JPS5833949B2 - Force feedback type solenoid pilot type switching valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention reduces the pressure supplied from a pressure fluid source to an actuator by controlling the pilot pressure fluid supplied to each pilot chamber at both ends of the switching spool through a restriction and moving the switching spool. This invention relates to a feedback type electromagnetic pilot type switching valve that controls the direction and amount of fluid supplied.

Conventionally, as this type of switching valve, there is a nozzle flappe type switching valve disclosed in Japanese Patent Application Laid-Open No. 5015978.

As shown in FIG. 4, this switching valve includes a permanent magnet torque motor 50 having a movable armature member, a movable control member 51 connected to the movable armature member, and a movable control member 51 connected to the movable armature member.
1 and the valve spool 5
4, left and right end chambers 55, 56 provided at both ends of the valve spool 54 and connected to the nozzles 52 and 53, respectively, and a movable control member for feeding back the amount of movement of the valve spool 54 to the movable armature member. The feedback spring member 57 is connected to the feedback spring member 51 and the like.

When the movable armature member of the permanent magnet torque motor 50 is actuated in response to a command, the movable control member 51 moves to control the amount of pilot pressure fluid discharged from the nozzles 52 and 53, thereby controlling the left end chamber 55 and the right end chamber. A pressure difference is created between the chambers 56 and the valve spool 54 is switched.

When the release valve spool 54 moves to a predetermined switching position,
The amount of movement is fed back to the movable control member 51 by the feedback spring member 57, which controls the amount of pilot pressure fluid discharged from the nozzles 52, 53 to maintain a constant pilot pressure difference between the left and right end chambers 55, 56. to hold the valve spool 54 in the predetermined switching position.

Also, the permanent magnet torque motor 50 is demagnetized and the valve spool 5
4 is in the neutral position, the valve spool 54 is held in the neutral position by simultaneously discharging the amount of pilot pressure fluid from the nozzles 52 and 53.

However, in the conventional device described above, pilot pressure fluid continues to be discharged from the nozzle not only when the valve spool is in the neutral position but also in any switching position, resulting in a large amount of pilot pressure fluid being consumed. There was a problem.

The cause of this problem is that the pilot pressure fluid in both pilot chambers is constantly discharged from both nozzles, and the permanent magnet torque motor is activated by command to move the movable control member to suppress the discharge amount from one nozzle and By increasing the amount of discharge from the nozzle, a pressure difference is created between the two pilot chambers, so it can be used under any conditions, such as when switching the valve spool, as well as when maintaining the desired switching position. This is because the flow rate of the pilot pressure fluid discharged from both nozzles does not change even when the pilot pressure fluid is discharged, and a constant amount of pilot pressure fluid continues to be discharged.

In view of the above-mentioned problems, the present invention discharges only the pilot pressure fluid from one pilot chamber when a command is received, creates a pressure difference between both pilot chambers, and throttles and controls the discharge amount of the pilot pressure fluid. The technical problem is to suppress the amount of pilot pressure fluid discharged by keeping the pressure difference between both pilot chambers constant.

A means for solving this technical problem is to provide each pilot chamber with a spool-type electromagnetic pilot valve that controls opening and closing of the pilot pressure fluid outlet of each pilot chamber at both ends of the switching spool, facing the switching spool ends. Feedback springs are interposed between each of the spool-type electromagnetic pilot valves and each end of the switching spool.

By adopting this means, when there is no command, the solenoid pilot valve is closed by the feedback spring and does not discharge the pilot pressure fluid.

Then, only when a command is received, one of the solenoid pilot valves is opened to discharge the pilot pressure fluid, creating a pressure difference between both pilot chambers, and moving the switching spool. Feedback to the valve narrows the opening of the electromagnetic pilot valve to balance the electromagnetic force, throttles and controls the discharge amount of pilot pressure fluid, holds the switching spool in its switching position, and suppresses the discharge amount of pilot pressure fluid. There is.

In this way, the consumption can be reduced by controlling the discharge of the pilot pressure fluid with the minimum amount of discharge when necessary.

In order to solve the above technical problem, a poppet type electromagnetic pilot valve may be used instead of the spool type electromagnetic pilot valve.

However, in this poppet type, in order to maintain the pressure in the pilot chamber at a predetermined pressure, the pilot valve operates slightly in response to slight pressure fluctuations in the pilot chamber.
The pressure in the pilot chamber is maintained at a predetermined level by controlling the amount of pilot pressure fluid discharged from the pilot chamber, but when the pilot valve makes slight movements, the poppet-type pilot valve hits the valve seat and generates noise. , so-called chuckling phenomenon is likely to occur.

In contrast, the spool type pilot valve of the present invention simply slides (slight movement) in its axial direction even if a slight pressure fluctuation occurs in the pilot chamber.
It has the unique effect of not hitting the valve seat and producing no sound.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 3.

A switching spool 7 is slidably inserted into the switching valve body 1, and when the switching spool 7 moves from the neutral position to the left, for example, the pressure fluid flows through the supply path 2, the seat hole 22,
Load check valve 21. It is supplied to the actuator via the supply path 23, the actuator passage 6', and the connection port 5',
The supply amount is controlled by the amount of movement of the switching spool 7.

At this time, fluid is discharged from the actuator through the connection port 5, the actuator passage 6, the discharge passage 3, and the tank passage 4.

Furthermore, when the switching spool 7 moves from the neutral position to the right, the pressure fluid flows through a path opposite to that described above.

That is, the pressure fluid is supplied to the supply path 2, the seat hole 22, the load check valve 21, the supply path 23, and the actuator path 6.
, the fluid is supplied to the actuator through the connection port 5, and fluid is discharged from the actuator through the connection port 5', the actuator passage 61, the discharge path 3', and the tank passage 4.

Pilot parts 8, 8' are attached to both sides of the switching spool 7 of the switching valve body 1, and pilot chambers 25, 25' are provided inside each part.

In these pilot chambers 25, 25', return springs 10, 10' for returning the switching spool 7 to the neutral position are provided between the left and right ends of the switching spool 7 and the inner wall of each pilot chamber 25, 25'. .

Reference numerals 9 and 9' denote spring supports for return springs 10 and 10', which are fitted to the left and right ends of the switching spool, respectively.

Further, spool-type pilot valves 12 and 12' are arranged opposite to the left and right ends of the switching spool, and feedback springs 11 and 1 are disposed between one end of these and the spring receivers 9 and 9'.
1' is placed.

Reference numerals 13 and 13' designate spring receivers that fit into one ends of the pilot valves 12 and 12'.

The pilot valve 12.12' is connected to the pilot supply line 24,
24' to the pilot chamber 2 via the throttle 30 and 30'.
5, 25' acts to throttle the discharge passages 26, 26' for discharging the pilot pressure fluid supplied to the pilot pressure fluid.

These discharge passages 26 and 26' are drain passages 27° and 27'.
is connected to.

A solenoid 1 is installed at the other end of the pilot valve 12, 12'.
7.17' is arranged, and its coils 16, 16'
The movable iron cores 14, 14' move according to the electromagnetic force of
5, controls the discharge of pressure fluid in 25'.

15, 15' are fixed iron cores excited by coils 16, 16', 2B, 28' are pilot valves 12,
A valve hole is provided at 12', and 29 and 29' are valve ports.

Next, the operation of the electrode pilot type switching valve shown in FIG. 1 will be explained.

When the switching spool 7 is in the neutral position shown in FIG.
, 26' are completely shut off by the pilot valves 12, 12', so the pilot supply paths 24, 24'
The pressing forces acting on the left and right ends of the switching spool 7 are balanced by the pressure fluid supplied to the pilot chambers 25 and 25' through the spool.

In addition, the pilot chambers 25 and 25' are connected to the pilot valve 12.
, 12', the pilot room 25
, 25', the switching spool 7 is maintained at the neutral position by the return springs 10, 10' even if the fluid pressure in the pilot chambers 25, 25' disappears due to pressure loss in the flow paths up to the pilot chambers 25, 25'.

Further, even if the fluid pressures in the pilot chambers 25, 25' are different, the pressing force acting on the switching spool 7 due to this difference in fluid pressure is smaller than the pressing force by the return springs 10, 10'.

Therefore, the pilot chambers 25 and 25' are connected to the pilot valve 1.
2, 12', the switching spool 7 is held in the neutral position.

Next, for example, when an exciting current is applied to the coil 16 of the solenoid 17, the fixed iron core 15 is excited, the movable iron core 14 is attracted, and the pilot valve 12 is pushed to the right against the feedback spring 11. , the pilot valve 12 moves to the right, the valve port 29 and the discharge passage 26 communicate with each other, and the fluid pressure in the pilot chamber 25 begins to decrease.

On the other hand, since the fluid pressure in the pilot chamber 25' remains at the supply fluid pressure, the pilot chambers 25, 2
A pressing force due to the fluid pressure difference in the switching spool 5' acts on the switching spool 7, and this pressing force overcomes the return force of the return spring 10, and the switching spool 7 begins to move to the left.

When the switching spool 7 begins to move leftward, the tension of the phytovac spring 11 also increases, and the force pushing the pilot valve 12 to the left increases due to the tension.

The pilot valve 12 moves to a position where the pressing force received from the feedback spring 11 and the suction force acting on the movable iron core 14 are balanced, and the switching spool I is moved to a position where the pressing force received from the feedback spring 11 and the suction force acting on the movable iron core 14 are balanced. It stops at a position where the pressure and the pressing force of the return spring 10 are balanced.

In this way, the switching spool 7 stops at a position corresponding to the value of the excitation current supplied to the coil 16.

As is clear from this series of operations, the pilot valve 12 and the movable iron core 14 are hardly displaced by the feedback action of the feedback spring 11.

Therefore, the solenoids 17, 17' may be of any type without being limited by the characteristics of the stroke and suction force of the movable iron core.

In other words, even if a solenoid with non-linear characteristics (normal on/off solenoid) is used, the amount of movement of its movable iron core will be within an extremely small range, so the attractive force acting on the movable iron core will not be converted into the excitation current flowing through the coil. It can be made almost proportional.

Therefore, even if a normal on/off solenoid, which has a simple structure and is inexpensive, is used as the solenoid 17°17', the movable iron core 14
, 14' is approximately proportional to the excitation current flowing through the coils 16, 16', so the switching spool 7 is
As described above, the position is controlled in proportion to the excitation current flowing through the coils 16, 16'.

Note that when the characteristics of the solenoid are linear, the same applies as described above.

Here, if the electromagnetic part is excited by a pulse current modulated in pulse width, it is possible to provide a dithering effect against hysteresis, which is a problem when using a plunger type solenoid, and the fluid sticking phenomenon peculiar to hydraulic switching valves. .

Next, when positioning the switching spool 7 by moving it to the right, the coil 16' of the solenoid 17' is
, and its operation is the same as described above, so a description thereof will be omitted.

[Brief explanation of drawings]

1 and 2 are vertical cross-sectional views showing the internal structure and enlarged main parts of one embodiment of the electromagnetic pilot type switching valve according to the present invention, and FIG. 3 is a longitudinal sectional view of the switching valve shown in FIG. 1. FIG. 4, a block diagram showing the operation, is a schematic diagram showing a conventional nozzle flapper type switching valve. 5, 5'... Actuator end connection, 7...
...Switching spool, 10, 10'...Return spring, i1. i i'... Feedback spring, 12, 12'... Pilot valve, 14
, 14'...Movable iron core, 16, 16'...
...Coil, 17,17'...Solenoid (
Electromagnet) 25, 25'...Pilot room, 2
6, 26'... discharge passage, 30, 30'...
...Aperture.

Claims (1)

[Claims] 1. By controlling the pilot pressure fluid supplied to each pilot chamber at both ends of the switching spool via a throttle and moving the switching spool, the direction and amount of pressure fluid supplied from the pressure fluid source to the actuator is controlled. In the copper feedback type electromagnetic pilot type switching valve, a spool type electromagnetic pilot valve for controlling the opening and closing of the pilot pressure fluid outlet of each of the pilot chambers is provided in each pilot chamber so as to face the switching spool end, and each of the spools A feedback type electromagnetic pilot type switching valve characterized in that a feedback spring is interposed between the type electromagnetic pilot valve and each end of the switching spool.