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Description  |
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FIELD OF THE INVENTION
The present invention relates to a vacuum breaking device for breaking a
vacuum generated by an ejector pump.
BACKGROUND OF THE INVENTION
In case a vacuum is generated in an ejector pump when compressed air is
ejected into the ejector hole from the nozzle hole and air in the air
intake chamber between the holes is sucked and discharged outside the
chamber, the vacuum has to be broken by introducing the compressed air
into the evacuated system when the operation of the pump is finished.
However, the conventional method has had a disadvantage that sometimes the
compressed air escapes into the atmosphere through the ejector hole so
that an effective vacuum breaking operation is hindered.
SUMMARY OF THE INVENTION
The present invention has been made to eliminate the above-described
disadvantage of the conventional method. That is, according to the present
invention, there is provided a vacuum breaking device for an ejector pump.
The ejector pump is provided with a sealing valve operating such that when
the vacuum breaking compressed air is applied, the sealing valve shifts
due to the pressure of the compressed air to block the outlet port of the
ejector hole allowing the compressed air to be fully supplied into the
evacuated system so that residual negative pressure is securely removed.
Accordingly, an object of the present invention is to provide a vacuum
breaking device for an ejector pump, which is provided with a movable
sealing valve capable of preventing the leakage of compressed air into the
atmosphere by blocking the outlet port of the ejector pump when a vacuum
generated in a system connected to the pump is broken, whereby an
effective vacuum breaking operation is performed.
Another object of the present invention is to provide a vacuum breaking
device which is applicable to a vacuum sucking device for transferring an
article to a desired place.
BRIEF DESCRIPTION OF HE DRAWINGS
The present invention will now be described with reference to the
accompanying drawings wherein:
FIG. 1 is a perspective view of a preferred embodiment of a vacuum breaking
device for an ejector pump according to the present invention;
FIG. 2 is a vertical sectional front view of the device shown in FIG. 1;
FIG. 3 is a partial sectional view of the ejector pump shown in FIG. 1;
FIGS. 4 and 5 are plan views, respectively, illustrating an operation of a
vacuum breaking flow rate adjusting valve forming part of the device shown
in FIG. 1;
FIG. 6 is a side view of a filter forming part of the device shown in FIG.
1;
FIGS. 7 and 8 are perspective views, respectively, showing both ends of a
plunger of a vacuum generating electromagnetic valve forming part of the
device shown in FIG. 1;
FIG. 9 is a wiring diagram for driving the device according to the present
invention; and
FIG. 10 is a pnuematic circuit diagram used for the device according to the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, the vacuum breaking device of the present invention
mainly comprises a pump 1 attached on both sides thereof with a vacuum
generating electromagnetic valve 2, a filter 3, a vacuum breaking
electromagnetic valve 4 and a vacuum switch 5 through suitable sealing
members (not shown).
As shown in FIG. 2, the pump 1 is provided with an ejector block 7 having
an ejector hole 6 and a nozzle block 9 having a nozzle hole 8 both of
which blocks are located within a longitudinal aperture drilled through
the pump 1 and an air intake chamber 10 is formed between the nozzle hole
8 and the ejector hole 6. Further, on one side of the air intake chamber
10 there is provided a conical and elastic vacuum keeping valve 11 fitted
on the ejector block 7 and the chamber 10 is in communication with upper
and lower vent holes 12 and 13. As shown, the lower vent hole 13
communicates with an air intake port 14 through the filter 3 and the upper
vent hole 12 communicates with a compressed air inlet port 15 through the
vacuum breaking electromagnetic valve 4. Facing an outlet end 6' of the
ejector hole 6 there is provided a sealing valve 16 having an elastic
valve head 17 made of rubber or synthetic resin material and capable of
shifting to a position at which it blocks the outlet end of the ejector
hole 6. The cross-section of a tubular portion (right side in FIG. 2) of
the sealing valve 16 is made wider than that of the opening end 6' of the
ejector hole 16 so that when compressed air is introduced into the right
side of the valve 16, the valve 16 shifts toward the ejector hole 6
overcoming the pressure of the compressed air ejected from the ejector
hole 6 and further, when the compressed air is supplied only from the
ejector hole 6, the valve 16 shifts in a direction in which it leaves away
from the outlet end 6' of the ejector hole 6. Around the ejector block 7,
there is provided a tubular silencer 19 sandwiched between a stepped
portion of the pump body and the right side fitting portion 18. The
silencer 19 is made by sintering polypropyrene powder or of a suitable air
permeable noise suppressing material and at the outside of the silencer
19, there are formed a plurality of through holes 20 in the pump 1 as
shown in FIGS. 1 and 3 for discharge exhaust air from the ejector hole 6.
Adjacent the vent hole 12 in the upper part of the pump 1, there is
provided a vacuum breaking compressed air flow rate adjusting valve 21.
The adjusting valve 21 has an adjusting hole 22 capable of communicating
with the vent hole 12 and an engagement groove 23 on the upper surface
thereof and is prevented from slipping off the pump 1 by means of a pin 24
inserted sideward therethrough. Further, a recess 25 is formed in the side
surface of the valve 21 at a position corresponding to the pin 24 so that
the valve 21 is rotated by inserting a suitable jig such as a screw driver
into the engagement groove 23 until both ends of the recess 25 come into
contact with the pin 24 to bring about a state in which the adjusting hole
22 is in communication with the vent hole 12 (as shown in FIGS. 2 and 4)
and a state in which the adjusting hole 22 is out of communication with
the hole 12 as it stands substantially normal to the hole 12 (FIG. 5).
The filter 3 has a vent hole 26 communicating with the vent hole 13 and a
vent hole 27 communicating with the air intake port 14, and a tubular
filter element 28 is arranged between the holes 26 and 27. The filter
element 28 is formed by sintering polypropyrene powder so as to have
sufficient air permeability but it may be made of other suitable
materials. Further, one end of the filter element 28 is supported by
fixing pins 30 fitted into a cover 29 at the left side of the pump 1. The
cover 29 is fitted with a locking knob 31 and a locking plate 32 is fixed
inside the knob 31 by means of a snap-ring 33. As shown in FIG. 6, the
locking plate 32 is provided with engaging claws 36 to engage with grooves
35 formed inside the filter 3, and edges 34 engaging the pins 30. Thus,
when the locking knob 31 is rotated to the position shown by a chain-line
in FIG. 6, the engaging claws 36 of the locking plate 32 are disengaged
from the engagement grooves 35 so that the cover 29 and the filter element
28 can be removed from the filter 3 for cleaning the element 28 or
replacing it with new one. On the other hand, when the locking knob 31 is
returned to the position shown by a solid-line in FIG. 6, the filter
element 28 can be remounted. Further, the filter 3 is made of a
transparent synthetic resin material such as polycarbonate so as to make
it possible to observe if the filter element 28 is filthy.
The vacuum generating electromagnetic valve 2 has a vent hole 37
communicating with the compressed air inlet port 15 and opening in a fluid
chamber 38. The fluid chamber 38 is provided with a valve seat 39 and a
plunger 40 faces the valve seat 39. The plunger 40 has, at one end
thereof, an elastic valve head 41 made of rubber or synthetic resin
material, a pair of longitudinally extending elongated grooves 42 formed
in the outer periphery thereof and a vertical groove 43 on the end
opposite the valve head 41 so as to communicate with the grooves 42 (See
FIGS. 7 and 8). The plunger 40 is slidably fitted in a valve chamber A
formed in a tubular section of a bobbin 44 and is urged by a spring 45 in
a direction in which the valve head 41 comes into contact with the valve
seat 39. Facing the plunger 40, there is provided an inner valve seat 46
which corresponds in position to the nozzle hole 8 of the nozzle block 9.
Further, the inner valve seat 46 is fitted in a center post 47 and at one
end of the bobbin 44 facing the center post 47, there is provided a plate
upper 48. The outer peripheries of the center post 47 and the plate upper
48 are covered by a housing 49 and a solenoid 50 is received between the
housing 49 and the bobbin 44.
The plunger 40, housing 49 and center post 47 are all made of martensite
stainless steel and other magnetic materials and when the solenoid 50 is
excited, the plunger 40 is attracted to the center post 43 to shift to the
right as shown against the spring 45. Further, the electromagnetic valve 2
is provided with a power supply terminal 51, a connecting hole 52 and a
lighting section comprising a LED element 53 and an acrylic resin lens 54
arranged outside the former and lighting up at the time of power supply.
At the outside of the electromagnetic valve 2 there is provided a manual
operation button 55 which has a large-diametered portion therein
positioned in the fluid chamber 38 and an operating rod 57 extending
toward the plunger 40 through the valve seat 39. As shown, the operating
rod 57 passes through a small hole 58 drilled in the valve head 41 and
when the button 55 is pressed, the top end of the operating rod 57 comes
into contact with the bottom of the valve head 41 so that the plunger 40
shifts to the right thereby opening the valve hole. Further, when the
button 55 is released, compressed air acts on the large-diametered portion
56 of the button so that the button moves to the left to assume its
original position.
The vacuum breaking electromagnetic valve 4 is of the same structure as the
vacuum generating electromagnetic valve 2 so that parts of the valve 4
corresponding to those forming the valve 2 are designated by the same
reference numerals each, however, added with the letter "a" throughout the
drawings for the sake of convenience of illustration. Further, an inner
valve seat 46a faces the sealing valve 16 and communicates with the vent
hole 12 of pump 1 through the flow rate adjusting valve 21.
The vacuum switch 5 is in communication with the air intake port 14 through
a flow passage 59 and as is well known, opens and closes so as to control
the vacuum generating electromagnetic valve depending on the degree of
vacuum acting on the air intake port 14.
The solenoid 50 of the vacuum generating electromagnetic valve 2, the
solenoid 50a of the vacuum breaking electromagnetic valve 4; and the
vacuum switch 5 are connected to a control device 60 connected to a power
source E as shown in FIG. 9 and operates in the following manner:
Referring to FIG. 10 which shows a pneumatic circuit diagram and FIG. 2,
the valve seat 39 is shown contacting with the valve head 41 to close the
valve hole, no compressed air is supplied to the nozzle hole 8 but when
the solenoid 50 of the electromagnetic valve 2 is excited, the plunger 40
shifts to the right to open the valve hole so that the compressed air
enters the elongated grooves 42 of the plunger 40 from the air inlet port
15 via the vent hole 37 and the inner valve seat 46, thereby sucking and
discharging air from the air intake chamber 10. Consequently, the system
including the vent holes 13, 26, the filter 28 and the air intake port 14
is evacuated. Therefore, if, for example, a vacuum disk 61 of a vacuum
sucking device is connected to the air intake port 14 through the conduit
62, the pressure in the disk 61 is reduced enabling an article 63 to be
attracted to the disk for transferring it to a desired place. When a
predetermined negative pressure is reached in the evacuated system, the
vacuum switch 5 operates to release the excitation of the solenoid 50 and
the plunger 40 shifts to the left by the action of the spring 45 to close
the valve hole so that the injection of the compressed air is stopped but
since the system is kept at a predetermined negative pressure, the
consumption of the compressed air is saved. When the degree of vacuum
decreases due to the leakage of air, the vacuum switch 5 senses it to
allow the compressed air to be re-ejected again thereby increasing the
degree of vacuum in the system.
After transferring the article 63 to the desired place, the excitation of
the solenoid 50 of the vacuum generating electromagnetic valve 2 is
released and when the solenoid 50a of the vacuum breaking electromagnetic
valve 4 is excited, the plunger 40a shifts to the left to open the valve
hole so that the compressed air is supplied to the air intake port 14 from
the air inlet port 15 via the vent holes 37a and 12 thereby cancelling the
negative pressure in the sucking disk 61. In this case, the compressed air
tends to flow into the atmosphere from the ejector hole 6 but the vacuum
breaking compressed air has already acted on the sealing valve 16 before
it reaches the vent hole 12 so that the sealing valve 16 moves to the left
by overcoming the resistance of the injected compressed air from the
ejector hole 6 thereby blocking the outlet end 6' and preventing the
compressed air from flowing through the ejector hole. Accordingly, the
compressed air is supplied to the air intake port 14 without any loss,
which results in the advantages that the negative pressure can be released
quickly and securely, the article transfer operation can be securely
performed and the amount of consumption of the compressed air can be
minimized. The feeding time and amount of compressed air can be adjusted
by the control device 60 and the flow rate adjusting valve 21.
Further, it should be noted that the solenoids 50 and 50a may be
substituted with the manual operation buttons 55 and 55a.
As described above, the present invention has advantages that when a vacuum
is broken, the vacuum sucking action is instantaneously released without
any loss of the compressed air and therefore, the article transfer
operation can be efficiently performed.
It should be noted that although the present invention has been described
based on a preferred embodiment thereof, various modifications and
alterations can be made without departing from the spirit and scope of the
invention.
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