JPH0423125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position-following proportional solenoid type spool valve that controls the flow rate of oil according to the magnitude of an input current that excites a solenoid.

[Conventional technology]

As a conventional proportional solenoid type spool valve,
For example, there is one shown in FIG.

In this spool valve, a spool 3 is slidably provided in a sliding hole 2 formed in a body 1, and is moved through washers 8 and 9 by springs 6 and 7 provided in spring chambers 4 and 5 on both sides, respectively. The lever spool 3 is pressed and held in the illustrated position when the valve is closed.

The body 1 is further provided with an oil inlet 10 and an oil outlet 11, and an annular groove 12 following the oil outlet 11. In the illustrated closed state, the land portion 3a of the spool 3 moves the annular groove 12. is closed to block the inflow port 10 and the outflow port 11.

When a sealed proportional solenoid 13 fixed to one end of the body 1 is energized, the movable iron core 14 moves to the left according to the magnitude of the input current, and the spool 3 is moved to the left by the push rod 14a. move it.

As a result, a flow path from the inlet 10 to the outlet 11 of the body 1 is opened, and oil flows at a flow rate corresponding to the magnitude of the input current.

In the case of such a proportional solenoid type spool valve, the spool 3 in the fully closed state is
The sealing width X ₀ between the annular groove 12 and the annular groove 12 is required to be an appropriate amount to prevent fluid leakage.

There is also a position-following proportional solenoid type spool valve operated by a pilot as shown in FIG. Note that in FIG. 8, parts corresponding to those in FIG. 7 are given the same reference numerals.

This spool valve uses a nozzle flapper mechanism, and has a control oil chamber 15 formed in the front end of the land portion 3b of the spool 3, that is, the right end of the sliding hole 2, and one end of the spool 3 (the land portion 3b side)
A nozzle 3c is provided in a protruding manner and protrudes into a nozzle flapper chamber 16 through a seal wall 1a provided on the body 1, and the spool 3 is pressed in one direction (rightward in the figure) by a spring 6.

In the nozzle flapper chamber 16, a flapper 17 fixed to the tip of the push rod 14a of the movable core 14 of the proportional solenoid 13 is arranged opposite to the tip of the nozzle 3c at a small distance, and is engaged between the seal wall 1a. The spring 18 provides an urging force that resists the pressing force of the proportional solenoid 13.

Then, the pilot oil introduced into the control oil chamber 15 from the pilot oil supply port 19 via the orifice 19a is caused to flow out from the gap between the tip of the nozzle 3c and the flapper 17 through the oil passage 3d in the nozzle 3c, and is then controlled by the pilot oil pressure. A force is applied to press the spool 3 to the left.

On the other hand, pilot oil is also introduced into the oil chamber 20 formed at the left end of the sliding hole 2 by the small diameter portion 3e connected to the land portion 3a on the spring chamber 4 side of the spool 3 through the oil passage 19b. In addition to the biasing force of the spring 4, this pilot hydraulic pressure also pushes the spool 3 to the right.

Then, when the proportional solenoid 13 is energized from the illustrated state, the push rod 14a moves to the left against the spring 18, and the flapper 17 moves toward the nozzle 3c.
As a result, the pressure inside the control oil chamber 15 increases, and the spool 3 is pushed to the left and moves to the left against the spring 4 and the pilot oil pressure in the oil chamber 20, causing the annular groove 12 to close. open.

Therefore, the flow rate of oil flowing from the inlet 10 to the outlet 11 is controlled by the input current that excites the proportional solenoid 13.

Proportional solenoid type spool valves like this are driven by pilot hydraulic pressure, so the spool can be powerfully driven with a small proportional solenoid, but a seal width of X ₀ is still required to prevent fluid leakage when the valve is fully closed. It is.

[Problem that the invention seeks to solve]

In such conventional proportional solenoid type spool valves, the displacement characteristics of the proportional solenoid with respect to the spring load are different depending on whether the spool is displaced forward or backward.
As shown in FIG. 9, a displacement difference (hysteresis) occurs between the forward movement of the spool (when the valve is opened) and the backward movement (when the valve is closed) for the same input current.

In particular, since the oil flow path is blocked while the spool is displaced by the seal _width In addition to narrowing the flow rate control range, there was a problem in that the hysteresis of the spool displacement was particularly large in the small flow rate area near this area, as shown in FIG.

This invention solves these conventional problems and reduces the width of the dead band for input current, reduces the hysteresis when opening and closing the valve, and enables stable flow control over a wide control range. The purpose is to ensure that

[Means for solving problems]

Therefore, the position-following type proportional solenoid type spool valve according to the present invention is a pilot-operated proportional solenoid type spool valve using a nozzle flapper mechanism as shown in FIG. A first spring with a small spring constant that acts in a small output range of the proportional solenoid and a second spring with a large spring constant that acts in a higher output range of the proportional solenoid are provided as springs that bias the proportional solenoid. It is.

[Effect]

By doing this, in the small output range where the input current of the proportional solenoid is small, the flapper is largely displaced in the direction toward the nozzle against the weak biasing force of the first spring, and the spool also follows it. With a large displacement, the valve opens beyond the aforementioned seal width X ₀ . After that, the strong biasing force of the second spring acts, so the relationship between the input current of the proportional solenoid, the displacement of the spool, and the flow rate becomes as shown in Figures 2 and 3, and the dead zone becomes extremely small, and the valve Hysteresis during opening and closing is also reduced.

〔Example〕

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

FIG. 1 is a longitudinal cross-sectional view of a position-following proportional solenoid type spool valve showing an embodiment of the present invention, and parts corresponding to those in FIG. 8 are given the same reference numerals.
Their explanation will be omitted.

In this spool valve, a flanged bottomed cylindrical flapper 21 is integrally fitted to a push rod 14a of a proportional solenoid 13 that projects into a nozzle flapper chamber 16 formed in a body 1. The nozzle 3c is arranged so as to face the nozzle 3c at all times with a small gap ΔX ₀ in between.

Further, a cylindrical spring receiver 22 having a stepped flange is slidably fitted into the flapper 21, and a spring constant of A small first spring 23 is interposed.

Furthermore, the flange 22b of the spring receiver 22
A second spring 24 having a large spring constant is interposed between the second spring 24 and a disk-shaped spring receiver 25 provided on the nozzle flap chamber 16 side of the seal wall 1a through which the nozzle 3c is inserted.

These first and second springs 23 and 24 are both springs that apply a biasing force to the flapper 21 that resists the pressing force by the proportional solenoid 13.

In the state shown in FIG. 1, the solenoid 13 is not energized, the flapper 21 is pushed back by the urging forces of the first and second springs 23 and 24 and is at the right-hand end position, and the spool 3 is , the pressing force of the spring 6 and the pilot oil pressure P _p push the end face of the area A ₁ on the oil chamber 20 side of the land portion 3a to the right, and the pilot oil pressure of the control oil chamber passing through the orifice 19a is applied to the land portion. Area of 3b A ₂
(A ₂ = A ₁ × 2) Due to the balance with the leftward pressing force that pushes the end face, the annular groove 12 leading to the outlet 11
is closed with seal width x ₀ and is in a fully closed state.

At this time, the distance Y ₀ between the facing surfaces of the flange 21 a of the flapper 21 and the flange 22 b of the spring receiver 22 is set to be equal to the sealing width X ₀ between the spool 3 and the annular groove 12 .

When the proportional solenoid 13 is energized from this state, in the small output range where the input current I is small, the flap 2 is caused by the pressing force of the push rod 14a.
1 moves to the left while compressing only the first spring 23, and following this, the spool 3 also moves to the left by the pilot oil pressure.

For example, when the input current I of the proportional solenoid 13 becomes 5% of the current when fully open, the flapper 21
The flange 21a of the spring receiver 22 contacts the flange 22b of the spring receiver 22, and the spool 3 has a seal width of X ₀ (X ₀
= Y ₀ ) to the left and begin to open the annular groove 12.

Then, the input current I of the proportional solenoid 13 is 5
In the power range of % or more, as the power increases,
The flapper 21 is engaged with the spring receiver 22 and moves to the left while compressing the second spring 24, and the spool 3 follows it and moves to the left.
The annular groove 12 is gradually opened larger, and the flow rate Q of oil flowing from the inlet 10 to the outlet 11 increases.

In other words, the input power I to the proportional solenoid 13
In the small output range where is less than 5%, the flapper 21
Since only the first spring 23 with a small spring constant (weak) acts as _a biasing force against the movement of Seal width as shown in Figure 2
It can be moved by X ₀ , and the hysteresis is also small in this small output range.

The flow characteristics in this case are as shown in Fig. 3. In the dead zone, the input current I of the proportional solenoid 13 is extremely small, 0 to 5%, and the valve opens from the low input current range and the flow rate control is performed. As is clear from a comparison with FIG. 10, the hysteresis in the low flow rate region becomes extremely small.

Next, another embodiment of the present invention will be described with reference to FIG. Note that parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and their description will be omitted.

In this embodiment, the large-diameter annular stepped portion 31a
and a flange 3 formed with a small-diameter annular step portion 31b.
1c, the flapper 31 is connected to the proportional solenoid 13.
A large-diameter annular stepped portion 35a is fitted onto the push rod 14a, and is also provided on the disc-shaped spring receiver 35 through which the nozzle 3c is inserted and which is in close contact with the seal wall 1a.
and a small-diameter annular step portion 35b.

A first spring 33 having a small spring constant is interposed between the step portion 31a of the flapper 31 and the step portion 35a of the spring receiver 35, and the first spring 33 is placed inside the first spring 33.
A second spring 34 with a larger spring constant,
It is disposed apart from the stepped portion 31b of the flapper 31 by a gap _Y0 equal to the seal width _X0 , and one end is engaged with the stepped portion 35b of the spring receiver 35.

In this way, as in the previous embodiment, in a small output range where the input current I of the proportional solenoid 13 is, for example, 5% or less, the stepped portion 31b of the flapper 31 will not come into contact with the second spring 34. Since the flapper 31 moves to the left while compressing only the first spring 33 with a small (weak) spring constant, the spring load on the proportional solenoid 13 is small, and the spool 3 follows the flapper 31 to the sealing width.
X Moves with a small output for ₀ minutes and begins to open the valve.

Then, the input current I of the proportional solenoid 13 is 5
% or more, the stepped portion 31b of the flapper 31
engages with the second spring 34 having a large (strong) spring constant and moves to the left in accordance with the output of the proportional solenoid 13 while compressing it, and the spool 3 also follows and moves to the left. and gradually increase the flow rate Q.

Therefore, the input current I of the proportional solenoid 13
The characteristics of the displacement X of the spool 3 and the output flow rate Q with respect to the flow rate are the same as those shown in FIGS. 2 and 3, and the same effects as in the embodiment shown in FIG. 1 can be obtained.

FIG. 5 shows a directional control valve constructed by symmetrically providing a nozzle flapper mechanism similar to the embodiment shown in FIG. 1 on both sides of a spool valve. The same reference numerals are used to omit their description.

In this embodiment, from the illustrated neutral (closed) state, the proportional solenoid 1 provided at both ends of the body 41
By driving either one of the flappers 3 and 13, one flapper 21 is moved in a direction approaching one of the nozzles 43c and 43c protruding from both ends of the spool 43, and the spool 43 follows this movement. By moving, the land portions 43a, 43
The ports A and B formed on the body 41 are switched to the ports P and T by the port 41 and communicated with each other by the port b.

Oil passages 43d are formed in the nozzles 43c protruding from both ends of the spool 43, and the nozzle flapper chambers 16 on both sides are connected to the oil passages 43d.
3d to communicate with the tank port (port T), and pilot oil is introduced from the pilot oil supply port 19 through orifices O ₁ and O ₂ , respectively, so that it also serves as the control oil chamber 15 in Fig. 1. I'm letting you do it.

In addition, between each nozzle 43c and the flapper 21 attached to the push rod 14a of the proportional solenoid 13, there is provided a sliding allowance for the spool 43.
In the illustrated neutral state, a gap Z is provided which is considerably larger than ΔX ₀ in each case.

A first spring 23 with a small spring constant is interposed between the flange of each flapper 21 and the inner step of the slidable spring receiver 22, and a first spring 23 with a small spring constant is interposed between the flange of the spring receiver 22 and the spring receiver 25. This embodiment is similar to the embodiment shown in FIG. 1 in that a second spring with a large spring constant is provided.

Here, the gap Y ₀ between the facing surfaces of the flange of each flapper 21 and the flange of the spring receiver 22 is
Seal width X ₀ between the spool 43 and the annular groove for ports A and B, the nozzle 43c in the neutral state described above
_The relationship is _{Y 0 =} This is different from the embodiment shown in FIG. 1 in that it is set as follows.

Note that the outermost springs 46 in the nozzle flapper chambers 16 at both ends are the springs 6 in FIG.
This is a spring that presses the spool 43 corresponding to the spool 43 in one direction.

In this example, the right solenoid 13
(SOL A), for example, its input current I
When it becomes 5% or more, ports B and P and ports A and T are connected to each other, as shown in Fig. 6.
Oil flows from port P to B at a flow rate QB according to input current I.

On the other hand, when the left solenoid 13 (SOL B) is energized and its input current I becomes 5% or more, ports A and P and ports B and T are connected, respectively, as shown in Figure 6. Oil flows from port P to A at a flow rate QA that corresponds to the magnitude of input current I.

In this embodiment as well, the dead zone when energizing one of the proportional solenoid 13 to open the valve from the neutral (valve closed) state is reduced, and the hysteresis in the small flow rate region is also reduced.

In the above embodiment, the first spring is compressed in a small output range of 5% or less of the input current of the proportional solenoid, but the spring constant and the spring constant of the first spring can be changed as appropriate depending on the seal width. By simply changing the length, the dead zone can be kept at most 10% or less.

〔Effect of the invention〕

As explained above, the position-following type proportional solenoid type spool valve according to the present invention has a nozzle
The spool is slid using a flapper mechanism, but
A spring that applies an urging force to the flapper that resists the pressing force of the proportional solenoid is composed of a first spring with a small spring constant and a second spring with a large spring constant, and in the small output range of the proportional solenoid. Since only the first spring with a small spring constant acts, the spring load on the proportional solenoid in the small output range is small, and the spool can be slid by the seal width at a small output, making it possible to The dead zone can be made smaller. In addition, the hysteresis in the small flow rate region is reduced, and the characteristics when the valve is open and when the valve is closed are almost the same.

Therefore, it is possible to perform stable flow rate control according to the input current over a wide control range, and when the valve is fully closed, the seal width is increased to completely prevent leakage.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a position-following type proportional solenoid type spool valve showing one embodiment of the present invention, and FIG.
3 and 3 are characteristic curve diagrams showing the relationship between the spool displacement and the output flow rate with respect to the input current of the proportional solenoid according to the embodiment of FIG. 1, respectively, and FIGS. FIG. 6 is a longitudinal sectional view similar to FIG. 1 showing a different embodiment.
6 is a characteristic curve diagram showing the output flow rate characteristics with respect to the input current of each proportional solenoid according to the embodiment of FIG. 5. FIG. 7 and 8 are longitudinal cross-sectional views showing different examples of conventional proportional solenoid type spool valves, and FIGS. 9 and 10 respectively show the spool for the input current of the proportional solenoid by the spool valve of FIG. 8. FIG. 3 is a characteristic curve diagram showing the relationship between displacement and output flow rate. 1,41...Body, 3,43...Spool,
3c, 43c... Nozzle, 10... Inflow port, 11
... Outlet, 12 ... Annular groove, 13 ... Proportional solenoid, 14a ... Push rod, 16 ... Nozzle flap chamber, 19 ... Pilot oil supply port, 21, 31 ... Flutter, 22 ... Sliding Flexible spring receiver, 23, 33...first spring, 24, 34...second spring, 25,
35...Disc-shaped spring receiver.

Claims (1)

[Claims] 1. A spool that opens and closes an oil inlet or an oil outlet is slidably provided in a sliding hole formed in the body,
The spool is pressed in one direction by the force of a spring or pilot oil pressure, and a nozzle protruding from one end of the spool and a flapper attached to the push rod of the proportional solenoid are placed opposite each other, and the nozzle and flapper are connected through an orifice. In the position-following proportional solenoid type spool valve, the spool is displaced to follow the flapper by applying a pressing force in the opposite direction to the pressing force to the spool by pilot oil pressure introduced between the flaps, a first spring with a small spring constant that acts in a small output range of the proportional solenoid, and a first spring that applies a biasing force against the pressing force of the proportional solenoid; 1. A position-following proportional solenoid type spool valve, characterized in that a second spring having a large spring constant is provided.