JP2000275002A - Apparatus for controlling to switch stroke operation of hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly rewrite a reference voltage value of a proximity sensor even when a piston unstably moves in the vicinity of a stroke end. SOLUTION: Switching a stroke operation of two hydraulic cylinders is conducted by a command from a controller 15 on the basis of an ON/OFF signal of proximity sensors LS1 and LS2. ON-OFF judgment parts 221 and 222, and reference voltage-setting parts 231 and 232 are incorporated in the controller 15. The ON-OFF judgment parts 221 and 222 measure operating voltages of the proximity sensors LS1 and LS2 and generate a rewrite command to the opposite reference voltage-setting parts 232 and 231 when ON is turned to OFF. The reference voltage-setting parts 232 and 231 set fresh reference voltages on the basis of a voltage difference between the ON and OFF times and provides the voltages as a reference for a next ON-OFF judgment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stroke operation switching control device for controlling switching of a stroke operation of a piston in hydraulic oil (pressure oil) of a hydraulic cylinder.

[0002]

2. Description of the Related Art For example, in a high-viscosity fluid pump such as a concrete pump, two pistons of two main hydraulic cylinders are normally advanced and retracted alternately to connect two pistons to the pistons via rods. The fluid pressure feeding piston is alternately advanced and retracted, and when the fluid pressure feeding piston is advanced and the viscous fluid is pumped, the suction / discharge valve in the hopper is switched and the pressure oil supply / discharge line to the two main hydraulic cylinders is switched. However, the switching between the suction / discharge valve and the main hydraulic cylinder is performed after detecting that the piston of the main hydraulic cylinder has reached the forward stroke end.

As a method of detecting a piston position of a hydraulic cylinder such as a main hydraulic cylinder used in the above-mentioned high-viscosity fluid pump, there is a method of detecting the piston position by a detecting device integrally assembled with the hydraulic cylinder itself.

[0004] As a detection device integrated assembling type, a center pipe made of a non-magnetic material having a base end fixed to a head cover so as to reach the entire length of the cylinder is inserted into a rod through the piston at the axis of the hydraulic cylinder. Conventionally, a reed switch is disposed at a position corresponding to the rod-side stroke end of the center pipe, and the approach of a permanent magnet mounted on the piston is detected by the reed switch.

However, in the case of the above-mentioned reed switch system, not only the structure of the hydraulic cylinder becomes complicated, but also it is difficult to set the position of the reed switch, and the magnet may be damaged by impact.

On the other hand, as an alternative to the reed switch method, a Hall element method capable of detecting the approach of iron as a sensing element has been conventionally used. Conventionally, as a device for switching a stroke operation of a hydraulic cylinder in a high-viscosity fluid pump, a Hall element is employed, as shown in FIG.
As shown in (b), two high-viscosity fluid pressure-feeding cylinders 3 and 4 and two hydraulic cylinders 1 and 2 are integrally disposed via a cleaning chamber 5 as shown in FIG. Pistons 6 and 7 in the cylinders 3 and 4 and pistons 8 and 9 in the hydraulic cylinders 1 and 2 are integrally connected via rods 10 and 11, respectively. In a high-viscosity fluid pump in which high-viscosity fluid is sucked and discharged by the pressure-feeding cylinders 3 and 4 as the cylinder 9 moves forward and backward, pressure oil is supplied to the head-side pressure chambers of the two hydraulic cylinders 1 and 2. An electromagnetic switching valve 13 is provided in the middle of the line 12 for discharging, and the rod-side pressure chambers of the hydraulic cylinders 1 and 2 are connected to each other by a sealing circuit 14.
Proximity sensors LS1 and LS2 using Hall elements are provided at the forward stroke end on the rod side, and the sensing element of the piston 8 or 9 of the hydraulic cylinder 1 or 2 reaches the stroke end and is detected by the proximity sensor LS1 or LS2. When the detection is detected, when the output voltage of the proximity sensor LS1 or LS2 exceeds a certain fixed voltage (reference voltage), the controller 15 determines that the proximity sensor is ON and the electromagnetic switching valve 13
And outputs a switching signal to the solenoid SOL. 1 or SO
L. 2, the electromagnetic switching valve 13 is switched to alternately switch the hydraulic cylinders 1 and 2 between forward and backward operations.

The hydraulic cylinders 1, 2 and the proximity sensors LS1,
The relationship with LS2 is shown in FIG. 4B, where the hydraulic cylinder 1 and the proximity sensor LS1 are connected to each other.
An annular recess 18 is formed at the end position on the side of the cylinder 7 so as to communicate with the inside of the cylinder body 17 with the same diameter as the inside diameter of the cylinder body 17 so as to extend the rod-side pressure chamber partitioned by the piston 8. At the same time, a hole 19 communicating with the concave portion 18 is formed in the rod-side end block 16 so as to form the hole 1.
9, a proximity sensor LS1 using a Hall element is installed,
Further, a sensor 20 is attached to the rod-side pressure receiving surface of the piston 8, and when the piston 8 reaches the stroke end on the forward side, the sensor 20 enters the concave portion 18 and is detected by the proximity sensor LS1. 8, the forward stroke end position is detected. 2
Reference numeral 1 denotes a lead wire of the proximity sensor LS1.

However, despite the fact that the voltage difference between when the proximity sensors LS1 and LS2 sense the sensing element 20 of the pistons 8 and 9 and when they do not sense the sensor are substantially constant regardless of the temperature (oil temperature), Since the output voltage decreases as the temperature rises, and the output voltage increases as the oil temperature decreases, the following problem is caused.

When the oil temperature rises, the output voltages of the proximity sensors LS1 and LS2 decrease as shown in FIG.
When the sensing elements 20 of the hydraulic cylinders 1 and 2 are the proximity sensors LS1 and LS1,
Upon reaching the position of LS2, may output voltage becomes always OFF without exceeding the reference voltage V _R, therefore, the controller 15 does not output the switching command, switching of hydraulic cylinders 1, 2 May cause disability.

On the other hand, when the oil temperature decreases, the output voltages of the proximity sensors LS1 and LS2 increase as shown in FIG.
Even if the output voltage does not reach the positions of S1 and LS2, the output voltage may exceed the reference voltage V _R and become always ON, and the switching command from the controller 15 may be applied to the two hydraulic cylinders 1 and 2. Outputting at the same time may make it impossible to switch the hydraulic cylinders 1 and 2.

Further, when the hydraulic cylinders 1 and 2 cannot be switched, a reset operation of the controller 15 is required at the operation section of the high-viscosity fluid pump. Then, the operation of the operator returning from the workplace at the end of the boom to the operation unit and resetting it,
Waste of time.

Therefore, even if the output temperature of the proximity sensor changes due to a change in the oil temperature, the controller can accurately determine the ON / OFF operation of the proximity sensor so that the hydraulic cylinder cannot be switched. In order to prevent this from happening, the ON voltage of the proximity sensor and the OF
A configuration incorporating a reference voltage setting unit for holding a reference voltage at an intermediate level from the F-hour voltage has been recently proposed.

[0013] Such recently proposed that, as shown in FIG. 7, the same structure as that shown in FIG. 4, ON compares the operating voltage V with respect to the reference voltage V _R of the proximity sensor LS1 (or LS2) The ON-OFF determining unit 22 that outputs a rewrite command via the timer T when the sensor 20 is turned off, and when the sensor 20 of the piston 8 (or 9) comes to the position of the proximity sensor LS1 (or LS2) in advance. ON voltage V _ON and the sensor 20 of the piston 8 (or 9) move away from the proximity sensor LS1 (or LS2) and move to the rod 10 (or 1).
The ON-OFF intermediate voltage setting unit 25 that measures the OFF voltage V _OFF when only 1) is set and sets の of the difference between the OFF voltage V _OFF and the proximity sensor LS1 ( Or LS2) to the voltage V at that time measured by the intermediate voltage setting unit 25 (V _ON −V
A reference voltage setting unit 23 to a value obtained by adding the _OFF) / 2 was set as the next reference voltage V _R, the ON-O
The control unit 15 includes a switching command unit 24 that sends a switching command to the electromagnetic switching valve 13 in response to a command from the FF determination unit 22.

[0014]

According to the recently proposed technique, even if the oil temperature changes, the function of the reference voltage setting section keeps the reference voltage always between the ON voltage and the OFF voltage. Therefore, the ON / OFF operation of the proximity sensor can be accurately determined, and the switching of the hydraulic cylinder is not disabled.
Since the correction is made based on the output voltage at that time after a certain period of time, for example, when the moving direction is switched due to the effect of a low piston speed or a load, etc. Should the hunting of the piston occur, the following problems may occur. In other words, when the hunting occurs in the piston, if the hunting disappears before the fixed time t set by the timer T elapses as shown in FIGS. Can be performed, but when hunting does not disappear even after a certain time t has elapsed, FIG.
(C) As shown in (d), the output voltage of the proximity sensor does not drop to the normal OFF voltage, and sometimes becomes higher than the reference voltage in some cases. In this case, FIG.
As shown in (d), if the new reference voltage is rewritten to a considerably high value, the next switching may not be possible.

Therefore, the present invention is a further development of the above-mentioned recently proposed method, and even if a situation occurs in which the piston moves unstable near the stroke end,
This is to prevent an incorrect reference voltage value from being set.

[0016]

The present invention solves the above problems.
Pistons 8 and 9 alternately move back and forth to decide
Double row hydraulic cylinder consisting of a pair of two cylinders
At the stroke end positions on the same side of
Proximity sensors LS1 and LS2 using
The operating voltage V of each of the proximity sensors LS1, LS2₁, V_TwoWhen
Reference voltage V_R1, V _R2ON and OFF signal by comparison with
Based on the switching command from the controller 15 based on the above two hydraulic pressures
Cut the stroke of cylinders 1 and 2 in opposite directions
The stroke operation of the hydraulic cylinder which is changed
The switching control device or the switching of one hydraulic cylinder 26
Holes at both stroke end positions
Proximity sensors LS1 and LS2 using devices are installed
And the operating voltage V of each of the proximity sensors LS1 and LS2.₁, V
_TwoAnd reference voltage V_R1, V_R2ON / OFF signal by comparison with
The hydraulic system is switched by a switching command from the controller 15 based on the
The stroke operation of the cylinder 26 is switched.
Hydraulic cylinder stroke operation switching control device
And the operating voltage V of each of the proximity sensors LS1 and LS2.₁,
V_TwoIs measured, and the voltage V of one proximity sensor LS1 is measured.₁But
When switching from ON to OFF, the other proximity sensor LS2
ON voltage V set in advance_ON2And OFF
Hour voltage V_{OF F2}Of the voltage difference of
The voltage V of the LS2_TwoIn addition to the new reference voltage
Reference voltage V_R2Reference voltage setting unit 23
_TwoAnd the voltage V of the other proximity sensor LS2_TwoIs ON to O
Similarly, when it becomes FF, the new reference voltage of the proximity sensor LS1 is changed.
Pressure V_R1Reference voltage setting unit 23 that sets₁To
It is configured to be incorporated in the controller 15.

The sensor 20 of the piston 8 is a proximity sensor LS
When the stroke operation of the hydraulic cylinder is switched in the opposite direction after reaching one stroke end where the sensor 1 is installed, the proximity sensor LS1 changes from ON to OFF, and the ON and OFF measured in advance by the other proximity sensor LS2. Of the voltage difference at the time is the other proximity sensor LS
2 is added to the voltage at the time of the output, a new reference voltage is set, and this value is used as the next reference voltage V _R2 of the proximity sensor LS2. At this time, since the piston 9 is located at the opposite stroke end, the proximity sensor LS2 is always OFF. Therefore, even if the piston 8 makes an unstable movement in the vicinity of the proximity sensor LS1, it is not possible to rewrite an incorrect reference voltage value. on the other hand,
The same applies when the piston 9 reaches the proximity sensor LS2.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. As shown in FIGS. 4A and 4B, pressure is alternately applied to two hydraulic cylinders 1 and 2 as a double row hydraulic cylinder. The high pressure fluid is alternately sucked and discharged by the two pressure feeding cylinders 3 and 4 by supplying the oil and performing the forward / backward operation, and provided at the stroke ends of the two hydraulic cylinders 1 and 2. Controller 15 based on ON / OFF signal based on comparison with reference voltage of proximity sensors LS1 and LS2
In the high-viscosity fluid pump, the stroke operation switching control device of the high-viscosity fluid pump is configured to switch the electromagnetic switching valve 13 in response to a switching command from the controller to switch the forward / backward operation of the two hydraulic cylinders 1 and 2. At 15, one proximity sensor LS1 (or LS2) is ON
And a function of rewriting the reference voltage value of the other proximity sensor LS2 (or LS1) when the signal is turned off.

More specifically, the reference voltage of the proximity sensor LS1
V_R1Operating voltage V₁From ON to OFF by comparing
When the reference voltage is rewritten to the proximity sensor LS2 side.
ON-OFF determination unit 22 that outputs the command a2₁alike
Reference voltage V of proximity sensor LS2_R2Operating voltage V_Two
When the proximity sensor L changes from ON to OFF
ON-O that outputs reference voltage rewriting command a1 to S1 side
FF determination unit 22_TwoThe sensor 20 of the piston 8
ON voltage V when it comes to the position of contact sensor LS1 _ON1And Pi
The sensor 20 of the stone 8 moves away from the proximity sensor LS1 and
OFF voltage V when only head 10_OFF1Measure
ON-OFF intermediate voltage that sets 1/2 of the voltage difference
Setting unit 25₁Similarly, the sensor 20 of the piston 9 is
ON voltage V when it comes to the position of proximity sensor LS2_ON2When
When the sensor 20 of the piston 9 moves away from the proximity sensor LS2
OFF voltage V when only rod 11 is used_OFF2Measure
ON-OFF intermediate power to set 1/2 of the voltage difference
Pressure setting unit 25_TwoAnd the rewrite command a1 is output
Sometimes ON-OFF intermediate voltage setting unit 25₁Set value from
(V_ON1-V_OFF1) / 2 the proximity sensor LS1 at that time
Operating voltage V₁To add the next reference voltage to the new reference voltage.
Pressure V_R1Reference voltage set to be rewritten to
Setting unit 23₁Similarly, the rewrite command a2 is output.
ON-OFF intermediate voltage setting unit 25_TwoFrom
Constant value (V_ON2-V_OFF2) / 2 the proximity sensor L at that time
Operating voltage V of S2_TwoAnd add the next reference voltage to the new
Reference voltage V_R2Criteria set to be rewritten to
Voltage setting unit 23_TwoAnd the ON-OFF determination unit 22₁,
22_TwoSolenoid valve 13 based on the ON signal from
Id SOL. 2, SOL. Output switching command to 1
Switching command unit 24₁, 24_TwoAnd the controller 15
It is configured to be incorporated in.

Now, when the piston 8 of the hydraulic cylinder 1 reaches the forward stroke end, for example, as shown in FIG. 4A, the operating voltage of the proximity sensor LS1 becomes ON-OF.
It is compared with a reference voltage V _R1 at the F determining section 22 _1, the reference voltage V
When exceeding the _R1, since the ON signal is sent to the switching instructor 24 _1, solenoid SOL from switching instructor 24 _1. When the switching command is given to 2, the electromagnetic switching valve 13 is switched, and as a result, the piston 8 starts to move toward the backward stroke end. Then, the piston 8, by movement of the opposite, since the distance from the proximity sensor LS1, in ON-OFF determination unit 22 _1, the operating voltages V ₁ relative to the reference voltage V _R1 is turned OFF when the lower recognition And
Proximity sensor LS2 side of the reference voltage setting unit 23 _second reference voltage rewriting command a2 to is issued. At this time, the proximity sensor L
The corresponding piston 9 on the S2 side is located near the retraction stroke end, and the rod 11 is located near the proximity sensor LS2.
Only that will be located. Reference voltage setting unit 2
In 3 _2, the output voltage V ₂ of the proximity sensor LS2 (=
Sets a new reference voltage V _R2 by adding V _OFF2 setting value sent from the ON-OFF intermediate voltage setting unit 25 ₂₎ to _{(V 0N2 -V OFF2) / 2} , the reference voltage V _R2,
The ON-OFF determination unit 22 ₂ for proximity sensors LS2, to send as the next reference voltage.

Therefore, similarly, when the piston 9 reaches the forward stroke end, the ON-OFF determination section 22
At _2, ON based on the reference voltage V _R2, the detection of OFF is performed, the electromagnetic switching valve 13 is switched, the new reference voltage V _R1 at the reference voltage setting unit 23 ₁ is set on the basis of this, This reference voltage is ON-OFF for the proximity sensor LS1.
It sent as the next reference voltage determination unit 22 _1.

According to the present invention, the ON-OFF judging section 22 ₁ ,
22 near the opposite side by the OFF signal at the _second sensor LS
2, since the rewriting command is issued to the reference voltage setting units 23 ₂ and 23 ₁ of the LS ₁ at timings as shown in an example in FIG. 2, it is assumed that the pistons 8 and 9 show unstable operation near the stroke end. However, since the corresponding piston of the proximity sensor for rewriting is near the retreat-side stroke end, this unstable operation can be ignored. Therefore, it is possible to prevent a situation in which the values of the reference voltages V _R1 and V _R2 are erroneously rewritten, and
Also, it is possible to quickly respond to a sudden temperature change.

FIG. 3 shows another embodiment of the present invention, in which one hydraulic cylinder 26 as a return hydraulic cylinder is provided.
An example of application to a stroke operation switching control device will be described. That is, the proximity sensors LS1 and LS2 are provided at both stroke end positions on the forward side (rod side) and the backward side (head side) of one hydraulic cylinder 26, and the reference voltage V _R1 of each of the proximity sensors LS1 and LS2 is provided. , similar to oN by comparison with V _R2, the stroke operation switching control device for a hydraulic cylinder that is so as to switch the stroke movement of the hydraulic cylinder 26 by switching command from the controller 15 based on the OFF signal, shown in FIG. 1 Various control functions are provided to the controller 15. The same parts as those in FIG. 4A are denoted by the same reference numerals.

In the embodiment shown in FIG. 3, the value of the reference voltage is changed from ON to OFF by one of the proximity sensors LS1 (or LS2).
, The value of 1/2 of the voltage difference between the ON voltage and the OFF voltage of the other proximity sensor LS2 (or LS1) is added to the voltage at the time of OFF, and the other proximity sensor LS2 (or LS1) is added.
Since the reference voltage value of 1) can be used, there is no possibility that an incorrect reference voltage value is set as in the case of the above embodiment.

In the above embodiment, a case has been described in which a switching command from the controller 15 is given to the electromagnetic switching valve 13 in order to switch the stroke operation of the hydraulic cylinders 1, 2, and 26. When a double tilt oil pump is used as an oil pump for supplying hydraulic oil, various commands may be given to the double tilt oil pump without departing from the scope of the present invention. Of course, changes can be made.

[0027]

As described above, according to the stroke operation switching control apparatus for a hydraulic cylinder of the present invention, a double-row hydraulic cylinder composed of a pair of two cylinders in which the piston is moved back and forth alternately back and forth is the same. A proximity sensor using a Hall element is installed at the stroke end position on the side, and ON and OFF are performed by comparing the operating voltage of each proximity sensor with a reference voltage.
According to the switching command from the controller based on the OFF signal, the above 2
A stroke operation switching control device for a hydraulic cylinder that switches the stroke operations of two hydraulic cylinders in opposite directions, or a Hall element is used at both stroke end positions on the rod side and the head side of one hydraulic cylinder. The stroke operation of the hydraulic cylinder is switched by a switching command from a controller based on an ON / OFF signal based on comparison with a reference voltage of each proximity sensor. In the control device, when the operating voltage of each of the proximity sensors changes from ON to OFF, the value of 1/2 of the voltage difference between ON and OFF preset by the other proximity sensor is set to the value at that time. Each reference voltage setting to be the next new reference voltage of the other proximity sensor in addition to the voltage of the other proximity sensor Since the unit is incorporated in the controller, even if the piston makes an unstable movement such as hunting near the stroke end, there is no possibility that the piston will be rewritten to an erroneous reference voltage value. Excellent effects such as being able to respond quickly to temperature changes and improving the temperature characteristics of the electric responsive proximity sensor with high responsiveness so that it can be used with high reliability under a wide range of conditions. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a stroke operation switching control device for a hydraulic cylinder according to the present invention.

FIG. 2 is a conceptual diagram showing a reference voltage rewriting timing in the case of using the device of the present invention.

FIG. 3 is a schematic view showing another embodiment of the present invention.

FIG. 4 shows an example of a stroke operation switching control device of a hydraulic cylinder in a conventional high-viscosity fluid pump.
(A) is an overall schematic diagram, and (B) is a schematic diagram showing a coupling structure between a hydraulic cylinder and a proximity sensor.

FIG. 5 is an output diagram of a conventional proximity sensor showing a state when the oil temperature rises in the related art.

FIG. 6 is an output diagram of a conventional proximity sensor showing a state at the time of a decrease in oil temperature in the related art.

FIG. 7 is a block diagram showing an example of a recently proposed hydraulic cylinder stroke operation switching control device.

8 shows the relationship between the reference voltage and the operating voltage in the case of the device shown in FIG. 7, wherein (a) and (b) show an example in which the reference voltage is normally rewritten, and (c) shows the reference voltage. FIG. 4D is a diagram illustrating an example in which the switch is slightly higher but does not hinder the switching, and FIG. 4D is a diagram illustrating an example in which the next switch becomes impossible.

[Description of Signs] 1, 2 Hydraulic Cylinders 8, 9 Piston 15 Controllers 22 ₁ , 22 ₂ ON-OFF Judgment Units 23 ₁ , 23 ₂ Reference Voltage Setting Units 24 ₁ , 24 ₂ Switching Command Units 25 ₁ , 25 ₂ ON -OFF intermediate voltage setting unit 26 Hydraulic cylinder LS1, LS2 Proximity sensor

Claims (2)

[Claims] 1. A proximity sensor using a Hall element is installed at a stroke end position on the same side of a pair of double-row hydraulic cylinders each of which is configured to alternately move a piston back and forth and backward. A stroke operation switching of the hydraulic cylinders in which the stroke operations of the two hydraulic cylinders are switched in opposite directions by a switching command from a controller based on an ON / OFF signal based on a comparison between an operation voltage of the proximity sensor and a reference voltage. In the control device,
When the operating voltage of each of the proximity sensors changes from ON to OFF, the ON of the other proximity sensor is set in advance.
Each reference voltage setting unit, which adds a value of 電 圧 of the voltage difference between the time when the sensor is turned off and the voltage when the current sensor is turned off to the voltage of the other proximity sensor at that time and sets it as the next new reference voltage of the other proximity sensor, A stroke operation switching control device for a hydraulic cylinder, characterized in that it has a configuration incorporated in a vessel. 2. Proximity sensors using Hall elements are installed at both stroke end positions on a rod side and a head side of one hydraulic cylinder, and ON is performed by comparing an operation voltage of each proximity sensor with a reference voltage. In the stroke operation switching control device for a hydraulic cylinder, which switches the stroke operation of the hydraulic cylinder in accordance with a switching command from a controller based on an OFF signal, when the operation voltage of each of the proximity sensors changes from ON to OFF, The value of 1/2 of the voltage difference between ON and OFF preset by the other proximity sensor is added to the voltage of the other proximity sensor at that time, and the next new reference voltage of the other proximity sensor is added. A stroke operation switching control device for a hydraulic cylinder, wherein each reference voltage setting unit is configured to be incorporated in the controller.