JPH04171304A - Proportional solenoid type directional flow rate control valve - Google Patents

Abstract

PURPOSE:To center main spool with certainty by arranging a solenoid changeover valve which introduces a pilot pressure to one oil chamber of a centering piston to be followed by a main spool through switching as required between a pilot member which is displaced proportionally to an output pressure of a pilot pressure control valve and the main spool. CONSTITUTION:An output of a pilot pressure control valve 100 having a proportional solenoid 50 is applied to one oil chamber of a pilot piston 105, while a pilot pressure is introduced into the other oil chamber 108 through a solenoid changeover valve 113. A centering piston 107 is arranged being in contact with the pilot piston 105, position of which piston 107 is changed according to the hydraulic pressure in the oil chamber 108. The centering piston 107 is followed by a main piston 204 through a flapper 206 and a nozzle 207. It is not necessary to arrange a pilot spool 101 and the main spool 204. The device is downsized and centering of the main spool 204 is carried out with certainty.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position-following type electromagnetic directional flow control valve using a spool-type pressure control valve using a single solenoid as a pilot.

[Prior Art] FIGS. 11 to 13 are structural diagrams of a conventional position-following type directional flow control valve using a single solenoid. In each figure, the main spool 40 is positioned to follow the flapper 18.

FIG. 11 shows the state when the proportional solenoid 13 is completely OFF and the hydraulic pilot P is also OFF, and the main spool 40 is held neutrally by the centering springs 12 on both sides.

Fig. 12 shows a state in which the hydraulic pilot P is ON (hydraulic pressure is supplied) and a current of approximately 1/2 of the rated value is also supplied to the proportional solenoid 13, and its output displaces the spring 19 to exactly The main spool 40 is designed to be in a neutral state at times.

Figure 13 shows a case where the hydraulic pilot P is ON and the proportional solenoid 13 reaches its maximum state on one side (from the P boat to the A
flow into the port), which is the state where the current is O.

FIG. 14 is a characteristic diagram of the proportional solenoid current and flow ff1Q including the cases shown in FIGS. 11 to 13 above.

[Problems to be Solved by the Invention] However, with such conventional electromagnetic directional flow control valves, certain procedures are required even when making an emergency stop, and in some cases, the main spool must be opened once. Then, the phenomenon of returning occurs. That is, when the power supply to both the hydraulic pilot and the proportional solenoid is turned off from the state shown in FIG. 12, the hydraulic pressure generation source generally lags behind the time when the power is turned off due to the inertia of the electric motor. Therefore, only the proportional solenoid is turned off while the pilot oil pressure remains.
F, the main spool follows the flapper and moves to the state shown in FIG. 13 until the oil pressure is turned off. For this reason,
There was a problem in that this property had to be fully taken into consideration when designing the device.

The present invention was made to solve these problems, and an object of the present invention is to provide a directional flow control valve that can reliably center the main spool in the above-mentioned predetermined cases.

[Means for Solving the Problems] The proportional electromagnetic directional flow control valve according to the present invention includes a pilot pressure control valve that outputs pressure by a single proportional solenoid and a pilot spool, and a pilot pressure control valve that controls the output pressure of the pressure control valve. a proportionally displaced pilot member; a centering piston between the pilot member and the main spool;
An electromagnetic switching valve introduces pilot pressure into at least one oil chamber of the centering piston, and the main spool is a hydraulic pilot-driven type that moves following the centering piston. It is configured so that it can be switched.

[Operation] In the present invention, a pressure proportional to the input current of the proportional solenoid is output from the pilot pressure control valve, thereby operating the main spool via the pilot member and the centering piston. Then, in a predetermined case, if the electromagnetic switching valve is switched to introduce pilot pressure into the oil chamber of the centering piston, the centering piston is displaced to the centering position, and the main spool is also centered.

[Example] FIG. 1 is a structural diagram showing an embodiment of the present invention.

The pilot pressure control valve 100 is of a pressure reducing valve type, and the pilot spool 101 outputs a pressure P corresponding to the output of the proportional solenoid 50 to the oil chamber 102, which acts on the pilot piston 105 via the oil passage 104. The left oil chamber 109 of the centering piston 107 is always in communication with the drain Dr3, and the right oil chamber 108 is in communication with the drain Dr5 through the switching solenoid valve 113 during normal control. FIG. 2 shows that when the current supplied to the proportional solenoid 50 is zero, and when the main spool 204 is in the neutral position and the input current is about 50%, the switching solenoid valve 113 switches and the pressure P increases to the orifice 1.
14, it is introduced into the right side chamber 10g, and the opening between the centering piston 107 and the groove ill is the same as the orifice 1.
This figure shows a state in which the vehicle is stopped at a position corresponding to 14.

FIG. 3 shows the centering piston 1 using the switching solenoid valve 113.
Pilot pressure is introduced into the left and right oil chambers 108, 109 of 07, and orifices 200, 201 are provided in the grooves 111, 202 and the oil passages connected to the oil chambers 10B, 109, respectively. According to this, centering piston 1
07 is reliably held at the center by hydraulic pressure no matter where the main spool 204 is located, and therefore the main spool 204 is also centered.

FIG. 4 shows an example in which the pilot pressure control valve is of a throttle valve type. 200 indicates a throttle valve type pilot pressure control valve.

Figure 5 is a modification of part A in Figure 4, and includes three switching solenoid valves.
1,502,503 installed, and left and right oil chambers 108°1
An orifice 504 is provided in the oil passage connecting 09, and any 1
The centering piston 107 is centered when these solenoid valves are switched.

FIG. 6 shows another embodiment of the present invention, in which a switching solenoid valve is provided in addition to the solenoid valve 301 for dealing with the current OFF of the proportional solenoid, and a cam valve is provided in relation to the left oil chamber 109 from the P boat to the B boat. When the cam valve 302 returns to the position shown in the figure (for example, when the operation door of the injection molding machine opens,
In order to stop the mold closing operation, the cam valve 302 is activated by the movement of the door.
(switching) to return the centering piston 107 to neutral. The throttle 303 is a dual switching valve 301, 302
The design is such that the centering piston 107 can move smoothly when both or one of the pistons is blocked.

FIG. 7 shows another embodiment of the present invention, which is a modification of FIG. 6. This describes the type and usage (excitation) of the solenoid valve 601 and cam valve 602 as switching valves.

(Demagnetization) is different, and orifices 603 and 804 are provided in place of the orifice 303 in FIG.

FIG. 8 shows still another embodiment, in which a solenoid valve 401 is provided for the right oil chamber 10g of the centering piston 107, and a solenoid valve 402 is provided for the left oil chamber 109. In this case, the shape of the solenoid valve 401 eliminates the need for a pilot piston. In this FIG. 8, a solenoid valve 401
This is the case when the centering piston 107 is in the centering position. When the solenoid valve 401 is energized, the pilot pressure reducing valve 100 and the right oil chamber 108 communicate with each other, and the groove il
The outflow from l to the drain Dr6 is prevented.

FIG. 9 shows a characteristic diagram of the input current I and the flow ff1Q of the proportional solenoid in FIGS. 1 and 2, and a state diagram of the electromagnetic switching valve. (a) is the case where the electromagnetic switching valve 113 acts only when the proportional solenoid 50 is OFF, and (b)
) is the case where the electromagnetic switching valve 113 acts when the proportional solenoid 5o is OFF and when the current is in the neutral state.

Figure 1O is an example of a block diagram of the electrical system in the case of Figure 9, and Figure 10(a) corresponds to Figure 9(a), and Figure 10(b) corresponds to Figure 9(b). This is what I did. In Figure 1O (a), the comparator acts to drive the electromagnetic switching valve when the input current to the proportional solenoid is 0 to 5%.
In Figure 1O (b), the input current to the proportional solenoid is 0~
1% and 45% to 55%, the electromagnetic switching valve is driven. In addition, Fig. 10 (a), (b
), it is also possible to arbitrarily return the main spool to neutral using an external signal. Moreover, FIG. 10(a) is an example in which an input signal is detected, and FIG. 10(b) is an example in which an actual current is detected. In the case of Fig. 10(b), the electromagnetic switching valve turns on every time the proportional solenoid returns to the neutral state, so
This prevents stickiness due to the same operation for a long time and improves integrity.

Note that the type of electromagnetic switching valve and the direction of magnetization and demagnetization may be selected depending on the purpose of use.

Furthermore, in the above embodiments, the nozzle and flapper type was used as the method of following the position of the main spool relative to the pilot member, but a spool, sleeve type, etc. may also be used.

Furthermore, in the above embodiment, the electromagnetic switching valve is switched when the input current to the proportional solenoid is approximately zero and when the input current is approximately 50% at which the main spool is in the neutral position, but the command current to the proportional solenoid is It is also possible to switch when the current is approximately zero or when the command current is outside the control range of the proportional solenoid.

[Effects of the Invention] As explained above, according to the present invention, it is not necessary to arrange the pilot spool and the main spool on the same straight line in a position-following type directional flow control valve using a single proportional solenoid. , can be made compact. In addition, if the electromagnetic switching valve is set to a specified value (for example, proportional solenoid
By displacing the centering piston to the centering position, the main spool can be reliably centered not only when hydraulic pressure is not applied (such as during FF) but also even when hydraulic pressure is applied. Furthermore, regardless of the status of the main spool, it can be returned to neutral at will.

In addition, the solenoid switching valve is faster in the OFF operation of the proportional solenoid and the response of the electromagnetic switching valve, so it can be turned OFF at the same time.
Even if F is applied, the main spool remains neutral or moves toward neutral.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of an embodiment according to the present invention, and FIG. 2 is a structural diagram of an embodiment of the present invention.
Structural diagram of the electromagnetic switching valve in the state shown in the figure, Figures 3 to 8
The figures are structural diagrams of different embodiments according to the present invention, FIG. 9 is a characteristic diagram of the proportional solenoid input current and flow rate Q in FIGS. 1 and 2, and a switching state diagram of the electromagnetic switching valve.
The figure is a system block diagram of the electrical system corresponding to Figure 9, Figures 11 to 13 are structural diagrams of the conventional example, and Figure 14 is the system block diagram of the electrical system corresponding to Figure 11.
- It is a characteristic diagram of the proportional solenoid input current (■) of FIG. 13 and the current ff1Q. In each figure, the same reference numerals indicate the same or corresponding parts. 50...Proportional solenoid, 100,200...Pilot pressure control valve, 101.208...Pilot spool, 05...Pilot piston, 107...
・Centering piston, 108... Right oil chamber of the centering piston, 109... Left oil chamber of the centering piston, 113° 301.401, 402, 501
,502,503.601...Solenoid switching valve, 204.
...Main spool, 205...Spring, 206...
・Flapper, 207...Nozzle agent Patent attorney Souji Sasaki Figure 5 (b) Figure 9 (Q) (b) Figure 10 Figure 14

Claims (1)

[Claims] A pilot pressure control valve that outputs and controls pressure using a single proportional solenoid and a pilot spool, a pilot member that is displaced in proportion to the output pressure of the pressure control valve, and a joint between the pilot member and the main spool. A centering piston and an electromagnetic switching valve that introduces pilot pressure into the oil chamber of at least one of the centering pistons are provided between the main spool and the main spool, and the main spool is of a hydraulic pilot-driven type that moves following the centering piston, and the electromagnetic switching valve A proportional electromagnetic directional flow control valve characterized in that it switches and introduces pilot pressure in a predetermined case.