JPH0571471A - Oil-free vacuum pump - Google Patents

Abstract

(57) [Summary] [Purpose] An oil-free vacuum pump with high speed, large exhaust speed, and good ultimate vacuum [Constitution] When piston 12 moves to the right, solenoid valve 1
6 and 19 are opened, and the solenoid valves 17 and 18 are closed, so that the gas is sucked from the solenoid valve 16 and discharged from the solenoid valve 19. When the piston 12 moves to the left, the solenoid valves 16 and 19 are closed,
The solenoid valves 17 and 18 are opened, and the gas moves from the left of the piston 12 to the right. By repeating this, the suction pipe side gradually becomes a vacuum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-free vacuum pump for exhausting gas in an oil-free state in a semiconductor manufacturing apparatus, an apparatus for handling corrosive gas, an apparatus for handling gas that is dangerous to the human body, and the like.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a conventional example of an oil-free vacuum pump called an opposed oil-free reciprocating vacuum pump, and FIGS. 9 (a) and 9 (b) are suction valves of the conventional example shown in FIG. It is a development view showing the structure of a discharge valve. The motor 50 drives the crank portion 52 together with the flywheel 51, and simultaneously drives the pistons 60, 70 outwardly or inwardly via the shafts 68, 78 (FIG. 8 shows the case of being driven most outward). Shows the dead point). Piston 6
0 and 70 are sealed to the inner wall surfaces of the left and right cylinders by piston rings 69 and 79, respectively. The piston rings 69 and 79 are made of resin having self-lubricating property. The bellows 64 and 74 seal the oil on the crank part 52 side so as not to leak to the pistons 60 and 70 side. When the pistons 60 and 70 move inward from the state shown in the figure, that is, toward the bottom dead center, the intake valve 61 is opened, the exhaust valve 62 is closed, and the exhaust valve 63 is opened in the left cylinder portion, so that the intake air flows in the direction of arrow X And the gas held until then is discharged to the pipes 65 and 75. On the other hand, in the right cylinder part, the intake valve 71 is closed and the exhaust valve 72 is opened.
The exhaust valve 73 is closed, and the gas on the left side of the right cylinder part moves to the right side of the right cylinder part.

Next, when the pistons 60 and 70 move from the bottom dead center to the top dead center, the intake valve 61 of the left cylinder portion is closed, the exhaust valve 62 is opened, and the exhaust valve 63 is closed, so that the left cylinder portion is left. The inhaled gas moves to the right side of the left cylinder part.
On the other hand, the intake valve 71 of the right cylinder portion is opened, the exhaust valve 72 is closed, and the exhaust valve 73 is opened, so that the gas sucked into the right cylinder portion is exhausted in the direction of arrow Y.

The intake valves 61, 71 and the exhaust valves 62, 63, 72, 73 of the conventional oil-free vacuum pump are petal-shaped seat plates 84, as shown in FIGS. 9 (a) and 9 (b), respectively. 94 is sandwiched between the guide plates 83 and 85 or the guide plates 93 and 95, and the bolts 86 and 96 and the nut 8
It is formed as a self-supporting valve fixed with 1, 82, 91 and 92. These valves have a structure in which the seat plate automatically opens and closes due to the pressure difference between the suction side and the discharge side.

[0005]

The above-described conventional oil-free vacuum pump uses a self-supporting valve that sandwiches a petal-shaped seat with guide plates from both sides as an intake valve and an exhaust valve, and opens and closes between both sides of the seat. Depends on the differential pressure of.
Therefore, when the pressure difference between the front and the rear of the self-supporting valve is below a certain level, opening and closing of the valve becomes difficult, and the ultimate vacuum is limited to 0.1 Torr. Also, since this self-supporting valve opens and closes due to the vertical movement of the seat, there is a physical limit to the opening and closing of the valve, and it is impossible to follow the seat at a too high speed (about 1200 rpm), and the durability of the seat. There was a problem such as there being no stroke, and the stroke could not be taken.

In view of the above problems, it is an object of the present invention to provide an oil-free vacuum pump that uses a solenoid valve instead of a self-standing valve.

[0007]

The oil-free vacuum pump of the present invention is synchronized with the intake or exhaust operation of the pump,
It has a solenoid valve for intake and a solenoid valve for exhaust that respectively perform intake and exhaust.

Preferably, in the solenoid valve, two exciting coils are arranged adjacent to each other in an annular space of a container having a double-cylindrical airtight structure coaxially with the container, and one of the two exciting coils is provided. Is selectively excited to drive a moving element that is coaxially and movably arranged with the two exciting coils, and a solenoid valve is opened and closed by a valve member connected to the moving element.

More preferably, in the solenoid valve, an exciting coil is arranged coaxially with the container in an annular space of a container having a double-cylindrical airtight structure, and is arranged movably coaxially with the exciting coil. A spring member is provided for holding the installed moving element outside the region of the exciting coil when the exciting coil is not excited, and the exciting coil is excited to open and close the solenoid valve by the valve member.

Alternatively, in the solenoid valve, an exciting coil is arranged coaxially with the container in an annular space of the container having a double-cylindrical airtight structure, and is arranged so as to be movable coaxially with the exciting coil. Attach the valve member and suction plate to the shaft,
When the exciting coil is not excited, a spring member that holds the attracting plate away from the exciting coil is provided, and the exciting coil is excited to open and close the solenoid valve by the valve member.

[0011]

The solenoid valve for intake and exhaust is used for intake or exhaust operation of the pump, for example, movement of the piston in the cylinder,
Since the intake and the exhaust are performed in synchronization with, the valve operation is accurately controlled without depending on the pressure difference across the valve.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing an opposed oil-free reciprocating vacuum pump (hereinafter abbreviated as vacuum pump) which is a first embodiment of the oil-free vacuum pump of the present invention, and FIG. 2 is an intake valve of FIG. FIG. 16 is an enlarged explanatory view showing 16 in detail.

A piston (12) is driven by a motor (not shown) via a piston rod (14) between the top dead center and the bottom dead center in the left and right inside the cylinder (11). A piston ring 13 slidably seals between the inner wall of the cylinder 11 and the piston 12. The bellows 15 seals between the cylinder 11 and the piston rod 14 so that oil or the like on the drive side does not enter the cylinder 11.

When the piston 12 moves from left to right, the intake valve 16 is open and the exhaust valve 17 is closed.
8 is closed and the exhaust valve 19 is open. Therefore, the gas is sucked from the intake pipe 21 to the left side of the piston 12 through the intake valve 16, and the gas is exhausted to the exhaust pipe 23 from the right side through the exhaust valve 19. On the contrary, when the piston 12 moves from right to left, the intake valve 16 and the exhaust valve 19 are closed, the exhaust valve 17 and the intake valve 18 are opened, and the gas in the cylinder 11 on the left side of the piston 12 is connected to the connecting pipe. It is sent to the right side of the piston 12 via 22 and these operations are repeated again. As a result, the suction pipe 21 side becomes a vacuum.

Intake valve 1 which is a solenoid valve in the above process
6, 18 and the exhaust valve 17, 19 of the intake valve 16 will be described in more detail with reference to FIG. The contents of the other valves are substantially the same, so detailed description thereof will be omitted. Whether the movement of the piston 12 is in the right direction or the left direction is determined by the control unit 30 using the output of the photo sensor 31 (photoelectric sensor) attached to the shaft that rotates in the arrow R direction in conjunction with the motor and the piston rod 14. To do.

The coil portion 16 ₀ contains the exciting coils 16 ₁ and 16 ₂ surrounded by the yoke 16 ₉ and is fixed to the mounting member 16 ₈ . The mover 16 ₃ is held along the axis of the coil portion 16 ₀ so as to be slidable between the exciting coils 16 ₁ and 16 ₂ by a predetermined distance. From the moving element 16 ₃ to the connecting shaft 16 ₄
Extends and the seat plate 16 ₅ is fixed to the tip thereof. The seat plate 16 ₅ faces a through hole having a diameter smaller than that of the seat plate 16 ₅ provided in the valve seat plate 16 ₆ . The valve seat plate 16 ₆ is connected to the mounting member 16 ₈ . In FIG. 1, when the piston 12 moves to the right, the exciting coil 16 ₂ is excited by the control unit 30 and the moving element 1 moves.
6 ₃ is drawn to the side of the exciting coil 16 ₂ to form a gap between the seat plate 16 ₅ and the valve seat plate 16 _6, and the gas is indicated by the arrow A.
Is sucked into the cylinder 11 from the intake pipe 21 in the direction of. When the piston moves to the left, the exciting coil 16 ₁ is driven by the control unit 30, and the mover 16 ₃ moves the exciting coil 1
The seat plate 16 ₅ is pulled toward the 6 ₁ side and abuts on the O-ring 16 ₇ mounted around the through hole of the valve seat plate 16 ₆ .
The gas is prevented from flowing backward from the cylinder 11 to the intake pipe 21.

Next, a more specific second embodiment of the intake valve will be described with reference to FIG.

A seat plate 26 for opening and closing the gas passage_Five Is 1
Shaft 26 attached to the end _Four But cylindrical magnetism
Axial center of shield container 24 (abbreviated as container 24)
Each end of the container 24 is arranged so as to penetrate therethrough.
Is attached to the center of each end plate 25 that closes
Bearing 26₈ Is held slidably. Also,
Inside the container 24, a double circle made of magnetic material is coaxial with it.
A cylindrical vacuum container 27 is installed inside the
Inside the pair of annular exciting coils 26₁ , 26₂ Is average
They are installed in rows. In addition, the inner peripheral wall of the vacuum container 27
Surface is shaft 26_Four Are surrounded with a space
In the space of the ₃ Can freely reciprocate
Placed on the shaft 26_FourIs fixed.

A current introduction terminal (not shown) for supplying a current is attached to each of the exciting coils 26 ₁ and 26 ₂ through the peripheral wall of the container 24. This terminal has a leaktight structure.

The vacuum container 27 containing the exciting coils 26 ₁ and 26 ₂ is made of a magnetic material and forms a magnetic circuit for these coils 26 ₁ and 26 ₂ . When the gas passage port is closed, by supplying a current to the exciting coil 26 ₂ , the mover 26 ₃ is drawn toward the exciting coil 26 ₂ side, and the seat plate 26 ₅ fixed to one end of the shaft 26 ₄ Is applied to the O-ring 26 ₇ of the valve seat plate 26 ₆ .

When the gas passage port is opened, the other exciting coil 26 ₁ which is farther from the moving element 26 ₃ is
By switching the supply of the electric current from the exciting coil 26 ₂ , the mover 26 ₃ is attracted to the exciting coil 26 ₁ , and this and the one sheet plate 26 ₅ are moved in the same direction.

Next, a third embodiment of the present invention will be described with reference to FIG. This embodiment is a modification of those shown in FIG. 3, the excitation coil 26 ₀ is attached only one. When the mover 26 ₃ is pulled to the position of the exciting coil 26 _0, the seat plate 26 ₅ attached to one end of the shaft 26 ₄ is pressed against the valve seat plate 26 ₆ side of the cylinder body to pass the gas passage. Close it.

Further, the seat plate 26_Five Is installed
Magnetic shield container 24 on the opposite side of ₁ The end plate 25 of
Mover 26₃ To form a space in the longitudinal direction
Support 24 having a hollow cylindrical shape₂ Fixed
This support 24₂ End of shaft and shaft 26_Four End and
A spring member 28 such as a coil spring is attached between the shaft 26 and_Four
Is placed coaxially with the exciting coil 26₀ Is excited
When not present, the repulsive force of the spring member 28 causes the spring member 28 of FIG.
As indicated by the chain double-dashed line, the shaft 26_Four But the mover 26₃ When
Together support 24₂The solenoid valve is not opened.
It Therefore, the exciting coil 26₀ Is excited,
As shown by the solid line, the mover 26₃ Is the repulsive force of the spring member 28.
Against the excitation coil 26₀ Attracted by the shaft
26_Four Seal plate attached to 26_Five To the cylinder body side
It is pressed and the gas passage is closed.

Mochi theory, exciting coil 26₀ And the spring member 2
8 is reversed and the shaft 26 _Four But the spring member 28
Seat plate 26 due to the anti-repulsive force of_Five Press to close the passageway
Holding the state of the excitation coil 26₀ Is excited,
Seat plate 26_Five Can be pulled up to open the passageway
It is possible.

The advantage of the third embodiment of the present invention over the first embodiment is that since there is one exciting coil, the drive circuit can be simplified and the amount of gas that can be generated from the exciting coil can be reduced. It is possible to halve it.

A fourth embodiment will be described with reference to FIG. The present embodiment is an example of an intake valve. Shaft 3
A seal plate 36 ₅ is attached to the 6 ₄ at the lower end,
The attraction plate 36 ₉ is located in the middle near the exciting coil 36 _0.
Is installed. By a compression spring 38 which is fixed to the end face by the suction plate 36 ₉ and the magnetic circuit 34 and the Teflon sleeve 39, the suction plate 36 ₉ and the seal plate 36 ₅ excitation coil 3
6 ₀ when no current is flowing through the each excitation coil 36 ₀
And the valve seat plate 36 away from the _6, an open state.

[0028] When the current flowing through the exciting coil 36 _0, by the excitation coil 36 ₀ attract the attraction plate 36 _9, sheet plate 36 are connected by a shaft 36 _4
5 is pressed against the valve seat plate 36 _6, passage is closed.

The fifth embodiment will be described with reference to FIG. This embodiment is an example of an exhaust valve. A seal plate 46 ₅ is arranged between the exciting coil 46 ₀ and the gas passage port,
It is attached to the lower end of the shaft 46. At the upper end of the shaft 46 that passes through the center of the exciting coil 46 _0, the attracting plate 46 ₉
Is installed. By the attraction plate 46 ₉ and the magnetic path 44 and the compression spring 48 whose end face is fixed by the Teflon sleeve 49, the attraction plate 46 ₉ and the seat plate 46 ₅ are operated by the compression spring 48 when no current is flowing to the exciting coil 46 ₀ . each excitation coil 46 by repulsion ₀ and the valve seat plate 46
_{It is} separated from ₆ , and the gas passage is open.

When a current flows through the exciting coil 46 ₀ ,
The attraction plate 46 ₉ is attracted to the exciting coil 46 ₀ , and the seat plate 46 ₅ fixed to the shaft 46 is pressed against the valve seat plate 46 ₆ to close the gas passage.

In the case of the third and fourth embodiments, the suction plate 46 ₉
May be a martensitic iron material or a permanent magnet.

In the fourth and fifth embodiments of the present invention, the magnetic path 34, which is a container made of a magnetic material and having an inner diameter of 100 mm,
200 electric wires with a wire diameter of 0.8 mm inside the 44 environmental spaces
After arranging the exciting coil configured by winding ~ 300 times,
The outer peripheral portion is sealed and covered with the magnetic shield containers 34 and 44 and the sealing plates 34 ₁ and 44 ₁ , and then an inert gas is sealed inside and sealed.

Shafts 36 ₄ and 46 ₄ were passed through the centers of the exciting coils 36 ₀ and 46 ₀ , and a disc having a diameter of 60 mm and a thickness of 2 mm was fixed to the tip thereof. The gas passage has a diameter of 5
It was set to 0 mm.

When the gap between the adsorption plate and the magnetic path during energization was 0.5 mm, the opening / closing operation time was 5 msec or less at R = 3Ω, 24V, 6.6A or more. The stroke was 2.5 mm, but if a permanent magnet is used for the attraction plate, the stroke is 10 mm.
It is possible up to mm. At this time, the sealing performance of the solenoid valve showed good results, and it was confirmed by oscilloscope that chattering was not performed at all. The ultimate vacuum was improved to 10 ^-2 Torr.

The sixth embodiment will be described with reference to FIG. The seal plate and the valve seat plate are deformed so as to face each other at a predetermined angle. This deformation has the advantage of increasing the conductance in the molecular flow pressure region.

In the above-mentioned embodiments, the reciprocating vacuum pump has been explained as a basis, but the present invention is not limited to this, and may be a vane type vacuum pump, for example. In this case, the electromagnetic valves at the intake port and the exhaust port may be operated according to the intake timing and the exhaust timing accompanying the rotation of the rotor. Also in the case of a claw type or diaphragm type vacuum pump, the solenoid valves at the intake port and the exhaust port may be operated in accordance with the intake timing and the exhaust timing. In the case of the scroll type vacuum pump, the solenoid valve can be provided only with the exhaust port, and the intake port does not necessarily require the solenoid valve.

[0037]

As described above, according to the present invention, a solenoid valve is provided for intake and exhaust of a pump, and each solenoid valve is appropriately operated in synchronism with intake and exhaust operations, whereby the pressure difference between the front and rear of the valve is increased. It is possible to provide a high-performance oil-free vacuum pump which has a high opening / closing speed, a high response, is accurate, has a long service life, and is highly reliable without depending on.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an opposed oil-free reciprocating vacuum pump which is a first embodiment of an oil-free vacuum pump of the present invention.

FIG. 2 is an enlarged explanatory view showing the intake valve 16 of FIG. 1 in detail.

FIG. 3 is a sectional view specifically showing the structure of the second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing a sixth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a conventional example.

9 (a) is a development view showing the conventional intake valve of FIG. 8. FIG. FIG. 9B is a development view showing the conventional exhaust valve of FIG. 8.

[Explanation of symbols]

 11 Cylinder 12 Piston 13 Piston Ring 14 Piston Rod 15 Bellow 16,18 Intake Valve 17,19 Exhaust Valve 21 Intake Pipe 22 Connecting Pipe 23 Exhaust Pipe

Claims (4)

[Claims] 1. An oil-free vacuum pump having an electromagnetic valve for intake and an electromagnetic valve for exhaust that respectively perform intake or exhaust in synchronization with the intake or exhaust operation of the pump. 2. The electromagnetic valve is arranged such that two exciting coils are arranged adjacent to each other in an annular space of a container having a double cylindrical airtight structure and coaxially with the container, and one of the two exciting coils is provided. 2. The electromagnetic valve is selectively excited by driving the moving element coaxially and movably arranged with the two exciting coils to open and close the electromagnetic valve by the valve member connected to the moving element. Oil-free vacuum pump. 3. The electromagnetic valve has an exciting coil arranged coaxially with the container in an annular space of a container having a double-cylindrical airtight structure, and arranged so as to be movable coaxially with the exciting coil. 2. A spring member is provided for holding the moved slider outside the region of the exciting coil when the exciting coil is not excited, and the exciting coil is excited to open and close the solenoid valve by the valve member. Oil-free vacuum pump. 4. The electromagnetic valve has an exciting coil arranged coaxially with the container in an annular space of a container having a double-cylindrical airtight structure, and arranged so as to be movable coaxially with the exciting coil. A valve member and a suction plate are attached to the shaft, and a spring member is provided to hold the suction plate away from the excitation coil when the excitation coil is not excited, and the suction coil is excited by the excitation coil. 4. The oil-free vacuum pump according to claim 3, wherein the solenoid valve is opened and closed by a valve member that moves at the same time by pulling the valve toward the exciting coil.