JPH0234708B2 - YUATSUKAIROYONORYURYOCHOSEIBEN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flow rate regulating valve for a hydraulic circuit suitable for regulating the flow rate of a hydraulic circuit such as a die-casting machine.

[Prior Art] Generally, a die casting machine performs injection at a low speed at the initial stage of molten metal injection by an injection cylinder, and switches to high speed injection during injection to supply the molten metal into a mold cavity. The hydraulic circuit of a die casting machine that performs such an operation uses a switching valve that switches from low-speed injection to high-speed injection, and a flow rate adjustment valve for low-speed injection and high-speed injection that adjusts the flow rate of hydraulic oil.

Conventionally, as shown in FIG. 6, which is also known in Japanese Patent Publication No. 55-37338, the injection circuit has been provided with an on-off valve 56 and a flow rate regulating valve 57 for low-speed injection, and an on-off valve 56a for high-speed injection. Flow rate adjustment valve 57
Four pieces of a were used.

In Fig. 6, 35 is an injection cylinder, 42 is a hydraulic pump, 53 is an accumulator, 54 is a switching valve for forward and backward movement of the injection cylinder 41a, and 55 is a check-type shut-off valve 56 and a throttle valve 57 integrated into one body. A valve for low-speed injection; 58 is a switching valve for low-speed injection; 55a is a valve for high-speed injection that integrates a check-type shutoff valve 56a and a throttle valve 57a; 58a is a switching valve for high-speed injection;
9 is a changeover valve for run-around, 60 is a relief valve for setting the pressure of the accumulator 53, 61 is a check valve, and the throttle valves 57 and 57a are each opened and locked in advance to the required opening degree. ,
Shutoff valves 56, 56 are opened and closed for each cycle.
They each went to a.

In the hydraulic circuit diagram shown in FIG. 6, the switching valve 58 for low-speed injection is switched to open the shut-off valve 56, and the injection cylinder is operated at a low speed corresponding to the opening degree of the throttle valve 57, which has been opened to a predetermined opening degree. 35, the piston rod 35a is advanced. Also, during injection, the switching valve 58a for high-speed injection is switched to open the shutter-off valve 56a, and the piston rod 35a of the injection cylinder 35 is operated at a high speed according to the opening degree of the throttle valve 57a, which has been opened to a predetermined opening degree. advance.

On the other hand, as is known from Japanese Patent Publication No. 46-7412, for example, there is a flow control valve 69 for a hydraulic servo device shown in FIG. 7.

The flow rate control valve 69 shown in FIG.
In the valve body 72, left and right spools 72a, 72b are connected by a shaft 72c. The flow rate control valve 69 has a special rotary type nozzle flapper mechanism (not shown) in the valve box 73, and the nozzle flapper mechanism is connected to the movement of the valve body 72 via a gear device 71a. Open and close. Reference numerals 74a and 74b are check valves that release the back pressure of the nozzle flapper mechanism as pilot oil, and when the valve body 72 reaches the neutral position, the nozzle flapper mechanism is expanded and the check valves 74a and 74b are rapidly closed, and the pressure oil is released. It is designed to completely lock the lock and prevent hunting.

[Problems to be Solved by the Invention] In the injection circuit as shown in FIG. Since the injection circuit and structure were complicated, and the flow rate regulating valves 57 and 57a were also commonly used rotary slide valves and spool valves, the response speed of valve opening and closing was slow. It was also relatively slow.
In addition, these conventional flow rate regulating valves 57, 57a have only one constriction part between the oil supply side and the oil outflow side, that is, the part through which oil flows when the valve is opened, so the valve diameter is large. As a result, the entire flow rate regulating valve has become larger, and the installation area required to install all the valves including the on-off valves 56, 56a, etc. has also become larger.

On the other hand, in the flow control valve 69 of the hydraulic servo device shown in FIG.
etc., so the structure is not only complicated, but also the response speed is relatively slow.

Moreover, this valve body 72 is connected to the left and right spools 72.
a, 72b are connected by the shaft 72c, the areas of the right surface of the left spool 72a and the left surface of the right spool 72b are the same, and the valve body 72 moves, for example, to the right in the figure, and the flow path 73a opens. When communicating with the flow path 73b, oil enters from the flow path 73a at right angles to the axis of the valve body 72 and exits at right angles to the flow path 73b.

In this case, on the oil outlet side, the flow rate of oil increases at the outlet and the pressure decreases accordingly, so the average pressure acting on the right side of the left spool 72a is equal to the average pressure acting on the left side of the right spool 72b. becomes relatively larger, and as a result, the valve body 72 has a
A thrust force F ₂ is applied in the left direction, that is, in the direction of closing the valve body 72 due to the action of oil.

Therefore, when the valve body 72 is moved to the right to start flowing oil from the flow path 73a to the flow path 73b, the brake must be applied to the valve body 72 in the valve closing direction from the time when the valve starts opening. A force F ₂ similar to that applied thereto begins to act, and this force F ₂ increases as the valve body 72 moves in the valve opening direction. As a result, the movement of the valve body 72 and the attempt to open the valve is delayed accordingly, resulting in a relatively long valve opening time. However, valve body 7
2 moves significantly to the right and the outlet section becomes larger, from a certain point the difference between the pressure acting on the right side of the left spool 72a and the pressure acting on the left side of the right spool 72b, and the oil In balance with the magnitude of the force colliding with the left side, the force F ₂ acting in the valve closing direction begins to become a little smaller.

For reference, the flow rate Q, flow velocity, or valve opening in this case, and the force _F2 acting in the valve closing direction.
The relationship between the two is shown in FIG.

When the valve body 72 reaches the valve opening limit and is kept at that position, a relatively large force F 2 continues to act on the valve body 72, so a relatively large force F ₂ continues to act on the valve body 72. Body retention is required.

Therefore, even if such a flow rate regulating valve 69 is used in the injection circuit of a die-casting machine, satisfactory injection speed control cannot be achieved.

This is because in die casting machines, in order to obtain good injection conditions and high quality injection products,
For example, from low speed of 0.1~0.2m/sec to 1~5m/sec
This is because it is necessary to increase the speed to a high speed within an extremely short time, such as about 0.05 seconds, and to obtain a predetermined high speed with high accuracy. A flow control valve is required that allows oil to flow all at once.

[Means for Solving the Problems] In order to solve such problems, the present invention provides four valves: an on-off valve and a flow rate adjustment valve for low-speed injection, and an on-off valve and a flow rate adjustment valve for high-speed injection. The flow rate adjustment valve is combined into one flow rate adjustment valve, and the throttle portion of this flow rate adjustment valve is provided at two or more locations in the axial direction of the valve, so that the valve diameter can be reduced.

Furthermore, in the present invention, when the valve spool starts to shift from low speed to high speed as the valve spool opens,
The thrust force acting on the valve spool acts in the direction of opening the valve spool, and when the valve spool reaches a predetermined high speed and stops, the thrust force acting on the valve spool acts in the direction of closing the valve spool.
The valve spool is effectively assisted in stopping the valve spool so that the valve spool is stopped quickly and reliably, and the thrust force acting on the valve spool can be changed in accordance with the opening operation of the valve spool. Furthermore, when the valve spool is held in place, the thrust force is relatively small so as not to put too much stress on the mechanical holding device.

Therefore, in the present invention, in the flow rate regulating valve 1 for a hydraulic circuit in which the valve spool 31 is slidably provided in the valve chamber 30 of the manifold 29, an inlet 29b is provided at one end side in the axial direction of the valve chamber 30, Valve chamber 30
Two or more annular circulation holes 33, 34 forming part of the outlet are provided in a direction perpendicular to the axis of A valve spool 31 is provided so as to be slidable in the axial direction so that the communication holes 33 and 34 can be opened and closed on the outer peripheral surface of the valve spool 31. It is divided into a first chamber 30a and a second chamber 30b on the opposite side to the side where the inlet 29b is located, and a valve shaft 28 extending to the outside of the second chamber 30b is attached to the axial center of the valve spool 31 on the second chamber 30b side. A screw mechanism 17,1 is provided to change the tip of the valve shaft 28 from rotational movement to axial movement.
The valve spool 31 is connected to the motor 6 via 7a and 19, and has a large number of through holes 31a and 31b that penetrate in the axial direction inside the valve spool 31, and is isolated from the outside except for the through holes 31a and 31b. 2nd room 30b
and the first chamber 30a, and an annular groove 3 that communicates with the through holes 31a and 31b on the outer peripheral surface part of the valve spool 31 in the axial direction.
2, the first chamber 30a and the annular circulation hole 3 are provided.
3 and 34 directly and indirectly through the through holes 31a and 31b and the annular groove 32,
The structure is such that the valve spool 31 is provided at two or more locations in the axial direction.

[Function] When the motor 6 is slightly rotated in the valve opening direction with the outer peripheral surface of the valve spool 31 closing two or more annular circulation holes 33 and 34, the rotational movement is changed to an axial movement. Screw mechanism 17, 17a, 1
9, the valve spool 31 slides a little in the valve opening direction, one of the two or more communication holes 33, 34 opens a little, and the hydraulic oil flows from the inlet 29b in the axial direction of the valve chamber 30 to the axis of the valve chamber 30. The communication hole 33, 3 in the direction perpendicular to
4, and is supplied from the outlet 29c to, for example, the injection cylinder 35.
The piston rod 35a of the piston rod 35a is advanced at low speed.

When the piston rod 35a of the injection cylinder 35 moves forward by a predetermined stroke at low speed, the motor 6
If you give a command pulse signal to switch to high-speed injection,
The valve spool 31 moves by a predetermined amount in the valve opening direction, and the hydraulic oil flows into the two or more communication holes 33 and 34, causing the piston rod 35a of the injection cylinder 35 to advance at high speed.

In this case, the flow rate regulating valve 1 of the present invention can easily perform low-speed injection and high-speed injection operations and adjust their injection speeds with one valve. By providing two or more flow holes 33, 34, a large amount of hydraulic oil can flow at once using a relatively large-diameter flow rate regulating valve.

Furthermore, in the present invention, as will be explained in detail in the embodiment section below, when the valve opening operation of the valve spool 31 starts to shift from low speed to high speed,
When the thrust force acting on the valve spool 31 acts in the opening direction of the valve spool 31 and reaches a predetermined high speed and the valve spool 31 stops, the valve spool 3
The thrust force acting on the valve spool 31 acts in the direction in which the valve spool 31 closes, effectively assisting in stopping the valve spool 31, and the valve spool 31 is quickly and reliably stopped. Moreover, when the valve spool 31 is kept in a predetermined position, the thrust force becomes relatively small.
It does not put too much stress on the mechanical holding device.

Therefore, the flow rate regulating valve 1 of the present invention allows the transition from low speed to high speed to be performed extremely quickly, reliably and easily, and exhibits high precision.

[Example] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

Figures 1 to 3 explain one embodiment of the present invention. As shown in Figure 1, a flow rate adjustment valve 1 is roughly divided into a drive unit 2 located at one end and a flow rate adjustment valve that also functions as an on-off valve. It consists of Section 3.

The drive unit 2 has a motor 6 provided in a part of the casing 4 and connected to a gear 14 etc. via a coupling 5. The optimum motor 6 is one that can be automatically controlled quickly and accurately.
It is desirable to use a pulse motor that can accurately maintain the controlled and changed position of the valve spool 31, which will be described later. Normally, the pulse motor does not move even if you try to move it, but when a signal is received to turn off the power and move it,
For the first time, it rotates by an amount corresponding to the number of commanded pulses, and when there is no rotation command, a force is acting to maintain the current position, and when there is a rotation command, the amount of rotation is controlled accurately at high speed. do. Of course, by doing so, not only can the opening degree of the valve spool 31 be adjusted arbitrarily, but also opening and closing can be performed each time.

The coupling ring 5 includes a cylindrical body 9 attached to the rotating shaft 7 of the motor 6, a catch 10 on the driven side, and a pin 1 attached by fitting both ends into the cylindrical body 9 and the catch 10, respectively.
1. The coupling ring 5 is made small, has a small inertia with respect to the transmitted torque, does not require much installation space, and is suitable for quickly and reliably performing opening/closing control and flow rate control in a valve device.

The catch 10 which is the driven side of the coupling ring 5 is
The gear 14 is connected to the shaft 13 supported by a bearing 13a.
is connected to. The gear 14 meshes with a gear 18, and the gear 18 is parallel to the shaft 13 in the center of the casing 4 via bearings such as a thrust bearing 15, a ball bearing 15a, a tapered roller bearing 15b, a shaft holding member 16, etc. The rotation of the motor 6 is transmitted to the shaft 17 via these gears 14 and 18. Note that the motor 6 and the shaft 17 may be disposed on the same axis, and the motor 6 and the shaft 17 may be connected via the coupling ring 5 without using the gears 14 and 18.

A nut 19 is screwed onto the outer periphery of the shaft 17 on the valve spool 31 side via a ball screw portion 17a. The nut 19 has a key 20, which is a type of rotation prevention member, in a part thereof, and the key 20 is attached to the casing 4.
The nut 19 is slidably fitted into a key groove 21 formed on the side, and the nut 19 on which the shaft 17 rotates can freely move forward and backward in the axial direction. Axis 17
The threaded connection between the nut 19 and the nut 19 may be an ordinary screw as long as the nut 19 guided by the key 20 is moved in the axial direction by the rotation of the shaft 17, but in order to operate efficiently, It is more ideal to use a ball screw with good transmission efficiency. In addition. In a ball screw that uses a ball screw, if a force in the axial direction is applied to the nut 19, the shaft 17 tries to turn, but in this case, since the rotation of the shaft 17 is blocked by the pulse motor 6, the shaft 17 doesn't turn.

A permanent magnet 22 is fixed to a part of the key 20 attached to the nut 19, and a magnetic position detector 23 called a zero cross sensor is mounted on a part of the casing 4 facing the permanent magnet 22. installed. The position detector 23 is composed of a proximity switch that is sensitive to the movement of the permanent magnet 22, and can accurately detect the movement distance of the nut 19 and the valve spool 31 in the axial direction, and provide feedback to the control device. ing.

When the valve is closed, if a method is adopted in which the outer periphery of the tip of the valve spool 31 is brought into contact with a stepped portion provided on the manifold 29 and mechanically stopped, the tip of the valve spool will get wedged in the stepped portion, and the next step will occur. Since a large force is required to start retracting the valve spool, in this embodiment, even when the valve is closed, the tip of the valve spool 31 is kept free without contacting the manifold 29. The valve is closed only by the outer peripheral surface of the valve spool 31. Therefore, the position detector 23 electrically detects the 0 position where the valve is fully closed, and the motor 6 is stopped based on that signal. The position detector 23 using magnetic action can detect with an accuracy of 0.01 mm.

Further, the nut 19 can maintain its horizontal center by slidably contacting the lower surface of the key 20 with the upper surface of the pedestal 24 that is attached to the casing 4 so as to be able to move up and down. It's summery. The pedestal 24 is supported by a cover 4b attached to the casing 4 via a spring 25 whose elastic force is calculated in advance and placed, and is configured to support the entire shaft 17 in a well-balanced manner. has been done.

This configuration was adopted in order to keep the shaft 17 horizontal and centered in order to smoothly operate the device without applying a lateral load to the ball bearing 15a. This is also to eliminate the difficulty and time it takes to center and set the image. Then, without applying loads such as those attached around the shaft 17,
This is because the entire load is received by the pedestal 24 and pushed up by the spring 25 to eliminate the load due to its own weight, eliminate deflection, and absorb changes in the center of gravity due to movement of the nut 19, etc. . Of course, the strength of the spring 25 can also be adjusted.

Further, a cylindrical portion 27 larger than the outer diameter of the nut 19 is integrally attached to the nut 19.
A valve shaft 28 is integrally provided at the tip of the cylindrical portion 27 . The center axis of the valve stem 28 is aligned with the axis 17. 26 is a space part. As shown in FIG. 2, in the cylindrical portion 27 surrounding the space 26, a plurality of through holes 27a are formed at predetermined pitches in a staggered manner in the circumferential direction. Hollow cylindrical part 2
7, and a plurality of staggered holes 27a are provided in this part.
The reason for this is that the force transmitted through the valve stem 28 escapes along the hole 27a as shown by the arrow in FIG. . The cylindrical portion 27 may be made thinner to increase the stress, but if such a hole 27
When a is present, an even better cushioning effect is exhibited.
Then, impact to the ball screw portion 17a is avoided.

Casing 4 housing shaft 17 and nut 19
The root portion is attached to the valve casing or manifold 29 forming the valve body by bolts (not shown). The manifold 29 has an inlet 29b at one end in the axial direction, seals the other end in the axial direction, and has annular circulation holes 33, 34 forming part of the outlet in the direction perpendicular to the axial direction.
In the valve chamber 30 communicating with the valve spool 31
The valve spool 31 is fitted to the valve shaft 28 so as to be slidable in the axial direction with extremely high precision.

As shown in FIGS. 1 and 3, the valve spool 31 is provided with a large number of through holes 31a and 31b extending in the axial direction. As can be seen from FIG. 1, the through holes 31a and 31b are also provided in a portion close to the outer peripheral surface of the valve spool 31, and the valve shaft 28 is provided at the axial center of the valve spool 31.
A part of the through hole 31 is provided through the through hole 31.
a and 31b are not provided at the axial center. The first
A first chamber 30a, which is an oil inflow chamber shown on the left side in the figure, and a second chamber 30b on the opposite side of the casing 4 have a large number of through holes 31a, which are formed through the valve spool 31. 31b. The second chamber 30b, which is the other end of the valve chamber 30 in the axial direction, has a sealed structure that is isolated from the outside of the valve chamber except for the through holes 31a and 31b.

This is done by making the axial pressing force of the hydraulic oil acting on the valve shaft 28 and nut 19 through the valve spool 31 relatively small, and by reducing the weight of the valve spool 31 itself. This is to allow the pulse motor 6 to rotate the shaft 17 easily. Along with the action of annular flow holes 33 and 34 forming part of the outlet 29c provided in a direction perpendicular to the axial direction of the valve chamber 30, which will be described later,
This is to enable the valve spool 31 to open as quickly and smoothly as possible by effectively utilizing the thrust force acting on the valve spool 31. Further, when the valve spool 31 opens to a predetermined large opening degree and tries to stop, the force acting in the direction of closing the valve spool 31 becomes an appropriate magnitude, and the valve spool 31 quickly stops and the valve spool 31 closes. This is to prevent the force required to hold the opening state from becoming too large.

Now, the hydraulic pressure acting on the first chamber 30a is PKg/cm ² ,
Assuming that the valve spool 31 does not have through holes 31a and 31b, the cross-sectional area of the valve spool 31 is Acm ² ,
If the cross-sectional area of the valve stem 28 is a cm ² , then the valve spool 3
If there are no through holes 31a, 31b in P.
A force of AKg acts on the valve stem 28, but if the valve spool 31 has the through holes 31a and 31b as described above, only a force of P·aKg acts on the valve stem 28. However, when the valve spool 31 moves to the right in FIG. 1, the oil in the second chamber 30b flows toward the first chamber 30a through the through holes 31a and 31b, The oil pressure in the first chamber 30b is higher than the oil pressure P in the first chamber 30a by ΔP, albeit momentarily. Therefore, at that time, the force acting on the valve stem 28 is A・P−(A−a)・ΔP
It has also become slightly smaller, making it possible to soften the impact. Note that if the valve spool 31 is provided with the through holes 31a and 31b, the valve spool 31 can be closed with a relatively small force not only when opening but also when closing.

A through hole 31 provided near the outer circumferential surface of the valve spool 31 is provided on the outer circumferential surface of the central portion of the valve spool 31.
An annular groove 32 is formed in communication with a and 31b.

Further, on the manifold 29 side, a constriction portion 29a is provided.
By providing this, the annular hydraulic oil circulation holes 33 and 34, which communicate with the outlet 29c provided in the manifold 29 on the secondary side, that is, the injection cylinder 41a side, and which constitute a part of the outlet, are aligned with the axis. It is formed perpendicular to the direction of the valve spool 3.
1 according to the movement of the groove 32 and the valve spool 3.
The state of communication with the tip of the valve 1 changes, making it possible to change the valve opening state and the flow rate.

In this case, the flow holes 33 and 34 are formed as annular grooves at the outlet portion of the inner peripheral surface of the manifold 29, as can be seen from FIG. here,
The reason why the circulation holes 33 and 34, which are also annular grooves, are provided is that when the oil flows out from the first chamber 30a etc. to the circulation holes 33 and 34, the valve spool 31 is connected to the first chamber 30a side by the action of the oil flow. The pressure acting on the surface of the through holes 31a, 3 near the outer peripheral surface, that is, the pressure acting on the surface of the through holes 31a, 3
This is also to take advantage of the fact that it becomes smaller at the 1b position.

In the middle of the valve spool 31, there is a first chamber which is an oil inflow chamber.
The reason for providing an annular groove 32 communicating with the chamber 30a and providing annular circulation holes 33 and 34 in the manifold 29 is to allow more oil to pass through with a small opening of the valve spool 31. That is, in the state shown in FIG. 1, oil not only flows from the first chamber 30a through the tip of the valve spool 31 to the circulation hole 33, but also flows from the through holes 31a, 31b and the groove 32 to the notch 32a. This is because the oil in the first chamber 30a is made to flow through the first chamber 30a to the circulation hole 34 as well.
Of course, two or more grooves 32 may be provided, and corresponding communication holes 34 may also be provided at two or more locations.
In this way, the diameter of the valve spool 31 can be reduced, and the entire valve device can also be made smaller.
Note that if the opening degrees of the flow holes 33 and 34 are b and c, respectively, when the valve spool 31 is opened to the maximum, b = c, so that the amount of oil flowing from both gaps is the same. is also good, and also c>b
When performing low-speed injection with a small opening, the flow hole 33 is blocked and oil flows only from the groove 32 to the flow hole 34. When the opening is large and high-speed injection is performed, the flow hole 33 is blocked. Oil may be allowed to flow from both 33 and 34.

A shaft sealing member 37 having a drain discharge function is provided between the casing 4 around the valve shaft 28 and the second chamber 30b on the valve chamber 30 side.

The portion of the manifold 29 that contacts the valve spool 31 may have a structure as shown in FIG. 4. In FIG. 4, the manifold 29 has a double structure, and a sleeve 40 with which the valve spool 31 is in direct contact is fitted inside. This sleeve 40 is formed with through holes 40a and 40b that communicate with the aforementioned communication holes 33 and 34, respectively. The machining accuracy between the inner circumferential surface of the sleeve 40 and the valve spool 31 is set to be relatively strict, so that even when large hydraulic pressure is applied, hydraulic oil may leak from the gap between the sleeve 40 and the valve spool 31, causing the flow hole 33, This was done to prevent it from flowing to the 34th side.

Instead, the machining between the outer peripheral surface of the sleeve 40 and the inner peripheral surface of the manifold 29 is made relatively rough;
A gasket 41 such as an O-ring prevents oil from leaking between the manifold 29 and the manifold 29. If such a structure is adopted, it is only necessary to increase the machining accuracy of only the inner circumferential surface of the sleeve 40, making the machining operation easy and extremely economical. That is, when the valve spool 31 is directly slidably assembled into the manifold 29, it is necessary to machine a highly precise hole in the manifold 29, which is difficult and time-consuming. 31, the holes in the manifold 29, which are difficult to machine, can be machined several times more roughly, and the inner peripheral surface of the sleeve 40, which is easier to machine, can be machined more severely. In addition, by providing the sleeve 40,
Even a slight misalignment can be sufficiently absorbed, the center can be maintained accurately to match the movement of the valve spool 31, and unreasonable force can be prevented from acting on the valve spool 31, etc. It can also be done.

Next, the operation of this embodiment configured as above will be explained.

First, when a die-casting machine or the like to which this flow rate regulating valve 1 is applied is in a non-operating state, the valve spool 31 is advanced leftward in FIG.
The communication between the first chamber 30a and the groove 32 of the valve spool 31 is blocked.

In this state, when a command to start low-speed injection is issued and a low-speed injection speed is commanded, the command is applied to the pulse motor 6, and the pulse motor 6 is rotated by a predetermined angle. Axis 17
Rotation is transmitted to. Rotation of shaft 17 is done by nut 19
It is transmitted to the nut 19 via the ball screw section 17 provided between the two, and the nut 19 retreats. The nut 19 is retracted from the valve spool 3 via the valve shaft 28.
For example, first, the groove 32 is brought into communication with the communication hole 34. Then, the primary side hydraulic oil guided to the first chamber 30a side on the tip side of the valve spool 31 is transferred to the through holes 31a, 31b and the groove 3.
2 into the flow hole 34, and is supplied to the head side of the injection cylinder 35, where low-speed injection is started. At this time, the degree of communication between the groove 32 and the communication hole 34, that is, the flow rate of the hydraulic oil, is accurately set in accordance with the injection cylinder 35 of the die-casting machine.

By the way, the valve spool 31 has through holes 31a, 3
Since the valve spool 31 has a lotus root-like structure in which the front and back are connected through the valve 1b, when the valve spool 31 is in the non-operating state, the pressure in the first chamber 30a on the tip side and the second chamber 30b on the retreating side is However, when the valve spool 31 retreats, the hydraulic oil on the second chamber 30b side is pushed back, and the through holes 31a, 31 on the first chamber 30a side are pushed back.
Although the pressure at position b is slightly smaller than the pressure on the second chamber 30b side, since oil pressure is applied to the tip side of the valve spool 31, the nut 19 is pushed through the valve spool 31, and the ball screw portion 17a The nut 19, which is screwed together through the screws, is constantly pressed rearward.

Therefore, the backlash that is inherent in any screwed state is eliminated, and highly accurate flow rate adjustment becomes possible.

In this way, the low-speed injection state is set and maintained for a predetermined time, but when a high-speed injection command comes, the pulse motor 6
, the shaft 17 is rotated and the nut 19 is further retracted. Nut 1 via ball screw part 17a
Since the retraction of valve 9 is extremely smooth and at a high speed, the valve spool 31 also retracts at a high speed.

When the valve spool 31 retreats to a predetermined position,
The communication area between the groove 32 and the communication hole 34 is further increased, and the first chamber 3 on the distal end side of the valve spool 31
Since the communication area between Oa and the communication hole 33 expands at once, a large amount of hydraulic oil is sent to the injection cylinder 41a via the communication holes 33 and 34, and high-speed injection starts almost instantaneously. When the high-speed injection is finished, the pulse motor 6 is operated again to close the valve spool 31.

In this device, two or more annular circulation holes 33, 34 are provided at the outlet, and the first chamber 30a and the second chamber 30b are connected by through holes 31a, 31b.
Through holes 31a, 31 are provided on the outer peripheral surface of the valve spool 31.
An annular groove 32 communicating with the valve spool 3 is provided.
Since the valve shaft 28 is provided only on the side opposite to the inlet 29b of the valve spool 31, and the area of the left side of the valve spool 31 is larger than the area of the right side, the force F ₁ in the direction of opening the valve spool 31 becomes large to some extent. When starting to move from low speed range to high speed range, valve spool 3
A force F ₁ in the direction of opening the valve spool 31 acts on 1,
This will help accelerate the opening of the valve, making it easier for the valve spool 31 to open quickly. This is 0.1~0.2m/sec
It is effective when it is necessary to change from a low speed of 1 to 5 m/sec in an extremely short time such as 0.05 seconds.

On the other hand, when the valve spool 31 retreats to a high speed range and the valve spool 31 is about to stop, the second chamber 30b is sealed from the outside except through the through holes 31a and 31b, and the valve spool 31 is closed. Since the opening degree is large and a large amount of oil flows from the first chamber 30a and the groove 32 to the circulation holes 33 and 34, a large suction action is generated, so the force _F2 in the direction of closing the valve spool 31 is applied to the valve spool. Acts on 31.
Therefore, since F ₂ acts as a brake on the valve spool 31, when the valve spool 31 stops at a predetermined high-speed opening position, it stops quickly and smoothly. This also helps shorten the valve opening time.

However, if this force F ₂ is too large, the brake is applied and is effective when stopping the valve spool 31, but if it becomes larger than necessary, the valve spool 3
A large force is required to hold the valve 1 after it has stopped at a high speed, and the holding mechanism for this purpose becomes large, which causes problems, especially when the valve has a large capacity such as 50 to 15,000/min. Therefore, this force
In order to make F ₂ an appropriate size, in the present invention,
Through holes 31a, 31b and grooves 32 are provided in the valve spool 31.
has been established. In this case, the through holes 31a and 31b are
As can be seen from FIGS. 1 and 3, it was also provided near the outer peripheral surface of the valve spool 31.

If this is done, an annular circulation hole 3 will be provided at the outlet.
3 and 34, when oil directly flows out from the first chamber 30a to the annular circulation hole 33,
Oil flows from the chamber 30a to the annular circulation hole 34 through the through hole 3.
1a, 31b and the groove 32, the first oil of the valve spool 31
The pressure acting on the surface on the chamber 30a side is the pressure applied to the valve spool 3
1, that is, the through holes 31a and 31b
At a certain position, the pressure becomes smaller than the pressure at the axial center of the valve spool 31.

On the other hand, since there are these through holes 31a and 31b,
The through hole 31 in the surface of the valve spool 31 on the first chamber 30a side is formed on the surface of the valve spool 31 on the second chamber 30b side.
This means that the same pressure as the pressure acting on positions a and 31b is acting on the valve spool 3.
1 is relaxed, and the force acting on the valve spool 31 is reduced by the force acting on the through holes 31a, 3.
If the position of 1b is appropriately designed in advance,
It can be set to a desired size.

For reference, in the present invention, instead of providing the through holes 31a and 31b in the valve spool 31, a passage provided inside or outside the manifold 29 connects the inner circumferential surface of the first chamber 30a and the second chamber. Room 30
If the inner surfaces of b are connected, when the valve spool 31 opens to a high speed range, the relatively high pressure in the first chamber 30a acts directly on the second chamber 30b, and acts in the valve closing direction. The force F ₂ will be much larger than necessary. This means that when stopping the valve spool 31, which continues to open, in a high-speed range, the brake is applied more forcefully, which is effective, but in order to hold the valve spool 31 in a stopped state in a high-speed range, an unnecessarily large force is required. Therefore, the holding mechanism becomes large, especially when the valve is 50 to 15,000/
If you increase the capacity like min, it will cause problems.

Therefore, as described above, in order to make the force _F2 in the valve closing direction acting on the valve spool 31 in the high speed range relatively small and to have an appropriate value,
In the present invention, the through hole 31a in the valve spool 31,
31b was provided.

In this embodiment, the force acting on the valve spool 31 appeared as shown by the solid line in FIG.

In FIG. 5, the flow rate Q (the flow rate or the opening degree of the valve spool 31 may be used) is plotted on the axis, and the force acting on the valve spool 31 is plotted on the vertical axis. F ₁ indicates a force in the direction of opening the valve spool 31, and F ₂ indicates a force in the direction of closing the valve spool 31.

As can be seen from FIG. 5, in the spool valve of the present invention, when the valve spool 31 begins to move from the low speed range to the high speed range, the force F ₁ acting in the direction in which the valve spool 31 opens is large. The valve spool 31 therefore begins to open quickly with relatively little force.
Then, when the valve spool 31 finishes moving from the low speed range to the high speed range and the valve spool 31 is about to stop, a force acts in the direction in which the valve spool 31 closes.
_F2 is large. Therefore, when the speed shifts to high speed and the valve spool 31 is about to stop, the brake is increased accordingly, and the valve spool 31 stops quickly. By these things, the time required for the valve spool 31 to start and stop can be shortened accordingly. This is extremely effective in the injection operation of a die-casting machine, where the time required to change from low speed to high speed is extremely short, for example, 0.05 seconds.

Furthermore, as can be seen from FIG. 5, the holding force of the valve spool 31 in the high speed range is approximately the same as the holding force of the valve spool 31 in the low speed range.
This allows the holding force to be set to an appropriate level.

By the way, as a comparative example, as mentioned above, the seventh
When FIG. 8, which shows the relationship between the flow rate and the force acting on the valve body in the conventional example shown in the figure, is superimposed on FIG. 5, it becomes as shown by a chain line. In the conventional one shown by the dashed line, the left and right spools 72a,
72b are connected by a shaft 72c, and the areas on which hydraulic pressure acts on the left and right spools 72a and 72b are the same, so no force in the valve opening direction acts on the valve body 72. When the valve opening degree is small and the flow rate Q is small, a force F ₂ acts on the valve body 72 in the valve closing direction.
is relatively small, and when the valve opening degree is large and the flow rate Q becomes large, the force F ₂ acting on the valve body 72 in the valve closing direction becomes considerably large. Therefore,
In the conventional example, in the valve opening operation start region, the force in the valve opening direction is
F ₁ does not act; rather, the force in the valve closing direction is applied from the beginning.
Since _F2 acts as a braking force, the valve opening speed becomes slower. Furthermore, when the valve opening reaches a predetermined amount and the valve body 72 is stopped, the force _F2 in the valve closing direction becomes large, so this becomes a braking force to stop the valve body 72. Although it works effectively,
A considerably large force is required to hold the valve body in order to keep the valve open.

In this way, as can be seen from the comparison with the conventional example, in this device, the thrust force can be effectively applied to the valve spool 31, and the action of the valve spool 31 can be performed more quickly and smoothly, and can be stabilized. I can,
Extremely good effects can be obtained.

[Effects of the Invention] As is clear from the above description, in the present invention, as described in the claims, the valve spool 31 is provided slidably within the manifold 29.
Through holes 31a and 31b are provided in the valve spool 31, and the valve spool 31
A groove 32 communicating with the first chamber 30a, which is an oil inflow chamber on the tip side, is provided to connect the first chamber 30a and the manifold 2.
Annular circulation hole 3 which is an oil outflow hole provided in 9
3 and 34 are provided at two or more locations in the axial direction of the valve spool 31, so when the valve spool 31 is moved, oil flows through the two or more throttle locations at the same time. Therefore, if the moving distance of the valve spool 31 is the same, the diameter of the valve spool 31 can be reduced to less than half. That is, even if the diameter of the valve spool 31 is made small, a large flow rate can be freely adjusted.

As a result, the moving part of the valve can be made light and the inertia can be reduced, and the valve spool 31
By providing through holes 31a and 31b in the valve shaft 28, the force acting on the valve shaft 28 can be reduced, so that the valve can be opened and closed quickly and smoothly.

Furthermore, since the entire valve can be made smaller, less space is required for installation.

Of course, if the diameter of the valve spool 31 is kept the same as the conventional one, if the valve spool 31 is moved by the same distance as the conventional one, a large amount of oil can pass through at once, so a large flow rate can be adjusted. can be carried out freely.

In addition, in the present invention, one flow regulating valve 1
Therefore, if the four valves, the flow rate adjustment valve and on-off valve for low-speed injection and the flow rate adjustment valve and on-off valve for high-speed injection, serve as the same, there is no need to provide multiple valves of each type as in the past, and injection The overall structure of the device is extremely simple and compact, and the hydraulic piping can be shortened, which is extremely advantageous economically.

Further, since the speed can be adjusted virtually steplessly with one flow rate regulating valve 1, the structure becomes simpler as compared to conventional devices, the more speed steps there are in one cycle.

Furthermore, in the present invention, annular circulation holes 33 and 34 are provided at two or more outlet portions, and the valve spool 3
Through holes 31a and 31b are provided in the valve spool 3.
An annular groove 32 communicating with the first oil chamber 31a through through holes 31a and 31b is provided in the middle of the outer peripheral surface of the valve spool 31, and a valve shaft 28 is provided only on the side opposite to the inlet 29b of the valve spool 31. Therefore, when the valve spool 31 starts to shift from a low speed range with a small opening to a high speed range with a large opening, apply a force in the opening direction to the valve spool 31 so that the valve spool 31 moves to a high speed range and stops. When doing so, the valve spool 31
In addition, the holding force of the valve spool 31 can be set to an appropriate force in the low speed range and high speed range, and the opening operation of the valve spool 31 can be performed quickly and smoothly with a relatively small force. can be done. This becomes extremely useful when, for example, a die-casting machine changes greatly from a low speed of 0.1 to 0.2 m/sec to a high speed of 1 to 5 m/sec in an extremely short period of time, such as 0.05 seconds. .

Note that if a pulse motor is used as the motor 6 and the rotation amount of the motor is controlled by inputting desired pulses to the pulse motor, the opening/closing operation and opening degree adjustment of the flow rate regulating valve 1 can be accurately performed. It can be done quickly and automatically.

Since the screw mechanism 17, 17a, 19 that changes the rotation of the motor 6 to change the stroke of the valve spool 31 is used to adjust the flow rate, the movement of the valve spool 31 is automatically performed at extremely high speed and accurately. It is possible to switch from low-speed injection to high-speed injection with good responsiveness, accurately, and at high speed, and high-speed injection can be reliably controlled. Of course, the valve spool 31 is also connected to the motor 6.
The valve spool 31 has an integral structure with the nut 19, which is moved forward and backward by the rotation of the valve spool 31. Since hydraulic pressure is always applied to the valve spool 31 in a fixed direction, the relationship between the nut 19 and the threaded shaft 17 to which it is screwed is fixed. This eliminates the gap between the two, allowing accurate flow rate control.

When the valve is opened to the desired opening degree, disturbances caused by pressure fluctuations in the hydraulic circuit or hydraulic shock caused by switching of other valves will cause the valve spool to
Even if an attempt is made to move the valve spool 31 in the axial direction by acting on the nut 19
Since the motor 6 is connected via the screw shaft 17, the valve spool 31 is completely unaffected by external disturbances, and the valve spool 31 does not move at all in the axial direction except by the operation of the motor 6. Therefore, the flow rate is very stable and the injection speed can be kept constant, so if you use this device to inject molten metal,
Injection can be performed in good conditions, and high-quality injection products can be reliably and easily obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a cylindrical portion 2 between the nut and the valve shaft in FIG. 1.
7 is a plan view, and FIG. 3 is a cross-sectional view taken along the - line in FIG. 1.
Fig. 4 is a sectional view showing another embodiment of the manifold portion, Fig. 5 is a diagram showing the relationship between the flow rate and the force acting on the valve spool in this embodiment and the conventional example shown in Fig. 7; 6 and 7 are hydraulic circuit diagrams and longitudinal sectional views showing different conventional examples similar to the present invention, and FIG. 8 shows the flow rate and force acting on the valve body in the conventional example shown in FIG. 7. It is a line diagram showing a relationship. DESCRIPTION OF SYMBOLS 1... Flow rate adjustment valve, 2... Drive unit, 3... Flow rate adjustment unit, 4... Casing, 6... Pulse motor, 17... Shaft, 17a... Ball screw part, 19
... Nut, 23 ... Position detector, 27 ... Cylindrical part, 28 ... Valve stem, 29 ... Manifold, 29
b...Inlet, 29c...Outlet, 30...Valve chamber, 3
0a...First chamber, 30b...Second chamber, 31...Valve spool, 31a, 31b...Through hole, 32...
Groove, 33, 34...Outflow hole, 35...Injection cylinder, 40...Sleeve.

Claims (1)

[Claims] 1 Place the valve spool 31 into the valve chamber 3 of the manifold 29.
0, an inlet 29b is provided at one end in the axial direction of the valve chamber 30, and a part of the outlet is formed in a direction perpendicular to the axis of the valve chamber 30. Two or more annular circulation holes 3
3 and 34 are provided, and these flow holes 33 and 34 are provided so as to merge with one outlet 29c, and a valve spool 31 is provided in the valve chamber 30 so as to be slidable in the axial direction, so that the flow occurs on the outer peripheral surface of the valve spool 31. The holes 33 and 34 are provided so that they can be opened and closed, and the valve spool 31 separates the valve chamber 30 into a first chamber 30a with an inlet 29b and an inlet 2.
The valve shaft 28 is divided into a second chamber 30b on the opposite side to the side where the valve spool 9b is located, and a valve shaft 28 extending to the outside of the second chamber 30b is provided at the shaft center of the second chamber 30b side of the valve spool 31. The tip portion is connected to the motor 6 via screw mechanisms 17, 17a, 19 that change rotational motion into axial motion, and a large number of through holes 31a, 31b are provided inside the valve spool 31 that penetrate in the axial direction. The second chamber 30b and the first chamber 30a, which are cut off from the outside except for the through holes 31a and 31b, are made to communicate with each other, and through holes 31a and 31b are provided on the outer peripheral surface part of the valve spool 31 in the axial direction. An annular groove 32 is provided that communicates with the middle of the first chamber 30a.
A hydraulic circuit for a hydraulic circuit in which two or more locations in the axial direction of the valve spool 31 are provided with locations for communicating and blocking the annular circulation holes 33 and 34 directly and indirectly through the through holes 31a and 31b and the annular groove 32. Flow rate adjustment valve.