JP2576216B2 - Flow control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flow control device.

[Conventional technology]

Generally, in a cargo handling control device for an industrial vehicle, for example, a forklift, as shown in FIG.
Is detected by the lever operation amount detection sensor 42, and the detection value of the sensor 42 is taken into the controller 43. The controller 43 outputs a pulse signal having a duty ratio corresponding to the operation amount of the lift lever 41 to two electromagnetic pilot valves.
The output to 44a, 44b controls the opening of the control valve 45.

That is, the lift lever 41 is provided so as to be tiltable upward and downward with respect to the neutral position, and the controller 43 corresponds to the lever operation amount on the upward or downward side with respect to the dead zone corresponding to the neutral position adjacent range. Output to one of the pilot valves 44a, 44b. As a result, the opening of the control valve 45 is adjusted at the position a or the position b, and the lift cylinder 46 is expanded and contracted to adjust the amount of elevation of the fork.

[Problems to be solved by the invention]

However, the spool of the control valve 45 described above
47 slides on the inner wall of the valve chamber 48, and when it moves, friction occurs between the two 47, 48. When the lift lever 41 is moved upward from the neutral position to raise the fork and the valve opening is increased at the position of the spool 47, the fork load gradually increases from the lift cylinder 46 to the port of the spool 47 due to the load of the fork. Hydraulic pressure is applied. Similarly, when the lift lever 41 is returned to the neutral position slightly on the ascending side to reduce the fork's ascending speed, the spool 47 is moved from the lift cylinder 46 to the spool 47 to reduce the valve opening at the position b.
The hydraulic pressure acting on the port becomes smaller.

Conversely, when the lift lever 41 is operated to the lower side, the spool 47 increases the valve opening at the position a, and the hydraulic oil in the lift cylinder 46 quickly escapes to the drain side due to the load from the fork, and the spool 47 The hydraulic pressure acting on port 47 will be small. When the lift lever 41 is returned to the neutral side slightly on the descending side and the fork descending speed is reduced, the hydraulic pressure acting on the port of the spool 47 from the lift cylinder 46 is reduced because the spool 47 decreases the valve opening at the position a. growing.

Accordingly, the force acting on the spool 47 of the control valve 45 orthogonally varies depending on the operation direction of the lift lever 41, and a difference is generated between the spool 47 and the inner wall of the valve chamber 48. Thus, when the operation direction of the lift lever 41 is different, the resistance received by the spool 47 when moving is different, which adversely affects the valve opening.
Therefore, according to the operation amount of the lift lever 41, the controller
It is difficult to accurately adjust the amount of hydraulic oil in the lift cylinder 46 only by the current that the 43 outputs to the pilot valves 44a and 44b, and it is not possible to perform highly accurate fork elevating control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to adjust the amount of hydraulic oil in a cargo handling control device in accordance with the operation amount of the operation means even when the operation direction of the operation means is different. An object of the present invention is to provide a flow control device capable of performing accurate control and performing flow control with high accuracy.

[Means for solving the problem]

In order to achieve the above object, the present invention is capable of reciprocating to a first region with respect to a neutral position,
Operating means capable of reciprocating to the other second area with respect to the neutral position; and first means when the operating means is located in the first area.
And when the operating means is located in the second region, the operation channel is switched to a second operation channel switching state different from the first operation channel switching state,
When the operating means is located at the neutral position, it is switched to the non-operating flow path switching state, and in the both operating flow path switching states, a valve for adjusting the flow rate of the fluid by the valve opening degree, and an operating amount of the operating means. An operation amount detection means for detecting, an operation area determination means for determining whether the operation means is located in the first area, the second area, or the neutral position; Reciprocating motion determining means for determining whether the operation is a moving operation or a returning operation; and whether the operating means is in the first area or the second area and whether the operating means is the forward operation or the backward operation. Regardless, so that the flow rate of the fluid is uniquely determined with respect to the operation amount of the operation means,
The valve opening degree data for the operation amount when the operating means is located in the first area and the forward operation is performed, and the valve opening degree data for the operation amount when the operating means is located in the first area and the backward operation is performed. The valve opening data, the valve opening data for the operation amount when the operating means is located in the second area and the forward operation is performed, and the operating means is located in the second area and operated backward. Storage means for respectively storing valve opening degree data corresponding to an operation amount when the operation is performed, and the first operation flow path switching state and the second operation flow path based on an operation area detection means when the operation means is operated. The valve is controlled to be switched between a switching state and the non-operating flow path switching state, and when in the first operating flow path switching state or the second operating flow path switching state, the operation amount detecting means and the operation area The determination means, and the reciprocating motion determination means based on the Valve control for reading predetermined valve opening data from the storage means and adjusting the valve opening of the valve so that the flow rate of the fluid is uniquely determined based on the operation amount of the operating means based on the valve opening data The gist is that the means are provided.

[Action]

By the above means, the operation amount of the operating means is detected by the operation amount detecting means, the reciprocating operation determining means determines whether the operation of the operating means is the forward operation or the backward operation, and the operating area determining means determines the operating amount of the operating means. Is located in the first area, the second area, or the neutral position.

The valve control means controls to switch the valve to the first working flow path switching state when the operation area is determined to be located in the first area by the operation area detection means, and the operation means is located in the second area. If it is determined that the first
The valve is controlled to be switched to a second operation flow path switching state different from the operation flow path switching state, and the valve is controlled to be switched to a non-operation flow path switching state when it is determined that the operating means is located at the neutral position. .

Further, when switching the valve to the first working flow path switching state or the second working flow path switching state, the valve control means
Based on the detection and discrimination results from the operation amount detecting means, the operation area discriminating means, and the reciprocating motion discriminating means, predetermined valve opening data stored in the storage means is read.

In this storage means, whether the operation means is in the first area or the second
Irrespective of whether it is in the area or not and whether the operating means is a forward operation or a backward operation, the operating means is configured such that the flow rate of the fluid is uniquely determined with respect to the operation amount of the operating means. The valve opening degree data of the valve is divided by the forward operation in the first region, the backward operation in the first region, the forward operation in the second region, and the backward operation in the second region. It is remembered.

Then, the valve control means adjusts the valve opening degree of the valve based on the valve opening degree data read from the storage means.

Therefore, regardless of whether the operating means is in the first area or the second area, and regardless of whether the operating means is a forward operation or a backward operation, the operation amount of the operating means is univocally determined. Since the flow rate of the fluid is determined, highly accurate flow rate control according to the operation of the operation means is performed.

〔Example〕

Hereinafter, a first embodiment in which the present invention is embodied in a cargo handling circuit of a forklift will be described with reference to FIGS. 1 to 4.

FIG. 2 shows a hydraulic circuit of the lift cylinder 11, in which the fork 12 shown in FIG. 1 is moved up and down by the expansion and contraction of a rod 11a of the cylinder 11.
The oil pump 13 discharges the hydraulic oil in the tank T to the flow dividing valve 14 through the discharge line 15, and the discharged oil is divided into a main line 15a connected to the control valve 9 as a valve and a power steering line 15b. . The valve chamber 18 of the control valve 9 communicates with the pilot operation oil chamber 19 adjacent thereto through an insertion hole 20, and one end of a pilot piston 28 disposed in the pilot operation oil chamber 19 projects from the insertion hole 20. And is connected to a spool 21 in the valve chamber 18. The elastic force of the pressing spring 22 for urging the spool 21 in the valve chamber 18 and the elastic force of the pressing spring 23 for urging the piston 28 in the pilot operation oil chamber 19 are balanced.
Is always held at the neutral position as the non-operating flow path switching state.

A pilot introduction pipe 24 is branched from the power steering pipe 15b, and a pressure reducing valve 25 is connected to the pilot introduction pipe 24. Further, the downstream side of the pressure reducing valve 25 of the pilot introduction pipe 24 is further branched, and two inflow ports 29 formed in the pilot operation oil chamber 19 through the electromagnetic pilot valves 26 and 27 for lowering and raising, respectively. , 30
It is connected to the. Outlet ports 31, 32 are provided in the pilot operation oil chamber 19 corresponding to the inflow ports 29, 30,
The outflow ports 31, 32 are connected to a return line 33 via orifices 34, 35.

Each of the electromagnetic pilot valves 26 and 27 is always closed and selectively opened by the duty control of the controller 3 described later. As a result, the pilot pressure oil reduced in pressure by the pressure reducing valve 25 flows from the introduction line 24 to the pilot operation oil chamber 19.
On the other hand, the flow rate of the pilot pressure oil flowing out of the outflow ports 31, 32 of the pilot operation oil chamber 19 is restricted by the orifices 34, 35, and the pilot pressure acting on the piston head 28a and the push springs 22, The spool 21 is displaced until the elastic force of the spool 23 is balanced.

Therefore, by selecting and driving the electromagnetic pilot valves 26 and 27, the spool 21 is moved to the a position as the first operating flow path switching state or the b position as the second operating flow path switching state.
Switched to position. Then, the ascending electromagnetic pilot valve 27 is excited, and when the spool 21 is switched to the position b, the rod 11a extends and the fork 12 ascends, and conversely, the descending electromagnetic pilot valve 26 is excited, spool
When 21 is switched to the a position, the rod 11a contracts,
The fork 12 will descend.

Further, by controlling the duty ratio of the exciting current input to both electromagnetic pilot valves 26 and 27 and adjusting the open time of one of the electromagnetic pilot valves 26 and 27, a , b, the opening at each position is adjusted, and the outflow and inflow of hydraulic oil to and from the lift cylinder 11 are controlled. That is, by selectively controlling the duty ratio of the exciting current of the electromagnetic pilot valves 26 and 27, each speed of the fork 12 at the time of ascent and descent can be controlled.

Next, an electrical configuration for driving and controlling the electromagnetic pilot valves 26 and 27 provided in the control valve 9 will be described with reference to FIG.

The lift lever 1 serving as operating means provided on the driver's seat of the forklift lifts up (the ascending operation area which is the first area in the present embodiment) and descends (the second area in the present embodiment) based on the neutral position. When the lift lever 1 is in the ascending operation area, the fork 12 moves up, and when the lift lever 1 is in the descending operation area, the fork 12 moves down. Also fork
The ascending speed and the descending speed of 12 are adjusted by the operation amount of the lift lever 1 in each of the ascending and descending operation regions. The lever operation amount is detected by a lever operation amount detection sensor 2 as an operation amount detection means constituted by a potentiometer, and a signal based on the detection result is input to the controller 3.

The controller 3 is an A / D converter 4 and a central processing unit (C
PU) 5, read-only memory (ROM) 6a, readable and rewritable memory (RA
M) 6b, a PWM generation circuit (pulse width modulation circuit) 7, and the like. An analog detection signal of the lever operation amount detection sensor 2 is converted into a digital signal by an A / D converter 4 and inputted to a CPU 5 as an operation area discriminating means, a reciprocating motion discriminating means and a valve control means.

The CPU 5 performs a processing operation according to a control program stored in a ROM 6a as storage means,
Based on the detection data of the lever operation amount detection sensor 2, the operation amount of the lift lever 1 at that time is calculated,
The lift lever 1 in each of the ascending and descending operation areas
Is an operation in the direction away from the neutral position to increase the ascent and descent speeds (forward operation) or an operation in the direction to return to the neutral position side to decrease the ascent and descent speeds (backward operation) Is to be determined. Then, the CPU 5 determines which of the ascending and descending electromagnetic pilot valves 26, 27 is to be excited based on the result of the indexing, and based on the valve opening degree data stored in the ROM 6a in advance, the CPU 5 determines whether the electromagnetic pilot valve 26, 27 is to be excited. The speed or the descent speed is determined. That is, in the case of ascending, the CPU 5 controls the excitation of the ascending electromagnetic pilot valve 27, and in the case of descending, the CPU 5 controls the excitation of the descending electromagnetic pilot valve 26.

As shown in FIG. 3, the flow rate data stored in the ROM 6a is (duty ratio) data of the exciting current value of the electromagnetic pilot valves 26 and 27 with respect to the operation amount of the lift lever 1 in the ascending and descending operation regions (that is, the duty ratio). , Valve opening degree data for determining the ascending speed and the descending speed). In this embodiment, the ascending speed and the descending speed are respectively determined by the forward and backward operation amounts in the ascending and descending operation regions. Are different.

That is, as shown in FIG. 3, in the case of the forward operation in the ascending operation area, the exciting current value (duty ratio) of the ascending electromagnetic pilot valve 27 with respect to the operation amount is determined based on the control lines UL5 to UL9. Conversely, in the case of the return operation, the exciting current value (duty ratio) of the electromagnetic pilot valve 27 with respect to the operation amount is determined based on the control lines UL1 to UL5.
Therefore, even if the operation amount of the lift lever 1 is the same, the control differs depending on whether it is based on the forward operation or the backward operation. Moreover, in the present embodiment, different control lines UL1 to UL9 are provided for each predetermined operation range of the forward operation and the backward operation.
Is set.

On the other hand, in the descending operation region, similarly, in the case of the forward operation, the descending operation is performed in accordance with the operation amount based on the control lines DL5 to DL9, and in the case of the backward operation, based on DL1 to DL5. The duty ratio of the exciting current to drive the electromagnetic pilot valve 26 is determined.

When the CPU 5 determines the exciting current value (duty ratio), the PW
By controlling the excitation of the electromagnetic pilot valves 26 and 27 via the M generating circuit 7, the opening time thereof is adjusted.

Next, the operation of the present flow control device will be described with reference to the flowchart of FIG. 4 showing the processing operation of the CPU 5.

Now, the lift lever 1 is operated from the neutral position to the ascending operation area side (forward movement operation), and the operation amount exceeds a predetermined operation amount (dead zone) in step S1 (hereinafter, step is simply referred to as S). When the CPU 5 determines that the CPU 5 stores the operation amount at that time in the RAM 6a in S2, the CPU 5 stores the operation amount in the RAM 6a, and then in S3, 20 msec
stand by. After that time has elapsed, the CPU 5 calculates the operation amount of the lift lever 1 at that time in S4 and S5, and operates the lift lever 1 in either the operation region of the ascending operation region or the operation region of the descending operation based on the obtained operation amount. To determine if it is.

That is, in this embodiment, the lever operation amount detection sensor 2 is constituted by a potentiometer, the output voltage value be adapted to output a detection voltage between 0 volts V _max, the neutral position of the lift lever 1 Output voltage Vc
It is set to be 1/2 of the V _max. Accordingly, when the lift lever 1 is moved forward in the ascending operation region, the detected voltage gradually increases, and when the lift lever 1 is moved forward in the descending operation region, the detected voltage gradually decreases.

As a result, when the detected voltage Vc with respect to the operation amount of the lift lever 1 at that time is a value larger than the value in consideration of the dead zone, the CPU 5 falls in the ascending operation region, and conversely, when the detected voltage Vc is smaller than the value in consideration of the dead zone, the voltage falls. It is determined that it is in the operation area.

Then, when it is determined in S5 that the current operation amount is in the ascending operation area, the magnitude of the detected operation amount with respect to the operation amount before 20 msec is compared with the obtained operation amount in S6. If the operation is smaller than the operation, the operation is determined to be a return operation.

If it is determined that the operation is a forward operation, valve opening data based on the forward operation is calculated in S7. That is, in this case, the duty ratio of the exciting current value to the operation amount in the forward operation in the ascending operation area is the valve opening data (control line U) stored in the ROM 6a.
L5 to UL9). Next, in S8, the ascending electromagnetic pilot valve 27 is excitation-controlled to increase the hydraulic oil in the lift cylinder 11 and raise the fork 12.
Thereafter, the CPU 5 obtains a new operation amount every 20 msec, and repeats the above-described operation based on the operation amount and the previous operation amount, whereby the ascending speed of the fork 12 gradually increases.

Now, when the lift lever 1 is operated to slightly lower the ascending speed, that is, when the lift lever 1 is returned to the neutral position side, it is determined in S6 that the operation is the return operation, and in S9, the operation in the return operation of the ascending operation area is performed. The duty ratio of the exciting current value to the amount is ROM6a
Is calculated based on the valve opening data (control lines UL1 to UL5) stored in step S8, and in step S8, the ascending electromagnetic pilot valve 27 is excitation-controlled. Therefore, the spool 21 at the position b is moved and adjusted by the pilot pressure, the valve opening of the control valve 9 is reduced, and the ascending speed of the fork 12 is reduced.

On the other hand, regarding the operation of the lift lever 1 in the descending operation area, the CPU 5 determines in S5 that the detection voltage Vc for the operation amount at that time becomes smaller than the value in consideration of the dead zone, and thus the CPU 5 is in the descending operation area. . Then, in S10, it is determined whether the operation is the forward operation or the backward operation by comparing the current operation amount with the operation amount 20 msec earlier. That is, in this case, it is determined that the forward operation is performed when the detected voltage for the current operation amount is smaller than the detected voltage with respect to the current operation amount, and the reverse operation is performed when the detected voltage is larger than the detected operation amount.

In the case of the forward operation, the duty ratio of the exciting current value to the operation amount in the forward operation of the descending operation area in S7 corresponds to the valve opening degree data (control lines DL5 to DL5) stored in the ROM 6a.
DL9), and in step S8, controls the excitation of the descending electromagnetic pilot valve 26 at the determined duty ratio. Then, the position of the spool 21 at the position a is adjusted to increase the valve opening of the control valve 9, and the fork 12
Is lowered.

In addition, when the lift lever 1 is moved backward, that is, returned to the neutral position side in order to slightly lower the descending speed, it is determined in S10 that the operation is a return operation. Then, in S9, the duty ratio of the exciting current value to the operation amount in the return operation of the descending operation area is calculated based on the valve opening data (control lines DL1 to DL5) stored in the ROM 6a, and is at the position a by the pilot pressure. The movement of the spool 21 is adjusted, the valve opening of the control valve 9 is reduced, and the lowering speed of the fork 12 is reduced.

As described above, in the present embodiment, although the operation amount of the lift lever 1 is the same, the opening degree of the control valve 9 differs depending on the operation method (forward operation and backward operation). In order to solve the problem, the controller 3 changes the duty ratio of the signal output to the electromagnetic pilot valves 26 and 27 according to the operation amount for each operation direction, and changes the valve opening of the control valve 9 to the operation amount of the lift lever 1. Is always followed, so that the oil amount in the lift cylinder 11 is properly maintained, and accurate control of lifting and lowering the fork 12 can be performed.

Also, when shifting from the dead zone to the ascending operation area and the descending operation area, the rise of the current value in the ascending start part and the descending start part is moderated.
The movement of the fork 12 is performed at a very low speed, and the slight lifting and lowering operation of the fork 12 can be performed easily and accurately, so that the lifting and lowering operability is excellent.

〔effect〕

As described above in detail, according to the present invention, the valve opening degree data is set according to the operation amount of the operation means, the operation area (first area / second area), and the operation direction (forward / backward). Therefore, an excellent effect of accurately controlling the opening degree of the valve in accordance with the operation amount of the operation means and enabling high-precision flow control is exhibited.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing an electrical configuration of an embodiment of the present invention, FIG. 2 is a circuit diagram showing a hydraulic configuration of the embodiment, and FIG. 3 shows a relationship between a lever operation amount and a duty ratio. FIG. 4 is a flowchart showing the operation of the CPU,
FIG. 5 is a hydraulic circuit diagram showing a conventional example. Lift lever 1 as operation means, lever operation amount detection sensor 2 as operation amount detection means, operation area determination means,
A CPU 5 as a reciprocating motion determining means and a valve control means, a ROM 6a as a storage means, and a control valve 9 as a valve.

Claims (1)

(57) [Claims] 1. An operating means operable to reciprocate to one first area with respect to a neutral position and operable to reciprocate to another second area with respect to a neutral position, and the operating means is located in the first area. In this case, the state is switched to the first operation flow path switching state, and
When it is located in the area, it is switched to a second operating channel switching state different from the first operating channel switching state, and when it is located in the neutral position, it is switched to a non-operating channel switching state. A valve that adjusts a flow rate of a fluid by a valve opening degree in the both operation flow path switching state, an operation amount detection unit that detects an operation amount of the operation unit, and whether the operation unit is located in the first region. Operating area determining means for determining whether the operating means is located in the second area or the neutral position; reciprocating operation determining means for determining whether the operating means is a forward operation or a backward operation; Irrespective of whether the means is in the first area or the second area, and whether the operation means is the forward operation or the backward operation, the flow rate of the fluid is uniquely determined by the operation amount of the operation means. Determines that the operating means is in the first area And the valve opening degree data with respect to the operation amount when the forward operation is performed, and the valve opening degree data with respect to the operation amount when the operation means is positioned in the first area and the backward operation is performed. Valve opening degree data for the operation amount when the operating means is located in the second area and the forward operation is performed, and the valve opening data for the operation amount when the operating means is located in the second area and the backward operation is performed Storage means for storing the opening degree data respectively; and when the operation means is operated, the first operation flow path switching state, the second operation flow path switching state, or the non-operation state based on the operation area detection means. The valve is controlled to be switched to one of the operating flow path switching states, and when in the first operating flow path switching state or the second operating flow path switching state, the operation amount detecting means, the operation area determining means, and the reciprocating operation determination Opening a predetermined valve from the storage means based on the means Valve data reading means, and valve control means for adjusting the valve opening degree of the valve such that the flow rate of the fluid is uniquely determined with respect to the operation amount of the operation means based on the valve opening degree data. Control device.