JPS58142006A - Controller of solenoid proportional valve - Google Patents

Abstract

PURPOSE:To simplify a circuit, by deciding the tilting direction of a control lever through an output of a potentiometer and supplying an amplification output to a solenoid proportional valve on the basis of a decision result. CONSTITUTION:A poentiometer absolute output from an absolute value circuit 63 is added with a further current in an adder circuit 75 and powered up by an amplifier 76 further input to a driver circuit 77 constituted by a power transistor or the like. A selector circuit 78 is switched by an output of a direction decision circuit 62 deciding the tilting direction of a control lever to feed a driving current to either a solenoid proportional valve solenoid 10 or 11. As the above result, only one system is required for an amplifier circuit of the driver current to simplify the circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device in a hydraulic drive circuit using an electromagnetic proportional valve.

2. Description of the Related Art Conventionally, as an example of controlling a hydraulic actuator using an electromagnetic proportional valve, a control system for an aerial work vehicle as shown in FIG. 1 has been proposed by the present applicant in Japanese Patent Application No. 58021/1983.

That is, it has an upper tower 3 and a lower tower 4, each of which has a workbench 2 for the worker 1 attached to its tip, and these towers are raised and lowered appropriately using a hydraulic cylinder 5.6, so that the work can be done easily. The table 2 can be freely moved up and down.

Both hydraulic cylinders 5 or 6 are connected to a controller section 7 and a hydraulic valve 8 responsive to the controller section 7 as shown in FIG.
The expansion and contraction operation can be freely controlled by the control lever 9 via the control lever 9.

To explain this now, the hydraulic valve 8 is the switching valve 2.
1 and an I position limiter 39. The controller section 7 controls the solenoid 10 of the electromagnetic proportional valve of the 4-position limiter 39 according to the tilt angle of the control lever 9.
11 proportionally.

For example, when the control lever 9 is tilted to the right from the neutral position, the current to the electromagnetic proportional solenoid 1o gradually increases from zero in accordance with the tilt angle, except for a dead zone described below. Conversely, when tilting to the left from the neutral position, the current to the electromagnetic proportional valve solenoid 11 gradually increases from zero.

On the other hand, the position lever 39 has a mutually symmetrical annular pressure chamber 14.15 partitioned by the double-acting piston 13 inside the double-acting cylinder 12, and both pressure chambers 14.1
5 has no.4 pilot oil pressure supply passage 16 and oriais 17.
．． 18 etc., /4 pilot hydraulic pressure was introduced.

and an outlet 14m for each pressure chamber 14.15.

The cross-sectional area of 151 is the same as that of the electromagnetic proportional valve solenoid 10.
It can be freely increased or decreased by vertical movement of each poppet 10a, 11m linked with 11.

For example, when the electromagnetic proportional valve solenoid IOK current flows and the -(t 101 moves upward), the cross-section 11° area of the outlet 14m decreases relative to the outlet 15m, and a differential pressure is created in both pressure chambers 14.15. arise.

As a result, the double-acting piston 13 moves rightward and stops at a position where this moving force and the elastic edge of the spring 44 are balanced.

The amount of movement at this time, that is, the amount of stroke of the double-acting piston 13 increases proportionally in accordance with the current flowing through the electromagnetic proportional valve solenoid IO.

Conversely, when a current flows through the electromagnetic proportional valve solenoid 11 and the poppet lla moves upward, the double-acting piston 13 moves to the left.

In this way, the double-acting piston moves left and right with a stroke amount corresponding to the current flowing through the solenoid 10.11 of the 13-manufactured electromagnetic proportional valve, that is, the tilt angle 11C of the control lever 9.

Further, the plunger 21 of the switching valve 21 is connected to the double-acting piston 13 via a connecting rod 43 that moves integrally with the double-acting piston 13.
m is connected, and this switching valve 21 is connected to the double acting piston 1.
3. In other words, depending on the position of the plunger 21&, the oil pressure f
Hydraulic oil is sent from the pump (not shown) to the hydraulic cylinder 5 (6), hydraulic oil is returned from the hydraulic cylinder 5 (6) to the oil tank (not shown), and hydraulic oil is sent from the hydraulic cylinder 5 (6) to the hydraulic cylinder 5 (not shown).
(6) is used as an analogy to regulate the quantitative ratio of the hydraulic fluid that returns to the hydraulic pump.

As a result of such operation of the hydraulic pulp 8, for example, the hydraulic cylinder 5
(6) The flow rate of hydraulic oil in the extension direction increases, and conversely, the flow rate of hydraulic oil in the contraction direction increases in accordance with the current flowing through the electromagnetic proportional valve Renoid IIK.

On the other hand, since the stroke position of the hydraulic cylinder 5 (6), that is, the elevation angle of the upper tower 3 (or lower tower 4) is adjusted by the amount of hydraulic oil supplied, for example, the control lever 9 is moved to the neutral position. When the electric current to the electromagnetic proportional valve solenoid 10 is increased by tilting it to the right, the amount of hydraulic oil also increases, the hydraulic cylinder 5 (6) extends, and the upper tower 3 (or lower tower 4) rises.

Conversely, if the control lever 9 is tilted to the left, the upper tower 3 (or lower tower 4) will fall.

By the way, as shown in FIG. 3, for example, the aforementioned switching valve 21 has a neutral dead zone A when the flow rate of the hydraulic oil to the hydraulic cylinder 5 (6) changes with respect to the stroke of the granger 21m from the neutral position.

That is, in this case, the switching valve 21 can change the flow rate of the hydraulic oil only after the granger 21m has stroked approximately 2.5 m or more from the neutral position.

Therefore, even if the control lever 9 is tilted from the neutral position, the hydraulic cylinder 5 (6) cannot be extended or retracted until the granger 21m is displaced beyond the neutral dead zone.

Therefore, the hydraulic cylinder 5 (6) generated in this way
The plunger 2
1a and the double-acting piston 13 is provided with an outer WJK spring 44 having a small diameter portion formed by a stepped portion 4o formed by coupling the plunger 21m and the connecting rod 43 and a flange portion 41 of the connecting rod 43. There is.

This spring 44 is connected to the stepped portion 40. Flange part 4
The plunger 21 is held between stepped cylindrical holders 45 and 46 which are slidably fitted into the holder 9, and when the plunger 21 is displaced from the neutral position to the left, the holder 45 moves to the stop surface 4.
7, whereas the holder 46 is displaced in conjunction with the flange portion 41, the spring 44 is compressed by an amount proportional to the displacement force.

Conversely, when the plunger 21m is displaced rightward from the neutral position, the holder 46 is stopped by the stop surface 48, but the holder 45 is now displaced, so the spring 44 is similarly activated in proportion to the displacement force. It shrinks.

At this time, in order to obtain stability in the neutral position, the spring 44 is held between the holders 45 and 46 with a predetermined initial load, and therefore the difference in pilot oil acting on the double-acting piston 13 is The red plunger 21m stably maintains its neutral position until the pressure exceeds this initial load.

However, the dead band width is due to the initial load of the plunger 2.
Since it corresponds to the sum of the dead zone until the control lever starts moving and the dead zone after it starts moving until the oil starts flowing, it may become too large than necessary. Therefore, in order to reduce the width of the dead zone of the control lever, the width of the dead zone shown in Fig. 4 is In this manner, the response characteristics of the electric proportional valve solenoids 10 and 11 to the tilting movement of the control lever 9 are changed in the controller section 7.

In other words, in Figure 4, 31.32 is the control Ok L
/ Sliding resistance (potentiometer) connected to bar 9
, 33 and 34 are amplifier circuits, and 10 and 11 are electromagnetic proportional valve solenoids interposed in the hydraulic valve 8.

The sliding resistors 31 and 32 are connected to the control lever 9 so as to exhibit resistance changes independently of each other. For example, when the control lever 9 is tilted to the right from the neutral position, the amplification circuit 33 changes in resistance. Only the current to the electromagnetic proportional valve solenoid 10 gradually increases from zero depending on the angle.

Conversely, when tilting to the left from the neutral position, only the current to the electromagnetic proportional valve solenoid 11 gradually increases from zero.

Since the amplifier circuits 33 and 34 are constructed in exactly the same way, only the amplifier circuit 34 will be shown in detail in the drawings and will be specifically explained.

The sliding terminal voltage signal jla of the sliding resistor 32 changes proportionally according to the tilt angle of the control lever 9, and the amplifier 35
, transistors 36 and 37, and then supplied to the electromagnetic proportional valve solenoid 11 as a current signal.

At this time, in order to quickly stroke the hydraulic valve 80 and the no-range gear 21& to the upper limit of the neutral dead zone of the switching valve 21, in order to narrow the dead zone width of the control lever 9 as described above, the tilt angle of the control lever 9 is adjusted to a predetermined degree. After that, when the intentional dead zone for safety is exceeded, the controller 38 adjusts the sliding resistance 32 based on the magnitude relationship between the sliding terminal voltage signal and the predetermined reference voltage signal B. A predetermined additional voltage is supplied to the amplifier 35 in addition to the current supplied to the electromagnetic proportional valve solenoid 11, and the predetermined current is forcibly added to correct the current flowing to the electromagnetic proportional valve solenoid 11.

Then, after crossing the neutral dead zone, Control Leno 4
The plunger 21 is
1 stroke, solenoid proportional valve solenoid Fil
Variable resistor VR- for adjusting the amplification factor
1 to a predetermined value.

Note that the width of the dead zone of the control lever 9, which is intended to prevent valve operation due to careless contact, etc., can be freely adjusted by increasing or decreasing the value of the reference voltage signal B via the variable resistor VR-2. It is possible to do so.

Also, the switching valve 2 with respect to the stroke of the plunger 21 &
If the neutral dead zone of 1 is large, the added voltage may be correspondingly increased by the variable resistor VR-3 to further increase the added current to the electromagnetic proportional valve solenoid 11. FIG. 5 shows the output current of the controller section 7 with respect to the tilt angle of the control lever 9.

As can be seen from the figure, when the control lever 9 passes the intentional dead zone provided for safety, the output current I suddenly rises to the current 11, and as a result, the sylanger 2
1m to the upper limit of the neutral dead zone of the switching valve 21, the control current value is increased proportionally according to the tilt angle of the control lever 9, and the valve flow rate is increased.

In this way, the input voltage (control lever tilt angle)
As a result, the neutral dead zone of the control lever 9 is reduced. Also, focusing on the control range where the flow rate from the hydraulic valve 8 is maximum, the control current (2) that provides the maximum flow rate changes due to processing errors of the pulp components, so if it is set large in advance in anticipation of the variation, The required dead band width in the maximum flow range increases.

In order to prevent such problems, input to the amplifier 35 in the maximum pulp flow rate range is necessary. The output value of the sliding resistor 32 is combined with the output E of the controller 50, and the solenoid excitation current I is generated in the maximum rotation angle range of the control lever 9.
Let the process rise rapidly from work to work.

The controller 41j-50 compares the output A of the sliding resistor 32 with a reference voltage signal set via the variable resistor VR-4, and outputs a voltage of /1 if the set value is exceeded.

This voltage value is adjusted to a predetermined value E using a variable resistor VR-5, and as shown in FIG. Add to input voltage A so that

In this way, by reducing the dead zone between the neutral position and the maximum tilt angle of the control lever 9, the effective control angle range expands by that amount.This improves the control accuracy of the unit lever tilt angle. is also possible.

However, in this case, since two amplifier circuits 33 and 34 having exactly the same configuration are provided, the circuit becomes complicated, and adjustment takes time and effort, resulting in high cost.

The present invention was proposed to solve this problem, and the direction of tilting of the control lever is determined by using the neutral point of the potentiometer (sliding resistance) as the origin and comparing the magnitude of the output of the potentiometer with a reference value. To provide a control device which simplifies the circuit by performing discrimination and amplification using a common circuit and selectively supplying the amplified output to an electromagnetic proportional valve based on the discrimination result. .

Hereinafter, an embodiment of the present invention will be described based on FIG. 6.

60 is an fbyllf potentiometer that is linked to the control lever 9, and is set so that the potentiometer slider is at the center origin at the neutral point of the lever, so that no matter which direction the lever 9 is tilted to the left or right, the output is proportional to the angle. issue.

61 is a buffer circuit, and 62 is a direction discrimination circuit that compares the output of the potentiometer 60 with a reference voltage at a neutral point to determine whether the control lever 9 is to be operated left or right.Based on the discrimination result, a solenoid selection circuit (relay), which will be described later, is provided. 7
8 and supplies the control current from the drive circuit 77 to the electromagnetic proportional valve solenoid 10 or ]l.

63 is an absolute value circuit, which generates an absolute output corresponding only to the angle (deviation) of the output of the 4 tensiometer 60 input via the buffer circuit 61, no matter which direction it switches from the neutral point. .

65 to 68 are comparators, and the comparator 65 is turned on when the output of the peak value circuit 63 changes from 0, and makes the analog switch 64 conductive.

The comparator 66 turns on when the output of the 4 tensiometer exceeds the neutral dead band, turns on the analog switch 72, and inputs the output of the current 11 setter 69 to the adder circuit 75.

The comparator 67 is turned on when the f-tensile meter output reaches around the maximum lever tilt angle, and the analog switch 73 is turned on.
is made conductive, and the output of the current value setter 70 is similarly inputted to the addition circuit 75.

For example, the comparator 68 is turned on with the same setting value as the comparator 65, and the analog switch 74 is made conductive to combine the day signal from the oscillation circuit 71 into the adder circuit 75.

The adder circuit 75 adds the above-mentioned additional current to the four tensiometer absolute outputs from the absolute value circuit 63, corrects it so that a rise after the neutral dead zone or a rise near the maximum tilt angle is obtained, and adds this to the amplifier 76. Then, the signal is input to a drive circuit 77 composed of an arm transistor and the like.

Therefore, irrespective of the direction in which the control lever 9 is operated, the output of the drive circuit 77 becomes the following by adding a correction value to the output corresponding only to the amount of operation.

A selection circuit F8 selects which electromagnetic proportional valve solenoid IO or 11 is to be driven by this output.

The selection circuit 78 is switched by the output of the direction determining circuit 62 which determines the direction in which the control lever 9 is tilted, and thereby a drive current is supplied to either the electromagnetic proportional valve solenoid 10 or 11.

As a result of the above, in the present invention, only one drive current amplification circuit is required, which significantly simplifies the circuit.

1 + Voltage settings for each comparator 65 to 68 and jump current 1
The level setting of l-Is can also be easily adjusted because there is only one amplifier circuit.

Furthermore, regarding the deviation (initial error) K between the control lever 9 and the potentiometer 1 meter distance 60, the expansion circuit 6
By changing the bias amount of 1, it can be easily set to -1.

As described above, according to the present invention, it is possible to simplify the control circuit and facilitate adjustment, and at the same time, there is an effect that costs can be reduced.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional aerial work vehicle, Figure 2 is a sectional view of the main part of the hydraulic valve that controls the hydraulic cylinder in Figure 1, and Figure 3 is a characteristic diagram showing the operation of the hydraulic valve in Figure 112. , FIG. 4 is a circuit diagram of a controller section that controls a hydraulic valve, and FIG. 5 is a diagram showing its operating characteristics. FIG. 6 is a block circuit diagram of the controller section of the present invention. 3-Upper tower, 4...Lower tower, 5.6...Hydraulic cylinder,
7...Controller section, 8...Hydraulic pressure flow, 9.
...Control lever, 10.11...Solenoid proportional valve solenoid, ]Oa, lla, jt'Pet, 12'
- Double-acting cylinder, 13-...Double-acting piston, 14.1...Pressure chamber, 14m, 15m...Pressure chamber outlet, 1
6. Main hydraulic pressure supply passage, 17, 18...
Orifice, 21...Switching valve %21&-...Plunger, 60--Potentiometer, 62...Discrimination circuit,
63...Absolute value circuit, 65-68...Comparator, 75
- Addition circuit, 77... Drive circuit, 78-... Selection circuit. Patent applicant Kayaba Kogyo Co., Ltd. Figure 3

Claims (1)

[Claims] In a control device that increases or decreases the control current of a corresponding electromagnetic proportional valve of two electromagnetic proportional valves according to the offset position of the control lever from the neutral point to the left or right, a potentiometer linked to the control lever; A circuit that compares the output of the potentiometer with a reference voltage at a neutral point to determine the lever tilting direction, a circuit that outputs only the absolute output according to the lever angle of the four tensiometers, and a circuit that amplifies this absolute output. A control device for an electromagnetic proportional valve, comprising a selection circuit that selectively supplies an amplified output to one of the electromagnetic proportional valves based on the output of the discrimination circuit.