around an axis centered in a lateral position with respect to the swivel base 2, and swings around an axis centered in a sideways position with respect to a swing end of the boom 4. An arm 5 movably connected thereto, and a bucket 6 oscillatably connected around an axis centered in a lateral position with respect to the oscillating end of the arm 5, and the boom 4 is connected to the first boom on the base end side. A boom cylinder that drives the boom 4 by connecting the third boom 4C on the distal end side via a second boom 4B forming a parallel quadruple link to the 4A, so that the bucket 6 can be translated in the horizontal direction. 7, an arm cylinder 8 for driving the arm 5, a bucket cylinder 9 for driving the bucket 6, and an offset cylinder 1 for driving the third boom 4C laterally with respect to the first boom 4A via the second boom 4B.
0 each. The dozer device B includes a dozer 11 supported on the side of the crawler traveling device 1 so as to be vertically swingable around an axis in a lateral posture, and a dozer cylinder 12 for driving the dozer 11 in a vertical direction.

As shown in FIGS. 1 and 2, inside the steering cabin C, the backhoe apparatus A is restored to a neutral position in a non-operating state so as to operate the backhoe apparatus A with respect to the front position of the driver's seat 13. A pair of operation levers 14 and 15 operable in the cross direction in the front-rear direction and the left-right direction is provided. A pedal 16 which is urged to return to a neutral posture in a non-operating state and is operable in the left-right direction is provided on the step surface. Have. The right operating lever 15 operates the boom 4 by operating in the front-rear direction, the bucket 6 operates by operating in the left-right direction, and the arm 5 operates by operating the bucket in the left-right direction. The turning table 2 is turned by a left-right operation, and the tip of the boom 4 is offset by a left-right stepping operation of a pedal 16.

As shown in FIG. 2, potentiometers 17, 18, and 19, which are linked with left and right operation levers 14, 15 to measure the operation directions and operation amounts of the levers 14, 15 in the front-rear direction and the left-right direction, respectively. , 20 and a potentiometer 21 which works with the pedal 16 to measure the operation amount of the pedal 16 in the left-right direction. As shown in the figure, signals from the potentiometers 17, 18, 19, 20, 21 are input, and the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the offset cylinder 10, the turning motor 3 (these are hydraulic actuators). Solenoid valves 7V, 8V, 9V,
The control device 22 outputs a drive signal to 10 V and 3 V (these are collectively referred to as solenoid valves V). The control device 22 has a built-in microprocessor (not shown) and increases the opening of the solenoid valve V so as to increase the drive speed of the hydraulic actuator as the operation amount of the operation levers 14, 15 or the pedal 16 increases. The solenoid valve V is set in proportion to the current value so that the larger the value of the current flowing through the solenoid S, the larger the opening is, and the supply and discharge of a larger amount of hydraulic oil is enabled. The electromagnetic proportional type is configured to change.

The control unit 22 can be schematically represented as shown in FIG. 3, and a control unit D having a microprocessor is provided inside the control unit 22, and the control unit D
And a feedback means F for converting a current value supplied to the electromagnetic solenoid S into a voltage value and feeding it back to the control unit, based on a signal from the control unit. . It should be noted that FIG.
Although only a control system for one electromagnetic solenoid S is shown, a control system of the same configuration for the electromagnetic solenoid S is provided inside the control device 22.

The current adjusting means E comprises a power transistor 23 driven by an intermittent signal from the control unit, and supplies a current from the power transistor 23 to an electromagnetic solenoid S of the solenoid valve V via a resistor R. (Energized), and an electric power system is formed to pass the current from the electromagnetic solenoid S to the body (ground position) of the vehicle body. The feedback means F is a power transistor 2 in the resistor R.
A differential amplifier 25 is provided that transmits a potential difference between the terminal on the third side and the terminal on the electromagnetic solenoid S via a voltage dividing circuit 24 (an example of a voltage applying unit). As shown in FIG. 4, the electromagnetic solenoid S of the electromagnetic valve V has a metallic casing 26 bolted to the main body of the electromagnetic valve V, and a spool of the main body of the electromagnetic valve V is provided inside the casing 26. VS
And a coil 28 for operating the plunger 27. One terminal 28A of the coil 28 extends to the outside of the casing, and the other terminal 28B is connected to the casing 26. The body is energized (body earthed).

The control unit includes the potentiometer 1
Input system from 7, 18, 19, 20, 21 (not shown)
And an output system for outputting an intermittent signal to the power transistor 23 and an input system for inputting a signal from the feedback means F.
The duty ratio (duty cycle) of the intermittent signal from the output system is adjusted so that the current of the target current value (corresponding to the target opening of the solenoid valve V) set in accordance with the operation amount of the solenoid valve flows through the solenoid S. And a control operation for adjusting the duty ratio of the intermittent signal based on a signal from the feedback unit F to obtain a target current value. The potentiometers 17, 18, 19, 2 are provided inside the control unit.
An A / D converter (not shown) for digitizing a voltage signal input to the input system from 0 and 21 and the input system from the feedback means F is provided.

As shown in FIG. 1, a voltage of 12 volts is applied to the differential amplifier 25 and the power transistor 23 via a terminal 29. Further, by applying a voltage of 5 volts to the voltage dividing circuit 24 via the terminal 30, a bias voltage serving as a reference of a signal voltage acting on the differential amplifier 25 is obtained from a voltage value between both terminals of the resistor R. It has been set. This bias voltage raises the voltage value to the input system of the differential amplifier 25, that is, what is called a pull-up voltage. When an intermittent current is supplied to the electromagnetic solenoid S as in this configuration, the bias voltage is intermittent. When switching from the energized state (ON state) to the cut-off state (OFF state) within a short time during the supply of current, a counter electromotive force is generated in the electromagnetic solenoid S and the resistor R
The input voltage of the differential amplifier 25 is maintained at a positive potential even if the voltage between both ends falls to a negative potential, so that the value of the current flowing through the electromagnetic solenoid S can be accurately grasped by the back electromotive force.

Since the control device 22 is configured as described above, for example, when the right operation lever 15 is operated from the neutral position by a predetermined amount in the front-rear direction, this operation amount is measured by the potentiometer 19 and The control unit D inside the control device 22 sets a target current value corresponding to the operation amount of the operation lever 15 based on a signal from the potentiometer 19, and intermittently sets a preset duty ratio to obtain the target current value. The signal is output to the power transistor 23. Next, when the power transistor 23 is driven, a current is supplied to the electromagnetic solenoid S of the solenoid valve 7V via the resistor R, but if the voltage of the power supply (not shown) is reduced, If the target current value cannot be obtained and the voltage of the power supply is higher than the expected voltage, a current higher than the target current value will be supplied. By amplifying the potential difference generated in direct proportion to the supplied current value by the differential amplifier 25 and feeding it back to the control unit D, the current value actually supplied in the control unit D can be accurately grasped. As a result, when the voltage difference between both ends of the resistor R is deviated from the value corresponding to the target current to a lower side, the duty ratio of the intermittent signal for the electromagnetic solenoid S of the solenoid valve 7V is adjusted to be larger, and conversely. Both resistors R If the voltage difference is higher than the value corresponding to the target current, the duty ratio of the intermittent signal to the electromagnetic solenoid S of the solenoid valve 7V is adjusted to a smaller value, so that the appropriate The boom cylinder 7 is operated at a low speed at a low speed. Moreover, in this configuration, the control of the solenoid valve V is possible only by wiring a power cable from the control device 22 to the solenoid S of the solenoid valve V, so that the wiring can be easily performed when the backhoe is manufactured.

[Other Embodiments] In addition to the above-described embodiment, the present invention provides a valve for controlling a hydraulic actuator in the form of a pilot pressure-operated valve as in, for example, the publications described in the prior art. The present invention can also be applied to a configuration in which a hydraulic actuator is driven by controlling this pilot pressure with an electromagnetic proportional type electromagnetic valve.

[0021]

Accordingly, the control device for measuring the value of the current supplied to the electromagnetic solenoid and adjusting the opening of the solenoid valve is configured with a small number of parts and can be easily assembled. 1). In addition, the value of the current flowing through the electromagnetic solenoid can be accurately measured (claim 2). Even when a counter electromotive force is generated when an intermittent current flows to the electromagnetic solenoid, the electromagnetic solenoid including this counter electromotive force is included in the electromagnetic solenoid. The value of the flowing current can be accurately measured to control the solenoid valve with high accuracy (claim 3).

[Brief description of the drawings]

FIG. 1 is an overall side view of a backhoe.

FIG. 2 is a block circuit diagram of a control system.

FIG. 3 is an electric circuit diagram of a feedback unit.

FIG. 4 is a partially cutaway side view of a solenoid valve.

[Explanation of symbols]

 24 Voltage applying means E Current adjusting means F Feedback means R Resistor S Electromagnetic solenoid V Solenoid valve

Claims (3)

[Claims] An electromagnetic valve whose opening is adjusted by a current value supplied to an electromagnetic solenoid is provided, and a target opening is obtained by controlling a current value supplied to the electromagnetic valve. A control device for an electromagnetic valve, wherein a resistor is interposed in series in a conductive system between a current adjusting means for adjusting a current value supplied to the electromagnetic solenoid and the electromagnetic solenoid, and a voltage signal is generated by the resistor. A control device for an electromagnetic valve, comprising a feedback unit for feeding back the converted signal. 2. The feedback means is of a differential type for obtaining a current value supplied to an electromagnetic solenoid based on a potential difference between a terminal on a current adjusting means side and a terminal on an electromagnetic solenoid side in the resistor. The control device for a solenoid valve according to claim 1, wherein 3. The current adjusting means supplies an intermittent current to an electromagnetic solenoid, and adjusts a supply current value to the electromagnetic solenoid by adjusting a duty ratio of the intermittent current. 3. The electromagnetic valve control device according to claim 2, further comprising voltage applying means for applying a bias voltage to a signal system from a terminal on a current adjusting means side and a terminal on an electromagnetic solenoid side.