WO2009090775A1

WO2009090775A1 - Vacuum generation device

Info

Publication number: WO2009090775A1
Application number: PCT/JP2008/066688
Authority: WO
Inventors: Teruhiko Fujiwara
Original assignee: Koganei Corporation
Priority date: 2008-01-15
Filing date: 2008-09-17
Publication date: 2009-07-23
Also published as: JP2009166153A

Abstract

A device body (10) has an ejector (13), and the ejector (13) has a nozzle (15) and a diffuser (17) in which a suction hole (18) is formed. A supply-air flow passage (35) is formed between the nozzle (15) and a connection port (34) to which a compressed-air supply source (32) is connected. The supply-air flow passage (35) is opened and closed by a supply-air control solenoid valve (31). A suction device (43) for vacuum-sucking a workpiece (W) is connected through a vacuum pipe (44) to a vacuum flow passage (42) communicating with the suction hole (18). An air tank (40) in which the compressed air supplied from the supply-air flow passage (35) is accumulated is formed in the device body (10). The compressed air from the air tank (40) is supplied to the nozzle (15) at the beginning of suction of the workpiece by the suction device (43).

Description

Vacuum generator

The present invention relates to a vacuum generator that supplies compressed air to an ejector and generates a negative pressure by a jet of compressed air.

A vacuum generator that supplies compressed air from a nozzle to a diffuser and sucks outside air into a suction hole formed in the diffuser to generate negative pressure is also called an ejector vacuum pump or simply an ejector. A vacuum is generated using the viscosity of This type of vacuum generator has the advantage that it can be miniaturized because there is no moving part and no vacuum pump or vacuum tank is required. For example, as described in Patent Document 1, a vacuum generator is used to supply a negative pressure to a vacuum suction tool that sucks an electronic component or the like as a transported object, that is, a workpiece. A pneumatic operating device is used in a production line for manufacturing industrial products such as electronic parts, and piping for supplying compressed air to the pneumatic operating device is laid in the production line. Therefore, the ejector-type vacuum generator has an advantage that negative pressure can be supplied to the vacuum operating device using the compressed air supplied to the piping laid in the production line without laying the vacuum pump. is there.
JP 2002-103263 A

A vacuum generator having an ejector must always supply compressed air to the ejector nozzle in order to generate a vacuum. Therefore, in the vacuum generator used for sucking and transporting the workpiece, the compressed air is continuously supplied to the nozzle until the workpiece is transported after the workpiece is sucked.

In recent years, production lines for mass production of industrial products are required to reduce the consumption of compressed air, and efforts are being made to reduce the supply pressure of compressed air supplied to the production line. Therefore, the supply pressure of the compressed air supplied to the ejector from the piping laid on the production line is also reduced. When the pressure of the compressed air supplied to the ejector is reduced from 0.5 MPa to 0.4 MPa, for example, it is necessary to increase the supply flow rate to the ejector in order to obtain a predetermined degree of vacuum by the ejector. The amount cannot be reduced.

Various studies have been made to reduce the air consumption of the ejector. As a result, in a vacuum generating device for sucking and transporting a workpiece, it is necessary to increase the degree of vacuum at the initial stage of sucking the workpiece with a vacuum suction tool, but it is transported while maintaining the sucked state. It was found that the degree of vacuum at that time could be lower than the initial stage of adsorption. Therefore, after the workpiece is adsorbed, the workpiece can be adsorbed and transported even if the supply air amount is lowered from the initial stage of adsorption, so that the amount of air used by the vacuum adsorption device can be reduced.

An object of the present invention is to reduce the amount of compressed air used for operating an ejector-type vacuum generator.

The vacuum generator of the present invention is a vacuum generator that generates negative pressure air by a jet of compressed air, and has a nozzle that ejects compressed air and a suction hole that guides air sucked into the air ejected from the nozzle. An ejector provided in the apparatus main body with a formed diffuser, a supply port formed between a connection port to which a compressed air supply source is connected, and the nozzle; and the nozzle by opening the supply channel An air supply control solenoid valve for switching between an air supply state for supplying compressed air to the air supply stop state and an air supply stop state for shutting off the supply of compressed air to the nozzle by blocking the air supply flow path; A vacuum channel that is formed in the device main body and supplies a negative pressure to an adsorbing tool that vacuum-sucks a workpiece, and is provided in the device main body in communication with the air supply channel, and the air supply channel is used for the air supply control electromagnetic An air tank that accumulates compressed air under a state blocked by the air supply, and supplies the compressed air accumulated when the air supply passage is opened by the air supply control solenoid valve to the nozzle; Compressed air from the air tank is supplied to the nozzle at the initial stage of workpiece suction by the suction tool.

The vacuum generator of the present invention is characterized in that a throttle is provided between the connection port and the tank. The vacuum generator of the present invention has a flow rate sensor for detecting a flow rate of negative pressure air flowing through the vacuum flow path. The vacuum generator of the present invention opens and closes a vacuum break passage that connects the connection port and the vacuum passage, and supplies compressed air from the connection port to the vacuum passage to reduce the vacuum in the vacuum passage. A vacuum breaking electromagnetic valve that switches between a state of breaking and a state of stopping the supply of compressed air is provided. The vacuum generator of the present invention is characterized in that the air tank is formed inside the apparatus main body.

According to the present invention, since the compressed air from the air tank is supplied to the ejector nozzle in the initial stage of workpiece adsorption by the suction tool, a large amount of air is supplied to the ejector in the initial stage of workpiece adsorption. Thereby, the degree of vacuum of the suction tool in the initial stage of suction can be increased, and the workpiece can be reliably suctioned to the suction tool. After the compressed air accumulated in the air tank is released, the compressed air from the compressed air supply source is supplied to the nozzle. After the work is sucked by the sucking tool, the work can be held even if the vacuum degree of the sucking tool is lowered from the initial stage of the sucking.

Therefore, even if the flow rate of compressed air necessary for holding the workpiece is supplied from the compressed air supply source to the vacuum generator, the air tank is required at the initial stage of adsorption where the degree of vacuum of the compressed air supplied to the ejector needs to be increased. Even if the flow rate of the compressed air supplied from the compressed air supply source to the vacuum generator is reduced to the flow rate necessary for holding the workpiece by supplying a large amount of compressed air from It can be done reliably. As a result, the flow rate of the compressed air supplied to the vacuum generator can be reduced, and the amount of air consumed in the vacuum generator including the holding operation and the holding operation can be greatly reduced.

Even if the pressure of the compressed air supplied to the pneumatic piping laid on the production line for mass-produced products is reduced to reduce the amount of air used and the air pressure supplied to the vacuum generator from the pneumatic piping is reduced, the present invention Accordingly, since a large amount of air is supplied from the air tank to the ejector at the initial stage of workpiece adsorption, the workpiece can be reliably conveyed and conveyed.

Whether or not the work has been adsorbed by the adsorbing tool can be reliably determined by detecting the flow rate of the air flowing in the vacuum flow path. The flow rate of the compressed air supplied to the ejector after completion of the adsorption can be adjusted by a throttle valve, and the flow rate corresponding to the vacuum pressure required in the vacuum generator can be set to an optimum value.

It is sectional drawing which shows the vacuum generator which is one embodiment of this invention. FIG. 2 is a pneumatic circuit diagram of the vacuum generator shown in FIG. 1. It is a flow rate characteristic diagram which shows the relationship between the vacuum degree of the negative pressure air which flows through the inside of a vacuum flow path, and the suction flow rate when changing the pressure of the compressed air supplied to a vacuum generator.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, this vacuum generator has an apparatus body 10 made of a block material having a substantially square cross section. A support block 11 is attached to the apparatus main body 10 on the lower end face in FIG. 1, and the apparatus main body 10 is fixed to an installation location by the support block 11. When the support block 11 has a long dimension in a direction perpendicular to the paper surface and is mounted so that a plurality of vacuum generators are stacked on the support block 11, a plurality of vacuum generators can be assembled on the support block 11.

The apparatus main body 10 is formed with a cylindrical accommodation hole 12 that is open on one side surface and extends in the width direction, and an ejector 13 is attached to the accommodation hole 12. The ejector 13 includes a main ejector 13a and a sub ejector 13b. The main ejector 13 a has a nozzle 15 in which an inflow hole 14 is formed on the base end side, and a diffusion hole 16 is formed at the tip of the nozzle 15. The diffusion hole 16 has a tapered surface whose inner diameter increases toward the tip surface, and the compressed air supplied to the inflow hole 14 is ejected from the diffusion hole 16 while expanding. The main ejector 13 a has a diffuser 17 to which the nozzle 15 is assembled, and the nozzle 15 is fitted to the base end portion of the diffuser 17.

An annular groove is formed at the base end portion of the diffuser 17, and a plurality of suction holes 18 communicating with the inside are formed in the annular groove. A diffuser channel 19 is formed coaxially with the central axis of the nozzle 15 inside the diffuser 17, and the air around the suction hole 18 is entrained by the viscosity of the compressed air ejected from the nozzle 15, so that the suction hole 18 has a negative pressure. It becomes. The air entrained from the suction hole 18 flows downstream of the diffuser channel 19 together with the compressed air ejected from the nozzle 15. The diffuser channel 19 has an upstream reduced diameter portion 19a, a downstream diffusion portion 19b, and an intermediate straight portion 19c therebetween.

The secondary ejector 13b is formed by a cylindrical diffuser 22 in which a diffuser flow path 21 is formed, and the diffuser flow path 21 communicates with the diffuser flow path 19 of the main ejector 13a. The diffuser 22 is abutted against the downstream end face of the diffuser 17, and the downstream end of the diffuser 17 has a function of a nozzle for supplying a jet to the diffuser 22 of the sub ejector 13b. The diffuser flow path 21 has an upstream diameter-reduced portion 21a, a downstream diffusion portion 21b, and an intermediate straight portion 21c, and ambient air is present at the downstream end of the diffuser 17 of the main ejector 13a. Is formed.

Thus, the ejector 13 has the main ejector 13a and the sub ejector 13b, and the plug 23 screwed to the opening of the accommodation hole 12 is abutted against the diffuser 22, and the ejector 13 is fixed to the apparatus main body 10 by the plug 23. Has been. An exhaust port 24 is formed in the upper end surface of the apparatus body 10 in FIG. 1, and the exhaust port 24 communicates with an outlet at the downstream end of the diffuser 22. The apparatus body 10 is provided with a silencer 25, a muffler 27 is incorporated in a silencer chamber 26 formed in the silencer 25, and an exhaust port 28 is formed in the silencer 25. As a result, the compressed air that flows through the diffuser passage 21 and is discharged to the outside through the exhaust port 28 is silenced by the muffler 27 and is discharged to the outside.

An air supply control solenoid valve 31 is attached to the side surface of the apparatus body 10. A connection port 34 connected to the compressed air supply source 32 via a pipe 33 is formed in the apparatus main body 10, and this connection port 34 is connected to the air supply control electromagnetic valve 31 by an air supply passage 35 formed in the apparatus main body 10. The air supply port 36 communicates. The output port 37 of the air supply control electromagnetic valve 31 communicates with the inflow hole 14 of the ejector 13, and when a drive signal is supplied to the coil of the air supply control electromagnetic valve 31, the air supply port 36 and the output port 37. And the air supply passage 35 is opened. As a result, the compressed air flowing into the connection port 34 is supplied to the nozzle 15. On the other hand, when the supply of the drive signal to the coil of the air supply control electromagnetic valve 31 is stopped, the communication between the air supply port 36 and the output port 37 is cut off, and the air supply passage 35 is cut off. Thereby, the supply of compressed air to the nozzle 15 is stopped.

A throttle valve 38 for adjusting the opening degree of the air supply passage 35 is provided in the apparatus main body 10, and the opening degree on the upstream side of the air supply passage 35 is adjusted by the valve body 38b by rotating the adjustment screw 38a. Is done.

In the apparatus main body 10, an air tank 40 is formed in the middle of the air supply passage 35, and the air supply port 36 of the air supply control electromagnetic valve 31 communicates with the connection port 34 via the air tank 40 and the throttle valve 38. . Therefore, under the state where the communication between the air supply port 36 and the output port 37 is blocked by the air supply control solenoid valve 31, the compressed air supplied from the compressed air supply source 32 via the connection port 34 is the air tank. 40 is accumulated.

A vacuum channel 42 is formed in the apparatus main body 10 between each

suction hole

18, 18 a of the ejector 13 and a joint 41 attached to the side surface of the apparatus main body 10. A vacuum pipe 44 provided with 43 is mounted. A filter housing hole 45 is formed in the apparatus main body 10 in the middle of the vacuum flow path 42, and the filter housing hole 45 opens on the side surface of the apparatus main body 10. A cylindrical filter element 46 is incorporated in the filter accommodation hole 45, and the filter element 46 is fixed by a plug 47 attached to the opening of the filter accommodation hole 45.

Therefore, when a drive signal is supplied to the coil of the air supply control electromagnetic valve 31 to connect the air supply port 36 and the output port 37, the compressed air from the compressed air supply source 32 is supplied to the ejector 13. The compressed air is ejected from the nozzle 15 to the diffuser 17 and entrains the air around the suction hole 18 and flows into the diffuser flow path 21 of the diffuser 22 and entrains the air around the suction hole 18 a and passes through the muffler 27. The gas is discharged from the exhaust port 28 to the outside.

When the air around the suction holes 18 and 18a is sucked into the ejector 13 by viscosity, the inside of the vacuum channel 42 is in a negative pressure state, that is, a vacuum state. The vacuum in the vacuum channel 42 is guided to the suction tool 43 by the vacuum pipe 44, and the workpiece W is sucked by the suction tool 43. Thereby, the workpiece | work W is conveyed to a predetermined | prescribed position by conveying the apparatus main body 10 or the suction tool 43 by the conveying apparatus which is not shown in figure.

When the workpiece W is attracted by the suction tool 43, the suction tool 43 is brought into contact with the workpiece W or is supplied by supplying a drive signal to the coil of the air supply control electromagnetic valve 31 in a state of being brought close to the workpiece W. The air flow path 35 is opened. In the initial stage of workpiece adsorption when the air supply passage 35 is opened, the compressed air accumulated in the air tank 40 is released to the ejector 13 via the air supply control electromagnetic valve 31. Of air is supplied. As a result, the degree of vacuum of the negative pressure air supplied to the suction tool 43 via the vacuum flow path 42 is increased, and the workpiece W is reliably sucked and held by the suction tool 43.

When the compressed air accumulated in the air tank 40 is exhausted to the ejector 13, the compressed air supplied from the compressed air supply source 32 is supplied to the ejector 13 through the throttle valve 38. Therefore, since the amount of compressed air supplied to the ejector 13 is lower than the initial stage of workpiece adsorption, the vacuum degree of the vacuum flow path 42 and the suction tool 43 is reduced. However, since the workpiece W is reliably attracted and held by the suction tool 43 in the initial stage of workpiece suction, the workpiece W does not fall from the suction tool 43 even if the degree of vacuum decreases during the conveyance process.

If the energization of the coil of the air supply control electromagnetic valve 31 is stopped in order to drop the work W from the suction tool 43 after the conveyance of the work W is completed, the communication between the air supply port 36 and the output port 37 is interrupted. Thereby, the compressed air supplied from the compressed air supply source 32 is accumulated in the air tank 40. In this way, the flow rate of the compressed air flowing through the air supply passage 35 is adjusted by adjusting the opening of the throttle valve 38, and the compressed air supplied to the ejector 13 is adjusted to a flow rate that provides a required degree of vacuum in the transfer process after the workpiece is attracted. Even when the flow rate is set, the compressed air in the air tank 40 is discharged to the ejector 13 at the initial stage of workpiece suction where the suction tool 43 needs to be set at a high degree of vacuum. The total flow rate of the compressed air can be reduced as compared with the case where the air tank 40 is not used.

A vacuum breaking electromagnetic valve 51 is attached to the side surface of the apparatus main body 10 adjacent to the air supply control electromagnetic valve 31. The vacuum break solenoid valve 51 has an air supply port 53 that communicates with the connection port 34 via the branch flow path 52, and an output port 55 that communicates with the vacuum flow path 42 and the vacuum break flow path 54. When a drive signal is supplied to the coil of the vacuum breaking electromagnetic valve 51, the air supply port 53 and the output port 55 are switched to the communication state by the valve body incorporated therein, and the compressed air passes through the vacuum breaking electromagnetic valve 51. Then, the suction tool 43 is supplied via the vacuum channel 42. On the other hand, when the supply of the drive signal to the coil of the vacuum breaking electromagnetic valve 51 is stopped, the communication between the air supply port 53 and the output port 55 is cut off, and the supply of compressed air to the adsorber 43 is stopped. Therefore, when the work W is removed from the suction tool 43 after the suction tool 43 has finished sucking and transporting the work W, the supply of the drive signal to the coil of the air supply control electromagnetic valve 31 is stopped and the compressed air to the ejector 13 is stopped. When the supply is stopped and a drive signal is supplied to the coil of the vacuum breaking electromagnetic valve 51, the compressed air is supplied to the vacuum flow path 42 and the vacuum of the adsorber 43 is broken. Thereby, the workpiece | work W can be reliably removed from the suction tool 43. FIG.

In order to determine whether or not the work W has been adsorbed to the adsorbing tool 43, a flow rate sensor 56 for detecting the air flow rate in the vacuum flow path 42 is provided in the support block 11.

FIG. 3 is a flow characteristic diagram showing the relationship between the degree of vacuum of the negative pressure air flowing in the vacuum flow path and the suction flow rate when the pressure of the compressed air supplied to the vacuum generator is changed.

In FIG. 3, five types of compressed air of 0.1 MPa to 0.5 MPa are respectively supplied from the compressed air supply source 32 to the connection port 34, and negative pressure air that is generated by the ejector 13 and flows in the vacuum channel 42 for each of them. The relationship between the degree of vacuum and the suction flow rate is shown. As shown in FIG. 3, when the pressure of the compressed air supplied to the ejector 13 is changed, the ultimate vacuum is lowered when the pressure of the compressed air is lowered. However, the reduction rate of the negative pressure air flowing in the vacuum channel 42 is smaller than the pressure change of the degree of vacuum. For example, comparing the case where 0.5 MPa compressed air is supplied with the case where 0.3 MPa compressed air is supplied, 0.3 MPa is negative because the inclination angle of the flow rate characteristic becomes smaller as shown in FIG. It can be seen that the reduction rate of the compressed air is smaller than the pressure change.

Therefore, when the flow rate in the vacuum flow path 42 is detected by the flow rate sensor 56 and it is determined whether or not the work W is adsorbed to the suction tool 43, the pressure of the compressed air supplied to the ejector 13 is reduced and the supply flow rate is reduced. Even so, the suction determination can be performed with higher accuracy than when the pressure in the vacuum flow path 42 is detected by the pressure sensor to determine the suction of the workpiece W. The pressure of the compressed air in the production line is reduced in order to reduce the flow rate of the compressed air supplied to the production line by determining whether or not the workpiece W is attracted to the suction tool 43 using the flow rate sensor 56 in this way. It is possible to reliably perform the suction determination of the workpiece W even if the resistance is lowered.

The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the invention. For example, the ejector 13 includes a main ejector 13a and a sub ejector 13b. However, the ejector 13 may have a structure including only the main ejector 13a. Further, the air tank 40 may be disposed outside the apparatus main body 10.

This vacuum generator is applied to supply a vacuum to an adsorber for adsorbing and transporting electronic components and the like.

Claims

A vacuum generator that generates negative pressure air by a jet of compressed air,
An ejector provided in the apparatus main body, including a nozzle that ejects compressed air and a diffuser in which a suction hole that guides air sucked into the air ejected from the nozzle is formed;
An air supply passage formed between a connection port to which a compressed air supply source is connected and the nozzle;
Supply air control electromagnetic that switches between an air supply state in which the air supply passage is opened and compressed air is supplied to the nozzle and a supply air stop state in which the supply air passage is shut off and supply of compressed air to the nozzle is stopped A valve,
A vacuum channel that is formed in the apparatus main body in communication with the suction hole and supplies a negative pressure to a suction tool that vacuum-sucks the workpiece;
Compressed air is accumulated under the condition that the air supply passage is provided in the apparatus body in communication with the air supply passage, and the air supply passage is blocked by the air supply control electromagnetic valve, and the air supply passage is provided with the air supply passage. An air tank that supplies the compressed air accumulated when opened by the control solenoid valve to the nozzle;
A vacuum generating apparatus, wherein compressed air from the air tank is supplied to the nozzle at an initial stage of workpiece adsorption by the adsorption tool.
2. The vacuum generator according to claim 1, wherein a throttle is provided between the connection port and the tank.
3. The vacuum generator according to claim 1, further comprising a flow rate sensor for detecting a flow rate of the negative pressure air flowing through the vacuum flow path.
The vacuum generating device according to any one of claims 1 to 3, wherein a vacuum break passage for connecting the connection port and the vacuum passage is opened and closed, and compressed air from the connection port is supplied to the vacuum passage. And a vacuum breaking electromagnetic valve that switches between a state of breaking the vacuum of the vacuum flow path and a state of stopping the supply of compressed air.
The vacuum generator according to any one of claims 1 to 4, wherein the air tank is formed inside the apparatus main body.