JPS6053204A - Hydraulic cylinder control device - Google Patents

Abstract

PURPOSE:To raise the controlling precision and operational easiness by raising the input voltage suddenly at around the maximum tilt angle of a control lever. CONSTITUTION:A comparator 73 and an electric current I2 setter 70 are set in the controller part 7. When the potentiometer output reaches around the maximum tilt angle of a lever, the comparator 73 is turned on, an analogue switch 75 is closed, and an output of the electric current I2 setter 74 is input into an adding circuit 63. In this way, the controlling precision can be raised because the input voltage rises suddenly at around the maximum tilt angle of the control lever, and an insensible area around there can be reduced while a plunger is full-stroked. Moreover, as moving speed of a work table can be set to be low within the determined range of an effective tilt angle of the lever, the controller can be operated easily within the range.

Description

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

2. Description of the Related Art Conventionally, as a device for controlling a hydraulic actuator using an electromagnetic proportional valve, for example, a control device for an aerial work vehicle as shown in FIG. 1 has been proposed by the present applicant in Japanese Patent Application No. 55-1223.

That is, it has an upper tower 3 and a lower tower 4, each of which has a workbench 2 for the worker 1 scattered at its tip, and these towers can be raised and lowered appropriately using hydraulic cylinders 5 and 6. The workbench 2 can be freely moved up and down.

Both hydraulic cylinders 5 or 6 are connected to a controller section 7 and a hydraulic pulp 8 responsive to the controller section 7 as shown in FIG.
The extension and contraction operation is freely controlled by the control lever 9 through the above example.

To explain this now, the hydraulic pulp 8 is composed of: 2- a switching valve 21 and a position limiter 39; The controller section 't proportionally increases or decreases the current to the electromagnetic proportional solenoids to and tt provided in the position limiter 39 in accordance with the tilt angle of the control lever 9.

For example, when the control lever 9 is tilted to the right from the neutral position, the current to the electromagnetic proportional solenoid 10 gradually increases from zero according to the tilt angle, except for a dead zone described below. Conversely, when the lid is tilted to the left from the neutral position, the current to the electromagnetic proportional solenoid 11 gradually increases from zero.

On the other hand, the position limiter 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 a pilot oil pressure supply passage 16, an orifice 17.
Pilot hydraulic pressure is introduced through steps 18 and the like.

and an outlet 14a of each pressure chamber 14.15.

The cross-sectional area of 15a is the aforementioned electromagnetic proportional solenoid 10°1
1, the solenoid plunger 10b moves up and down.

11b) can be freely increased or decreased by vertical movement of 10a and lla.

For example, current flows through the electromagnetic proportional solenoid 10)
When 10a moves upward, the cross-sectional area of outlet 14a changes to outlet 15a.
, and a differential pressure is created in both pressure chambers 14 and 15.

As a result, the double-acting piston 13 moves rightward and stops at a position where this moving force and the elastic force of the spring 440 are balanced.

The amount of movement at this time, that is, the amount of stroke of the double-acting piston 13 increases in proportion to the current flowing through the electromagnetic proportional solenoid 10.

Conversely, current flows through the electromagnetic proportional solenoid 11 and the poppet I
When la moves upward, the double-acting piston 13 moves to the left.

In this way, the double-acting piston 13 moves left and right with a stroke amount that corresponds to the current flowing through the electromagnetic proportional solenoids 10 and 11, that is, the tilt angle 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.
a is connected, and this switching valve 21 is connected to the double acting piston 13.
That is, depending on the amount of displacement of the plunger 21a, hydraulic oil is sent from the hydraulic pump (not shown) to the hydraulic cylinder 5 (6), and hydraulic oil is returned from the hydraulic cylinder 5 (6) to the oil tank (not shown). and hydraulic cylinder 5 (
6) Regulate the quantitative ratio of the hydraulic oil that bypasses and returns to the hydraulic tank.

As a result of such operation of the hydraulic pulp 8, 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 solenoid 11.

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 current to the electromagnetic solenoid 10 is increased by tilting it to the right, the amount of hydraulic oil also increases, the hydraulic cylinder 5 (6) is extended, and the upper tower 3 (or lower tower
) gets up.

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 in the change in the flow rate of the hydraulic oil to the hydraulic cylinder 5 (6) with respect to the stroke of the plunger 21a 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 plunger 21a has stroked approximately 2.5 ts+ from the neutral position.

Therefore, even if the control lever 9 is tilted from the neutral position, the hydraulic cylinder 5 (6) cannot extend or retract until the plunger 21a is displaced beyond the neutral dead zone.

Therefore, the hydraulic cylinder 5 (6) generated in this way
In order to narrow the unnecessary dead band width of the control lever 9 with respect to the expansion and contraction operation of the hydraulic cylinder, that is, the amount of hydraulic oil supplied to the hydraulic cylinder, and to ensure stability in the neutral position, there is a gap between the plunger 21a and the double acting piston 13. has plunger 2
A stepped portion 40 formed by coupling 1a and the connecting rod 43 and a flange portion 4 of the connecting rod 43
A spring 44 is provided on the outer periphery of the small diameter portion formed by 1.

This spring 44 has a stepped portion 40 and a flange portion 4.
When the plunger 21a is displaced leftward from the neutral position, for example, 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 affected by the displacement force, and while the holder 46 is stopped by the stop surface 4B, the holder 45 is stopped by the stop surface 4B. is displaced, so
Similarly, the spring 44 contracts in proportion to its displacement force.

At this time, in order to obtain stability in the neutral position, the spring 44 is sandwiched between the holders 45 and 46 with a predetermined initial load. The plunger 42 stably holds its neutral position until the differential pressure exceeds this initial load.

However, the dead band width is due to the initial load of the plunger 2.
Since the dead zone until the control lever 1a starts to move and the dead zone until the oil starts flowing after it starts moving, it may be too large than necessary, so in order to reduce the width of the dead zone of the control lever, the fourth As shown in the figure, the response characteristics of electromagnetic proportional solenoids 10 and 11 to the tilting movement of the control lever 9 are changed in the controller section 7.

That is, in FIG. 4, 50.51 is a potentiometer (sliding resistance) connected to the control lever 9, and 7A
, 7B is a controller section, and 10.degree. 11 is an electromagnetic proportional solenoid interposed in the hydraulic pulp 8.

The potentiometers 50 and 51 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 controller section 7A responds to the tilt angle of the control lever 9. Only the current flowing to the electromagnetic proportional solenoid 10 gradually increases from zero.

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

Since the controller sections 7A and 7B are configured in exactly the same way, only the controller section 7B will be shown in detail in the drawings and will be specifically explained.

56 to 58 are comparators, and the comparator 56 is a buffer circuit 54.
When the output of the potentiometer 51 changes from 0, it turns on and makes the analog switch 55 conductive.

The comparator 57 turns on when the potentiometer output exceeds the neutral dead band, turns on the analog switch 61, and inputs the output of the current 1 setter 59 to the adder circuit 63.

The comparator 58 has the same set value -9- as the comparator 56, for example.
.

When turned on, the analog switch 62 is made conductive and the dither signal from the oscillation circuit 60 is synthesized into the adder circuit 63.

The adder circuit 63 adds the above-mentioned additional current I to the potentiometer output via the buffer circuit 54, corrects it so that a rise after the neutral dead zone is obtained, and applies this to the amplifier 64.
The drive circuit 651 (input) is made up of power transistors and the like.

Therefore, the drive circuit 65 outputs a drive current corresponding to the operation amount of the control lever 9 plus a correction value to the electromagnetic proportional solenoid 11 .

FIG. 5 shows the output current of the controller section 7 with respect to the tilt angle of the control lever 9. However, the dither signal is omitted.

As can be seen from the figure, when the control lever 9 passes the intentional dead zone A provided for safety, the output current I
21a rose sharply, causing
When stroked to the -1n- upper limit of the neutral dead zone of the switching valve 21, the control current value is increased proportionally according to the tilting angle of the control lever 9.
This increases the pulp flow rate.

In this way, the input voltage (control lever tilt angle)
As a result, the neutral dead zone A of the control lever 9 is reduced.

By the way, if we focus on the control range where the flow rate from the hydraulic pulp 8 is maximum, we can find the control current value that provides the maximum flow rate.
, changes due to processing errors of pulp components, so
It is necessary to take this variation into consideration and set it large in advance, and if this is done, the required dead zone width in the maximum flow rate region will become large.

Due to machining errors in the picks and pulp components, even when controlling the current value, the plunger may not stop by a predetermined amount and the maximum flow rate cannot be obtained. From I3 to thicker I4 (I4 >
Is), the rate of increase in output current increases as shown in FIG. 5 (4) in normal pulp. For this reason, the rate of increase in the flow rate from the hydraulic pulp 8 also changes from the solid line in Figure 5 CB) to the broken line, and the lever tilting angle at which the maximum flow rate occurs moves to the left from θ2, and θS (θ, <θ,)
becomes.

This means that the dead zone given between the lever maximum tilting angle θmax expands from B to C, which narrows the range of effective control angle of the control lever, and as a result, the unit tilting angle The accuracy of pulp control was reduced.

In order to solve this problem, the present invention suddenly increases the input voltage near the maximum tilt angle of the control lever to obtain the output current necessary for a full pulp stroke, thereby reducing the dead band. It is an object of the present invention to provide a hydraulic cylinder control device that achieves reduction and improvement of control accuracy accordingly.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 6, the comparator 73 is turned on when the potentiometer output reaches around the maximum lever tilt angle.
Make the analog switch 75 conductive and do the electrical work! Setting device 70
The output is input to the adder circuit 63.

Since the other parts are the same as those in FIG. 4, the same parts are given the same reference numerals and the explanation will be omitted.

Note that this example is the controller section 7A in FIG.

7B have exactly the same configuration, one of them is used in common to simplify the circuit.

That is, 70 is a potentiometer that is linked to the control lever 9, and the potentiometer slider is set so that it is at the center origin at the neutral point of the lever.Therefore, even if the lever 9 is tilted to the left or right, it is proportional to the angle. output.

Reference numeral 71 denotes a direction discrimination circuit that compares the output of the potentiometer 70 with a reference voltage at a neutral point to discriminate the left/right operation direction of the control lever 9.Based on the discrimination result, a solenoid selection circuit (relay) 76, which will be described later, is switched, and the electromagnetic A control current from the drive circuit 65 is supplied to the proportional solenoid 10 or 11.

72 is an absolute value circuit, which generates an absolute output corresponding only to the angle 13- (deviation) of the output of the potentiometer 70 inputted through the buffer circuit 54, even if the output is switched in any direction from the neutral point. do.

The adder circuit 63 adds the above-mentioned additional currents I, , I, to the potentiometer absolute output from the absolute value circuit 72,
It is corrected so as to obtain the start-up after the neutral dead zone and the start-up near the maximum tilt angle, and is powered up by an amplifier 64 and further inputted to a drive circuit 65 composed of power transistors and the like.

Therefore, regardless of the direction in which the control lever 9 is operated, the output of the drive circuit 65 is the output corresponding only to the amount of operation of the control lever 9 plus a correction value.

A selection circuit 76 selects which electromagnetic proportional solenoid 10 or 11 is to be driven by this output.

The selection circuit 76 is switched by the output of the direction determination circuit 71 which determines the direction in which the control lever 9 is tilted, and thereby a drive current is supplied to either the electromagnetic proportional solenoid 10 or 11.

Therefore, only one drive current controller is required, and the circuit is simplified.

With the above configuration, until the tilting angle of the control lever 9 reaches θ, which is just before the maximum tilting angle θmax, the potentiometer output is
, only the output current value ■ of the setting device 59 is added, but when θ, which is just before the maximum tilt angle θmax, is reached and the comparator 73 is turned on, the output current value 11 is sufficiently increased compared to the output current value 11. Since the large output current value (2) is also added, the output current (2) rises rapidly at that point, and the current value (2) required to make the full stroke of the plunger 21a including the error amount is instantaneously obtained.

As a result, as shown by the broken line in FIG. 5 (3), conventionally, as an input to the adder circuit 63, a control current I having a slope proportional to the composite value of the potentiometer output and the output of the setting device 11 exceeds s Is. Since the output current had to be increased proportionally up to 0.4, the angle of the control lever 〇 had to exist as a dead zone when the angle was above the predetermined value 03. It is possible to maintain an effective control angle up to a larger value θ, and in other words, the dead zone can be made that much narrower.

In this way, by reducing the dead zone near the neutral position and maximum tilting angle of the control lever 9, the effective control angle range expands by that amount9, thereby improving the control accuracy of the unit lever tilting angle. It also becomes possible.

By the way, in the effective control angle range of the control lever 9, since the rate of increase in the output current I with respect to the lever tilting angle is constant, the rate of increase in the flow rate with respect to the lever tilting angle is also constant.

In this case, the rate of increase in the flow rate determines the moving speed of the work platform 2 on which the worker 1 stands, and if the tilting operation is performed by an inexperienced operator, the moving speed at the beginning of the movement will be too fast, causing the operator to The operator at the stand may feel a sense of fear.

In other words, since speed control at startup requires fine operations, it is necessary to become proficient in the operations.

Therefore, in order to easily perform fine operations without having to become familiar with the operation, a circuit is provided in which the increase rate of the output current value is changed at a predetermined tilt angle in which the control lever 9 is within the effective control angle range, as shown in FIG. Then, the analog switch 55 and the addition circuit 6
3.

This circuit is composed of variable resistors 80 and 82 and a level shifter 81. The level shifter 81 and variable resistor 82 are connected in series, and the variable resistor 80 is connected in parallel.

The variable resistor 80.82 has an increase rate of output current I of 01°Gt.
(Specifically, Gt and Gt are the ratio of the output current I and the input voltage ■, but since the input voltage V corresponds to the lever tilting angle, it will be explained here as the ratio of the output current and the lever tilting angle. ) are respectively set to predetermined values.

The level shifter 81 becomes conductive when a potentiometer output corresponding to a predetermined lever tilt angle θ4 (G1<G4<θt)K in the effective control angle range is reached.

Nao, G4 is the maximum tilt angle θma of control lever 9
It is set within the range of 50 to 70% of x, and in this example θm
When ax is 30 degrees, 20'', which is 2/3 of that, is set as 04.

Therefore, the output current is G as shown in Figure 7 (4).
Up to 4, the variable resistor 80 increases at an increasing rate G, and G
After 4, G2 is added by variable resistor 82, 10G.
, increases with .

Therefore, as shown in Figure 7), the rate of increase in the flow rate changes from small to large with the flow rate Qa being Sakai, and Qa is 2 of the total flow rate.
It is set within the range of 5 to 55%, and in this example is set to 50%.

In other words, when the lever tilt angle is 04 or less, the increase rate of the flow rate is set to be smaller than before, and in this range, the movement speed of the workbench is slow, and the speed control at startup is easily performed. .

In this example, the range in which the increase rate of the flow rate is set to be small is from G1 to θ, but the setting range can be freely set as long as the lever tilt angle is between G1 and 02.

As described above, according to the present invention, it is possible to reliably fully stroke the plunger (hydraulic pulp) near the maximum tilting angle of the control lever while reducing the dead zone in the vicinity, and as a result, the dead zone of the control lever can be reduced. Control accuracy can also be improved by increasing the effective tilt angle. Furthermore, since the movement speed of the workbench can be set small within a predetermined range of the effective tilting angle of the lever, it is also possible to obtain the effect of improving operability within this range.

(Additional Relationship) The present invention relates to the invention of the hydraulic cylinder control amount disclosed in Japanese Patent Application No. 56-58021, and an invention in which all of its components are the main components of the present invention, and which achieves the same object. O that satisfies the requirements for additional patents as stipulated in Article 31, Item 1 of the Patent Law.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the aerial work vehicle, Figure 2 is a sectional view of the main part of the hydraulic pulp that controls the hydraulic cylinder in Figure 1, and Figure 3 is a schematic diagram of the aerial work vehicle.
The figure is a characteristic diagram showing the operation of the hydraulic pulp in Figure 2, Figure 4 is a circuit diagram of the controller section that controls this hydraulic pulp, and Figure 5 (4), ■) is the output current and operation to the hydraulic cylinder. FIG. 3 is a characteristic diagram showing the flow rate of oil. Figure 6 is a circuit diagram of the controller section of the present invention, Figure 7 (4), @
0 is a characteristic diagram showing the output current and the flow rate of hydraulic oil to the hydraulic cylinder with respect to the tilting angle of the control lever. 0 3... Upper tower, 4... Lower tower, 5, 6... Hydraulic cylinder, 7.7A, 7B... Controller section, 8... Hydraulic pulp, 9... Control lever, 10.11.
... Electromagnetic proportional solenoid, 10a, lla... Hohet, 12... Double acting cylinder, 13... Double acting piston, 14° 15... Pressure chamber, 14a, 15a... Pressure chamber outlet, 16...Pilot oil pressure supply passage, 17.
18... Orifice, 21... Switching valve, 21a...
・Plunger 39...Position limiter, 50, 51
, 70... Potentiometer, s5, 61.7s...
・Analog switch, 56, 57.73... Comparator,
59...11 setting device, 63...addition circuit, 64...
- Amplifier circuit, 65... Drive circuit, 80.82... Variable resistor, 81... Level shifter. Patent applicant Kayaba Kogyo Co., Ltd.

Claims (1)

[Claims] A passage provided with an orifice for introducing pilot oil into two pressure chambers partitioned by the double-acting piston, and a double-acting piston by increasing or decreasing the exit cross-sectional area of the pilot oil from both pressure chambers. Hydraulic pulp has two electromagnetic proportional solenoids that are displaced, and has a dead band that adjusts the flow rate of hydraulic oil to the hydraulic cylinder according to the displacement of the double-acting piston, and a hydraulic pulp that has two electromagnetic proportional solenoids that are displaced by tilting the control lever. In a control device equipped with a controller unit that controls the increase/decrease of the drive current of the control panel, the drive current of both electromagnetic proportional solenoids is added according to the width of the dead zone of the hydraulic pulp over a predetermined range when the control panel is tilted from the neutral position. A correction circuit, a circuit that adds a rising current to further stroke the hydraulic pulp to a full stroke in the maximum tilting angle range, and an increase in output current at a predetermined tilting angle in the effective control angle range of the control lever -l -07 A hydraulic cylinder control device characterized in that a controller section is equipped with a circuit that changes a ratio.