JPS6085280A - Counterflow preventer for diaphragm vacuum pump - Google Patents

Abstract

PURPOSE:To reduce load when restarting by providing an orifice for allowing faint counterflow on an exhaust valve of diaphragm vacuum pump and closing the suction valve reliably upon stoppage of pump to prevent counterflow into the vacuum chamber. CONSTITUTION:Grooves 28, 28 are made in the projections 31, 31 provided on the surface of valve seat 30 of exhaust valve in suction and exhaust valves of vacuum pump to form an orifice 26 communicating between the pump chamber and the atmosphere. Upon stoppage of pump, atmospheric air will counter flow through said orifice 26 to produce the differential pressure across the vacuum chamber for closing the suction valve reliably and preventing the counterflow. Consequently, special sluice valve for preventing counterflow is not required and since the interior of pump chamber is at the atmospheric pressure level when restarting, the starting force can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a backflow prevention device for a diaphragm vacuum pump.

Conventionally, this type of air pump generally has a pump chamber equipped with a flow control valve consisting of an Il & air valve and an exhaust valve.
For example, when the pump is connected to vacuum chamber a to be evacuated as shown in the first diagram to exhaust the inside thereof, when pump b is stopped, atmospheric air flows somewhat back into chamber a through the flow control valve. Therefore, it is necessary to install a gate valve d in the connection circuit 0 to prevent this, and when restarting the pump b, if the pressure inside the pump chamber is low, starting power is required to inflate the diaphragm, which requires a large electric motor. Since the exhaust system has to be installed, there are inconveniences such as the exhaust equipment becoming expensive.

It is an object of the present invention to provide a diaphragm type vacuum pump that does not have such inconveniences, and has one or more pump chambers equipped with a diaphragm that is reciprocated by an electric motor and a flow control valve consisting of an intake valve and an exhaust valve. In the vacuum pump having the following, the remaining flow control valves other than the intake valve connected to the vacuum chamber to be evacuated are provided with an oriice that allows a small amount of fluid to flow when the valves are closed. .

To explain the embodiment of the present invention with reference to the drawings, in Figs. 2 to 4, (1) shows the pump case, and (5) shows the electric motor, and when the electric motor (5) is driven, its output is The eccentric shaft (6) integrally attached to the shaft (5a) rotates, and a pair of connecting rods (71 (71 reciprocates left and right) fitted to the eccentric six shaft (6) via bearings (6a) rotate. do.

(8) is a synthetic resin diaphragm with a central part attached to the tip of each rondo (7), and a case (1) surrounding it.
It was held between the pump heads (21), and when the Rondo (7) reciprocated, the volume of the pump chamber (9) formed in the pump head +21 was increased or decreased.The pump chamber (
9) on the side facing the diaphragm (8).
A plate-shaped flow control valve 0υ is provided through the valve 01, and behind it, an intake passage (121) is connected to the intake boat (3) via a filter, and a filter is connected to the exhaust boat (4) via the filter. For example, as shown in FIGS. 5 and 6, the control valve aυ has a horseshoe-shaped opening (141) in the valve body (11a) (a valve plate having a hole 141 formed therein). The tongue pieces (15) (15) formed inside the control valve Ql)
The air intake passage (from 12+ to the pump (
The intake valve (16) allows gas to flow into the pump chamber (9), and the exhaust valve fin controls the discharge of gas from the pump chamber (9) to the exhaust passage (+31). As shown in Figs. 7 and 8, a recess U into which the tongue piece (1!19) of the intake valve tte can fall is formed on the plate Ql, and a recess U is formed around the opening of the exhaust passage 0 of the pump head (2) as shown in Fig. 9. and a recess a9 into which the tongue aω of the exhaust valve a can fall as shown in Figure 10.
is formed. The circle (a) in Figure 7 is the gas flow hole, Ql+
(2υ is a screw (23 (2 ha) insertion hole for fixing the valve holding plate (I) to the pump head (21) together with the flow control valve I. 0 (force is the opening of the intake passage α2 of the pump head (2) and the valve holding plate (gas flow hole on the exhaust side of IQ)
The valve seat that constitutes the flow control valve aυ buried in
The tongue pieces (151) are in close contact with each other to prevent backflow of gas.The assembly structure of the control valve αD is as shown in FIG. A thin plate C3 is used to ensure particularly good contact with the valve seat (to).
I set up A.

As the volume of the pump chamber (9) increases or decreases due to the reciprocating motion of the p-rad (7) described above, the intake valve (II
Intake of gas into the pump chamber (9) through the pump chamber (9)
) through the exhaust valve (17) to the exhaust boat (4); in this case, one exhaust chamber (9a
) of the vacuum chamber to be evacuated (5a)
(to) and its exhaust bow (4a) to the intake bow (5b) of the other pump chamber (9b). The gas in the vacuum chamber (c) is connected through the pump chamber (9a).
) (9b) k-yot) 2 The pump chamber (
9b) Exhaust air) (4b) is assumed to be discharged into the atmosphere.

Therefore, the intake bow of each pump chamber (9a) (9b)
It is also possible to construct a one-stage structure in which both 5a) and 5b are connected to the vacuum chamber (2), and the exhaust bows 4a and 4b are both exposed to the atmosphere.

The above configuration is almost the same as that of a conventional diaphragm vacuum pump, and with this configuration, when the electric motor (5) is stopped and restarted, a large starting force is required if the pump chamber (9) is in a vacuum. Since the atmosphere tends to flow back into the vacuum chamber 0th floor through the flow control valve aIl when the system is stopped, it is necessary to shut off the circuit t2ω with a gate valve. The remaining flow control valves aυ, that is, the exhaust valves (17a) (17b) and the intake valve 06b) are provided with orifices +261 as illustrated in FIGS. This made it possible to prevent atmospheric backflow. To explain this further, the orifice (E) connects the groove (to) with a minute flow area such that gas does not flow when the electric motor (5) is driven to the valve seat (to) of the remaining flow control valve aυ. Even if the electric i (51) is stopped and the remaining flow control valve αυ is closed, the atmosphere will flow through each pump chamber (9) through the orifice.
a) Allowed to flow into (9b). Therefore, when each pump chamber (qa) (9b) reaches atmospheric pressure, the tongue piece Q51 of the intake valve (16a) connected to the vacuum chamber (c) has one side connected to the vacuum chamber (23) and the other side to the atmospheric pressure. Since the side becomes atmospheric pressure and receives a force due to a large pressure difference and is in close contact with the valve seat, the atmosphere is prevented from flowing back from the pump chamber (9) to the vacuum chamber (c) at the intake valve (16a). There is no need for a special gate valve to prevent backflow, and since each pump chamber (9) is also at atmospheric pressure, the diaphragm (8) can be easily expanded and contracted, and the starting force of the electric motor (5) is small. Yes, the area of the orifice (c) is determined by considering the pump capacity, flow rate, and ultimate pressure.

In this way, according to the present invention, an orifice is provided in the remaining flow control valves other than the intake valve connected to the vacuum chamber, so that when the operation of the diaphragm by the electric motor stops, the atmosphere is introduced into the pump chamber. The intake valve is closely spaced to prevent backflow of the atmosphere, there is no need to provide a gate valve, and the power required to restart the pump is also reduced, so the electric motor can be made smaller and more economical.

[Brief explanation of drawings]

Fig. 1 is a line diagram of the conventional example, Fig. 2 is a partially cutaway side view of the embodiment of the present invention, Fig. 5 is its right side view, Fig. 4 is its left side view, and Fig. 5 is the flow control FIG. 6 is a front view of the valve plate of the valve, FIG. 6 is a sectional view thereof, FIG. 7 is a front view of the inserting plate, FIG. 8 is a sectional view thereof, and FIG. Side view, 1st
Figure 0 is the X-XM cross-sectional view of Figure 9, Figure 11 is the front view of the valve seat, Figure 12 is its cross-sectional view, Figure 15 is the cross-sectional view of the orifice, and Figure 14 is the cut groove provided. Front view of valve seat, No. 15
The figure is a sectional view thereof, and FIG. 16 is an exploded perspective view of the flow control valve. (5)...1 +111111<8)...Diaphragm (9)...Pump chamber QB...Flow control valve (1
e...Intake valve aη...Exhaust valve (a)...2 people outside the orifice

Claims (1)

[Claims] In a type of vacuum pump having one or more pump chambers, which is equipped with a diaphragm that is reciprocated by an electric motor and a flow control valve consisting of an intake valve and an exhaust valve, the intake valve is connected to the vacuum chamber to be evacuated. 1. A backflow prevention device for a diaphragm vacuum pump, characterized in that the remaining flow control valves other than the above are provided with merifices that allow a small amount of fluid to flow when the valves are closed.