JPH0942203A - Nozzle flapper type electromagnetic proportional servo valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle flapper type electromagnetic proportional servo in which the disassembling of a spool valve portion is easy and the maintenance by an end user is facilitated. SOLUTION: One pair of elastic bodies 13, 14 arranged in the cylinder spaces of both ends of a spool 9 are used as a balance means of the spool 9. While the fluctuation of a nozzle flapper 4 is suppressed by jet pressures from nozzles 5, 6 so that nozzle back pressure difference is adjusted so as to be constant in a range of a predetermined supply pressure. Thereby, a conventional feedback spring for connecting spool; and a nozzle flapper and feeding back a spool displacement to a nozzle flapper is abolished, a nozzle flapper valve portion 15 and a spool valve portion 16 become separable, and the disassembling of the spool valve portion 16 becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle flapper type electromagnetic proportional servo valve used in a servo control system.

[0002]

2. Description of the Related Art A servo valve is for adjusting a valve opening degree arbitrarily by a feedback signal from the control section in a servo loop for driving or positioning control of a controlled section using pneumatic pressure or hydraulic pressure. Are widely used as control valves for various machine tools and other industrial machines, especially in recent years, robots used for various purposes.

FIG. 2 is a plan view showing a sectional structure of a nozzle flapper type electromagnetic proportional servo valve, which is one type of conventional servo valve.

The torque motor 51 includes an armature 52 and a coil 5.
And 3. The armature 52 receives the input control signal and is tilted by the magnetic field generated by the coil 53. Then armature 5
Nozzle flapper 54 connected to 2 swings,
Nozzle back pressures Pn1 and Pn2 of 5, 56 are generated. The spool 59 is displaced in the cylinder due to this nozzle back pressure difference. This displacement is fed back to the nozzle flapper 54 by the feedback spring 60 connected to the spool 59. With this feedback, the nozzle flapper 5
4 returns to the central position and Pn1 = Pn2, that is, at a position where the nozzle back pressure difference becomes 0, the spool 59 equilibrates and stops. In the figure, for example, when the spool 59 is displaced to the right, the control ports P1 and P provided on the cylinder wall
The second window opens according to the displacement, and the hydraulic oil is connected to the control pressure P from the pressure port Ps connected to the supply pressure source.
The hydraulic oil supplied to the controlled system via 1 and discharged from the controlled system is sucked into the return port Pr via the control port P2. As described above, since the input control signal to the torque motor 51 controls the opening degree of the window of the cylinder wall, the driving force supplied to the controlled system is also controlled by the input control signal.

In this nozzle flapper type electromagnetic proportional servo valve, a part of the hydraulic oil flowing from the supply pressure source is flowed to the orifices 57 and 58 and the nozzles 55 and 56 having a small flow passage cross-sectional area, and the nozzle back pressure generated here is generated. Is controlled by changing a minute gap between the nozzles 55 and 56 and the nozzle flapper 54. The filter 61 is provided in order to remove dust from the working oil that flows into the minute flow passages such as the orifice, the nozzle, and the gap between the nozzle and the nozzle flapper, and to prevent clogging of these portions. The filter 61 has a cylindrical shape, and the orifices 57 and 58 are inserted into the openings at the ends of the filter 61 and attached to the main body of the nozzle flapper type electromagnetic proportional servo valve.

A nozzle flapper type electromagnetic proportional servo valve
Compared with an electromagnetic proportional valve that directly drives a spool valve with an electromagnet, it has the following features. First, the nozzle flapper amplifies the input to the previous stage to drive the spool valve, so the dynamic characteristics are about three times better, and the power consumption is 10 to 10 in the solenoid proportional valve.
Even if it requires 50 W, it can be driven by a few tenths thereof. In addition, the solenoid proportional valve has a spool driving force of 3 to 5k.
It is weak as gf, and has characteristics that are different when the port is opened and when it is closed due to the influence of the flow force, and there is a characteristic that it tries to return quickly when the port is closed, which makes it unsuitable for shockless control.

[0007]

Although the conventional nozzle flapper type solenoid proportional servo valve has many advantages as compared with the solenoid proportional valve as described above, the nozzle flapper 54 and the spool 5 are provided.
9 has a structure in which it is connected by a feedback spring 60, and since the nozzle and the nozzle flapper are processed with high precision, the end user disassembles this, and, for example, the spool 59 is taken out and washed, and again. There was a problem that it was difficult to reassemble.

Further, when replacing the filter 61, it is necessary to remove the orifices 57 and 58 from the filter 61. At this time, there is a problem that the holes of the orifices 57 and 58 come into contact with the filter 61 to easily cause dust clogging.

As described above, the conventional nozzle flapper type electromagnetic proportional servo valve has a problem in that the end user cannot easily perform maintenance.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzle flapper type electromagnetic proportional servo valve which facilitates disassembly of a spool valve portion and replacement of a filter so that an end user can easily perform maintenance.

[0011]

In the nozzle flapper type electromagnetic proportional servo valve according to claim 1 of the present invention, the balance means of the spool is a pair of elastic bodies arranged in the cylinder space at both ends of the spool, and the torque motor. An input signal range adjusted so that the nozzle back pressure difference is constant within a predetermined supply pressure range by utilizing the phenomenon that the nozzle flapper swung by the nozzle receives a jet pressure of a strength corresponding to the swing amount and is pushed back. It is characterized by having.

Since the present invention has no feedback spring, the nozzle flapper is not located at the midpoint between the two nozzles when the spool moves to the equilibrium point. That is, the nozzle back pressure difference does not become zero when the spool is balanced. Therefore, even if the input signals are the same, if the supply pressure is different, the nozzle back pressure difference is different, and the spool displacement amount is also different. This means that the driving force for the controlled system changes depending on the supply pressure source, which is inconvenient when using the servo valve. Therefore, in the present invention, while the nozzle flapper is oscillated by receiving a force from the torque motor, the ejection pressure of the intensity corresponding to the oscillating amount is received from the nozzle and pushed back, so that the nozzle back pressure difference in the used input signal range is increased. Is adjusted to be constant within a predetermined supply pressure range. Specifically, this is achieved by adjusting the balance between the ejection pressure difference from both nozzles and the torque of the torque motor or the elastic force of the nozzle flapper.

According to the present invention, the feedback spring for connecting the nozzle flapper and the spool is eliminated by the above means, and the spool is balanced by the pair of elastic bodies arranged in the cylinder spaces at both ends of the spool. Therefore, the nozzle flapper valve portion and the spool valve The part and the part can be configured to be separable.
As a result, the spool valve portion can be easily disassembled and the end user can easily perform the maintenance.

A nozzle flapper type electromagnetic proportional servo valve according to a second aspect of the present invention is a filter provided at a position where it cannot contact an orifice, and removes contaminants from a fluid supplied from a supply pressure source to a nozzle. It is characterized by having a fluid cleaning filter.

According to the present invention, when the fluid cleaning filter is replaced by the above means, the fluid cleaning filter contaminated with dust does not come into contact with the orifice. As a result, the filter can be easily replaced, and the end user can easily perform the maintenance.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A nozzle flapper type electromagnetic proportional servo valve, which is an embodiment of the present invention, will be described below.

FIG. 1 is a plan view showing a sectional structure of a nozzle flapper type electromagnetic proportional servo valve embodying the present invention.
The torque motor 1 has an armature 2 and a coil 3. The coil 3 generates a magnetic field according to the input control signal and exerts a torque on the armature 2. That is, the armature 2 tilts clockwise or counterclockwise with respect to the axis perpendicular to the drawing according to the magnetic field of the coil 3. A nozzle flapper 4 is connected to the armature 2, and the nozzle flapper 4 has a pair of opposing nozzles 5,
6 so as to face them. Nozzle 5,
6 is connected to a pressure port Ps which is a supply pressure source via orifices 7 and 8. Due to the fluid continuity condition, the velocity of the fluid flowing through the tube is inversely proportional to the cross-sectional area of the tube, thus increasing the velocity of the fluid throttled by the orifice. At the same time, the fluid pressure drops due to Bernoulli's theorem.

When the input control signal is 0, the armature 2 is not tilted, the nozzle flapper 4 is located at the center of the nozzles 5 and 6, and the nozzle back pressures Pn1 and Pn2 of the nozzles 5 and 6 are equal. One end 10 of the spool 9 is located between the nozzle 5 and the orifice 7, receives the nozzle back pressure Pn1 of the nozzle 5, and the other end 11 of the spool 9 similarly has the nozzle back pressure Pn of the nozzle 6.
Receive 2. However, since Pn1 = Pn2, the spool 9 is not displaced from the center position. Therefore, since the spool 9 is closed between the control ports P1 and P2 and the pressure port Ps and the return port Pr, the fluid does not flow and the output of the servo valve is 0.

Next, consider a case where the armature 2 is tilted clockwise in response to the input control signal. At this time, the nozzle flapper 4 swings to the left, the gap between the nozzle flapper 4 and the nozzle 5 becomes smaller, and conversely, the gap between the nozzle flapper 4 and the nozzle 6 becomes larger. Therefore, the nozzle back pressure of the nozzle 5 is higher than the nozzle back pressure of the nozzle 6, that is, Pn1> Pn2. Nozzle back pressure Pn1, Pn2
Respectively act on the spool ends 10, 11 and the spool 9
Is displaced to the right due to this nozzle back pressure difference. Coil springs 13 and 14 are provided as elastic bodies in the space between the side plate 12 that is the cylinder end surface and the spool ends 10 and 11, respectively. When the spool 9 is displaced to the right, the coil spring 1
Since 4 is compressed, the coil spring 14 receives a leftward force. The spool 9 is displaced to a position where the spring force and the nozzle back pressure difference are balanced. When the spool 9 is displaced, the windows of the control ports P1 and P2 on the cylinder wall are opened according to the displacement, and the hydraulic oil is supplied from the pressure port Ps connected to the supply pressure source to the controlled system via the control port P1. The hydraulic oil discharged from the controlled system is sucked into the return port Pr via the control port P2. Since the input control signal to the torque motor 1 controls the opening degree of the window of the cylinder wall, the driving force supplied to the controlled system is also controlled by the input control signal.

The general operation of the nozzle flapper type electromagnetic proportional servo valve according to this embodiment has been described above. continue,
The operation of the nozzle and the nozzle flapper will be described in detail.

Since the present nozzle flapper type electromagnetic proportional servo valve has no feedback spring, the nozzle flapper 4 is not located at the midpoint between the two nozzles even when the spool 9 moves to the equilibrium point. That is, the nozzle back pressure difference does not become zero when the spool is balanced. With this servo valve, for input signals in a predetermined range, the nozzle back pressure difference becomes constant even if the supply pressure to the pressure port Ps changes within the predetermined range.
The oscillating amount of the nozzle flapper 4 is suppressed by the ejection pressure from the nozzle that is proportional to the supply pressure. That is, the nozzle flapper 4 is swung by receiving a force from the torque motor 1, while the nozzles 5 and 6 receive a large difference in ejection output in a direction in which the swing is suppressed as the swing amount and the supply pressure increase. . As a result, the increase in the nozzle back pressure difference due to the increase in the supply pressure and the decrease in the nozzle back pressure difference due to the suppression of the swing amount of the nozzle flapper 4 are offset, and the nozzle back pressure difference does not fluctuate due to the fluctuation in the supply pressure.

The specific construction of this servo valve uses a motor that produces a torque of 0.4 kg.cm at a maximum of 20 mA as the torque motor 1, and the holes of the nozzles 5 and 6 are 1 mm.
In the neutral position of the nozzle flapper 4, the gap between the nozzle flapper 4 and the nozzles 5 and 6 is 80 μm. In the conventional nozzle flapper type electromagnetic proportional servo valve, for the same torque motor, the nozzle hole had a diameter of 0.4 mm, and the gap between the nozzle flapper and the nozzle was 50 μm at the neutral position. As can be seen from this, in this servo valve, the jet output of the nozzle is made stronger than in the conventional case as compared with the torque of the torque motor, and the swing of the nozzle flapper is suppressed in proportion to the supply pressure. This servo valve can be used for controlling the flow rate (supply pressure) range of 60 to 180 l / min.

With the above construction, the servo valve is constructed so that it can be separated into the nozzle flapper valve portion 15 and the spool valve portion 16. Unlike the conventional nozzle flapper type solenoid proportional servo valve, since the nozzle flapper valve portion 15 and the spool valve portion 16 are not connected by a feedback spring, the end user can easily separate the two portions.
Further, the side plate 12 of the spool valve portion 16 can be removed to take out the spool 9, and the flow passage, the cylinder and the spool 9 inside the spool valve portion 16 can be cleaned. It can also be easily reassembled after cleaning.

The plate-like filter 17 is a fluid cleaning filter, and is arranged in the nozzle flapper valve portion 15 at three places where fluid can flow into the nozzles 5 and 6 so as not to come into contact with the orifices 7 and 8. These plate filters 17
Removes contaminants from the fluid supplied to the nozzles 5, 6 from the supply pressure source. If dirt builds up, the nozzle flapper valve portion 15 and the spool valve portion 16 can be separated and removed from the nozzle flapper valve portion 15 for cleaning or replacement. At this time, since the plate filter 17 is not in contact with the orifices 7 and 8, dust accumulated in the plate filter 17 is unlikely to adhere to the orifices 7 and 8, and the end user can easily perform maintenance.

[0025]

The nozzle flapper type electromagnetic proportional servo valve of the present invention has an effect that the spool valve portion can be easily disassembled and the filter can be easily replaced, and the end user can easily perform maintenance.

[Brief description of drawings]

FIG. 1 is a plan view showing a sectional structure of a nozzle flapper type electromagnetic proportional servo valve according to an embodiment of the present invention.

FIG. 2 is a plan view showing a cross-sectional structure of a conventional nozzle flapper type electromagnetic proportional servo valve.

[Explanation of symbols]

1 torque motor, 2 armatures, 4 nozzle flapper,
5,6 nozzles, 7,8 orifices, 9 spools,
13, 14 Coil springs, 17 Plate filters.

Claims (2)

[Claims] 1. A pair of nozzles, which are connected to a supply pressure source through an orifice and are arranged so as to face each other, and a nozzle which is provided so as to face each nozzle and which is swung by a torque motor which receives an input signal. It has a nozzle flapper that generates a nozzle back pressure difference, a spool valve that causes the spool to reciprocate in the cylinder, and a spool balancing unit that exerts a restoring force on the spool in proportion to the displacement of the spool. Guided to different ends, the spool is displaced to the equilibrium point between the nozzle back pressure difference at both ends and the restoring force by the spool balancing means, and in the nozzle flapper type solenoid proportional servo valve that outputs a flow rate proportional to the displacement, the spool The equilibrium means is a pair of elastic bodies arranged in the cylinder space at both ends of the spool, and the nozzle flapper sways due to the jet pressure from the nozzle. A nozzle flapper valve portion including a nozzle, a nozzle flapper, an orifice, and a torque motor, and a spool valve portion including a spool valve, which has an input signal range that is suppressed and adjusted so that a nozzle back pressure difference is constant in a predetermined supply pressure range. Nozzle flapper type solenoid proportional servo valve characterized by being separable. 2. The nozzle flapper type electromagnetic proportional servo valve according to claim 1, wherein the filter is provided at a position where it cannot contact the orifice, and removes contaminants from the fluid supplied from the supply pressure source to the nozzle. A nozzle flapper type solenoid proportional servo valve characterized by having a fluid cleaning filter.