JPH02118204A - Dither generation method for pneumatic-hydraulic servo and device therefor - Google Patents

Abstract

PURPOSE:To enable usage of plant air and the like having no air pulsation by generating dither on a circuit from an air source to a spool by means of an air circuit including a periodic change mechanism of air circuit resistance which is rotated interlocking with a hydraulic pump shaft. CONSTITUTION:In a dither generation device, a chopper plate 4 is mounted on a driving shaft 50 of a driving motor 5, an oil supply pump 2 is connected thereto, and an air nozzle 3 having a connection part 30 with a plant air 9 as an air source is provided opposing to the plate 4. Air is supplied from the plant air 9 through a variable throttle 11 to the air nozzle 3 and a servo valve 10 by the operation of a driving motor 5. The air is then discharged from a discharge port 31, and a pulse 12 is given to the air. Frequency and amplitude of dither is changed by adjusting a distance between chopper plates, the shapes and the number thereof, and gaps between the chopper plates and the adjacent air nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates primarily to a dither generator for a servo valve operated by an air signal.

The servo valve needs to use a minute signal pressure to cause the spool to take a position corresponding to the signal pressure, and in order to eliminate the influence of static friction force, dither, that is, small pulsations are added to the signal pressure.

[Conventional technology]

Conventionally, most methods for dithering air-operated hydraulic servo valve systems have utilized pulsations in the discharge pressure of an air blower. For example, in the case of a vane-type blower, the dither capacity was determined by the number of blades.

[Problem to be solved by the invention]

Dither is added to the input signal of the hydraulic servo valve. That is, the spool of the servo valve needs to be held at a position corresponding to a minute signal, and small pulsations are always applied to it in order to remove the influence of static frictional force. However, in the conventional technology, it is essential to be equipped with an air blower to provide pulsation, and for example, when using non-pulsating factory air, etc., it was not possible to obtain dither. Furthermore, air blowers with a large number of blades such as sirocco fans, which are advantageous in terms of performance and processing, cannot be used because the air pulsation is small. Furthermore, it has been impossible to change the dither frequency and amplitude (number of pulsations, magnitude of pulsations) in accordance with the performance of the servo valve.

Therefore, the present invention was developed in view of these drawbacks, and it makes it possible to use factory air, etc. without air pulsation, and also makes it possible to use a high-performance blower with little pulsation.
Another object of the present invention is to provide a dither generator for an air-operated hydraulic servo valve that can easily and accurately change the dither frequency and amplitude.

[Means to solve problems]

A dither generation method for an air-hydraulic servo valve according to the present invention generates dither in the pressure of an air source supplied to a pneumatic signal generator and superimposes it on the pneumatic signal in a control system including a hydraulic servo valve operated by a pneumatic signal. When determining the position of the spool by applying a signal force to the spool and balancing it with the force of the spring, the air source is provided by an air circuit that includes a periodic variation mechanism of the air circuit resistance that rotates in conjunction with the hydraulic pump shaft of the hydraulic system. Dither is generated in the circuit from to the spool.

According to a preferred embodiment, the air resistance cycling mechanism is interposed in an air discharge circuit that communicates with the spool.

According to other embodiments, the air resistance cycling mechanism is interposed in a bypass circuit communicating with the spool.

The dither generator for an air-hydraulic servo valve according to the present invention rotates in conjunction with a oil supply pump for a hydraulic servo valve in a system in which the spool of a hydraulic servo valve is operated and controlled by air pressure, and is connected to a pipe line connected to an air supply source. Pulsation is applied to the air line by periodically changing the resistance using an air resistance periodic change mechanism.

According to another embodiment, the periodic change mechanism is constructed by using a chopper plate and attaching it to the drive shaft of the drive motor.

In other embodiments, the chopper plate is constructed by attaching to the rotor or coupling of an air blower.

[Effect]

The present invention independently connects a dither generation mechanism using the drive source of a hydraulic servo system (for example, an electric motor) and the rotation shaft of an oil pump (an air blower may be added). connects a chopper plate to a rotating shaft and provides air nozzles close to its circumference,
The air source consists of, for example, factory air (air from an air blower added to the system being implemented), and the hydraulic servo system is driven to rotate the rotary shaft, thereby rotating the chopper plate. This device generates dither by opening and closing adjacent air nozzles to pulsate the nozzle back pressure.The device generates dither by opening and closing adjacent air nozzles and pulsating the nozzle back pressure. The frequency and amplitude can be changed.

〔Example〕

An embodiment of the dither generator of the present invention will be described below with reference to the drawings.

(First Embodiment) As shown in FIG. 1, the dither generator according to the present invention has a chopper plate 4 attached to a drive shaft 50 of a drive motor 5, and a refueling pump 2 connected thereto. At least, it is configured by providing an air nozzle 3 having a connection part 30 with the factory air 9 as an air source, and by rotating the drive motor 5, the factory air 9 is connected to the air nozzle 3 through the variable throttle 11. It is configured to be able to give pulsation 12 to the air supplied to the servo valve 10. Note that 31 indicates an air outlet.

(Second Embodiment) FIG. 2 shows a second embodiment of the dither generator of the present invention. In particular, the first embodiment is replaced with factory air 9 in the device, and the air blower 1 is replaced by a drive motor 5. Chopper plate 4. This shows a case in which the air blower 1 is connected coaxially with a hydraulic motor 2, and air from the air blower 1 is supplied to an air nozzle 3 and a servo valve 10 via a variable throttle 11. Similarly to the device shown in FIG. 1, the chopper plate 4 is rotated to provide pulsation.

In addition, 1st. In the second embodiment, the chopper plate 4 was constructed by being attached to the rotating shaft 50 of the drive motor 5, but it may also be constructed by attaching the chopper plate 4 to the rotor or coupling of the air blower 1. is also possible.

FIG. 3 shows an example of a hydraulic servo valve system for controlling the state of a workpiece, for example, controlling the edge position of a running web, and particularly shows the configuration of a dither circuit section to which the dither generator of the present invention is applied. It is something that

Therefore, if the factory air 9 is used in the same circuit, the air blower 1 becomes unnecessary.

Also, the arrow 16 of the object to be measured 14 (for example, a running web)
When the displacement in the direction is detected by the air sensor 8, the detected air signal is input to the air pressure converter (diaphragm) 7. The displacement of the air pressure converter 7 controls the spool of the hydraulic servo valve 6, and by operating the hydraulic cylinder 13, the measurement object 14 is controlled in the direction of the arrow 16 and held at the set end position.

The dither circuit applies pulsations to the air pressure converting section 7 through the air nozzle 3 provided close to the chopper plate 4. Therefore, dither can be applied to the spool of the hydraulic servo valve 6 by the air pressure converter 7 at the rotation period of the chopper plate 4. Here, we have shown an example in which the output for the air pressure dither signal given to the pressure converter 7 is periodically changed by the chopper plate. Good too,
Reference numeral 15 indicates a throttle mechanism that allows a minute amount of air to flow for dust-proof purging.

FIG. 4 shows an example in which the dither signal generating resistor 4 having the second configuration is integrated with the blower 1.

The blower 1 supplies air pressure to an air pressure converter 7, e.g., the diaphragm shown in FIG. 3, and an air pressure sensor 8, e.g., the sensor shown in FIG. 3, through a throttle 11. As shown in FIG.
The pulsation generating member shown in the figure generates pulsations and releases them into the atmosphere. Other points are the same as in FIG.

FIG. 5 shows an example in which air is supplied from another air source 9.
Supply air pressure as shown in the figure. In this case, the bypass circuit 20 is branched from the air 110X9 and the air is supplied to the air pressure converter 7 via the dither generating resistor 4. Other points are the same as in FIG. In the case of FIG. 5 as well, by selecting the aperture 11, pulsations of the required strength can be added to the main air flow.

〔Effect of the invention〕

As is clear from the above explanation, according to the dither generator for an air-operated hydraulic servo valve of the present invention, it is possible to use factory air without air pulsation or an air blower, and there is no restriction on the air source. This makes it easy to provide optimal pulsation, which greatly expands the range of applications and greatly reduces the cost of the system.

[Brief explanation of drawings]

FIG. 1 is a partially longitudinal side view showing a first embodiment of the dither generator of the present invention, FIG. 2 is a partially longitudinal side view showing the second embodiment, and FIG. 3 is for controlling the edge position of a running web. FIG. 4 and FIG. 5 are diagrams showing other embodiments of the pneumatic circuit construction. l...Air blower 2...Refueling pump 3...Air nozzle 4...Chopper plate (dither signal generation resistance) 5
... Drive motor 6 ... Hydraulic servo valve 7 ... Air pressure converter 8 ... Air sensor 9 ... - Factory air 10 ... Servo valve 11 ... Variable throttle 12 ... Pulsation number 1 Figure 2... Fuel pump 3... Air nozzle 4... Chopper plate 5... Drive motor 9... Factory air lO... Servo valve 11... Variable throttle 12... Pulsation Showa November 25, 1963, Indication of the case, 1988 Patent Application No. 270293 2, Name of the invention, Method and device for generating dither for pneumatic hydraulic servos 3, Person making the amendment Relationship with the case Patent applicant address Tokyo 2951 Ishikawacho, Hachioimo City 4 Name: Nireco Co., Ltd. Representative: Kubo 1) Katsutoshi 4, Agent: 105 Address: 706 Hamamatsucho Diamond Heights (1), 2-2-15 Hamamatsucho, Minato-ku, Tokyo (1) 4 Figure 5 is supplemented. Ko, list of attached documents! J7 Figure Figure

Claims (6)

[Claims] (1) In a control system that includes a hydraulic servo valve operated by a pneumatic signal, a dither is generated in the pressure of the air source supplied to the pneumatic signal generator, and the dither is superimposed on the pneumatic signal to give a signal force to the spool. When determining the position of the spool in equilibrium with the force, dithering is applied to the circuit from the air source to the spool by an air circuit that includes a periodic change mechanism of air circuit resistance that rotates in conjunction with the hydraulic pump shaft of the hydraulic system. A dither generation method for a servo valve characterized by generating dither. (2) The dither generation method for a servo valve according to claim 1, wherein the air resistance periodic change mechanism is inserted into an air discharge circuit communicating with the spool. (3) The dither generation method for a servo valve according to claim 1, wherein the periodic change mechanism for the air low term is inserted into a bypass circuit communicating with the spool. (4) In a system in which the spool of a hydraulic servo valve is operated and controlled by pneumatic pressure, the spool rotates in conjunction with the oil supply pump for the hydraulic servo, and the resistance of the pipe connected to the air supply source is periodically changed using a periodic air resistance change mechanism. A dither generator for an air-operated hydraulic servo valve, which is characterized by applying pulsation to an air line by changing the direction of the air. (5) The dither generating device for an air-operated hydraulic servo valve according to claim 4, wherein the periodic change mechanism is constructed by using a chopper plate and attaching it to the drive shaft of a drive motor. (6) The dither generator for an air-operated hydraulic servo valve according to claim 5, wherein the chopper plate is constructed by being attached to a rotor or a coupling of an air blower.