JP4394249B2 - Reciprocating vacuum pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating vacuum pump, and more particularly to a vacuum pump that can be used as a dry pump instead of an oil rotary pump.
[0002]
[Prior art]
In recent years, vacuum has been used in all industrial fields, but most roughing pumps used to generate a vacuum with a pressure of about 1 Pa by exhausting from atmospheric pressure are oil rotary pumps. However, the oil rotary pump has the disadvantage that the oil vapor flows back to the high vacuum side and lowers the quality of the vacuum system, so recently a dry pump that does not use oil or grease has been proposed instead of the oil rotary pump. Some of them have already been commercialized.
[0003]
Among the proposed dry pumps, reciprocating pumps include piston pumps, diaphragm pumps, and bellows pumps. The piston pump is a pump that reciprocates a piston in a cylinder having an intake valve and an exhaust valve to compress and transfer a low-pressure side gas to a high-pressure side. A diaphragm pump reciprocates a shallow bowl-shaped diaphragm made of a thin elastic body instead of a piston, and changes the volume surrounded by this and a casing to perform a pumping action. A diaphragm pump does not require a sliding portion, but generally it is difficult to take a large volume change. In addition, in the “bellows pump” disclosed in Japanese Patent Application Laid-Open No. 11-159463 by the applicant of the present application, the bellows pump disclosed by the present inventors does not have a sliding portion, and the volume that can be transferred by one reciprocating motion is larger than that of a diaphragm pump Is also significantly larger.
[0004]
A reciprocating vacuum pump is generally manufactured to connect a plurality of pump chambers to obtain a predetermined ultimate pressure, but to prevent backflow at the intake and exhaust ports of each pump chamber. A valve is essential. However, many of the valves used in these systems open and close with a pressure difference between both sides of the valve plate, and the valve plate does not open and close when the differential pressure is below a limit pressure of about several hundred Pa. Therefore, the ultimate pressure of a reciprocating vacuum pump using this type of valve is usually about several hundred Pa.
[0005]
The above bellows pump, some piston pumps, and diaphragm pumps open and close with an external force in synchronism with the reciprocating motion of the bellows, piston, and diaphragm so that the valve opens and closes even below a limit pressure of several hundred Pa. There are two types of valves that can be driven: mechanical methods using cams, etc., and electromagnetic methods combining solenoid coils and ferromagnetic materials (or permanent magnets). I hated it.
[0006]
On the other hand, the applicant of the present application disclosed in Japanese Patent Application Laid-Open No. 11-287187 is a reciprocating vacuum pump provided with a drive unit that opens and closes a valve plate even when the pressure difference is below a limit pressure of about several hundred Pa. did. FIG. 13 is a cross-sectional view of the intake port portion of the pump chamber 110 of the bellows pump shown as the embodiment, and is shown together with the intake valve 120. That is, the intake valve 120 of the pump chamber 110 opens and closes the valve plate 142, the moving coil 146 wound around the bobbin 144 at the lower end of the shaft 143, the permanent magnet 147 that generates a magnetic flux crossing the moving coil 146, and the yokes 148 and 149. Is configured as a drive unit 140, and the side wall 119 of the pump chamber 110 is expanded around the rotation center 118, and the direction of direct current flowing through the moving coil 146 is synchronized with the expansion and contraction of the inner volume to be folded. By changing, the flow path 123 is opened and closed by the valve plate 142.
[0007]
[Problems to be solved by the invention]
In the pump chamber 110 having the intake valve 120 and the similar exhaust valve, the movable part including the valve plate 142 is made to have a weight of several g or less.^Five A vacuum pump that operates in a pressure range of Pa to 1 Pa can be formed, and is extremely useful as a small-sized, low-cost dry vacuum pump that replaces the oil rotary pump, as shown in FIG. Since the drive unit 140 is provided in the mounting short tube 121 that serves as a gas flow path, the drive unit 140 provides resistance during exhaust, and the valve plate 142 includes the shaft 143 and the umbrella portion 144a of the bobbin 144. Since the other end of the suspension 145 is attached to the holding metal 133, the movable part including the valve plate 142 is made lightweight. However, there is a slight time lag between the switching of the current direction in the moving coil 146 and the actual opening and closing of the valve plate 142.
[0008]
The present invention has been made in view of the above-described problems, and includes a valve plate that reliably opens and closes even when the pressure difference between both sides of the valve plate is less than a limit pressure of about several hundred Pa, and further, an actuator that opens and closes the valve plate It is an object of the present invention to provide a small-sized and low-cost reciprocating vacuum pump that is outside the gas flow path and does not cause exhaust resistance.
[0009]
[Means for Solving the Problems]
  According to the present inventionThe reciprocating vacuum pump is
A first side wall formed with an air inlet and an air outlet; a second side wall that is rotated with respect to the first side wall; and a convolution that faces the center of rotation of the second side wall. And a pump chamber whose internal volume is expanded or reduced by expansion or convolution of the convolution part accompanying the rotation of the second side wall,
  A first valve seat formed at the intake port, a first valve plate that can be separated from and seated on the first valve seat, and urging the first valve plate toward the first valve seat A first spring, a first rod having a ferromagnetic material, a first permanent magnet magnetically coupled to the ferromagnetic material, and the first permanent magnet in the length direction of the first rod A first actuator that moves the first rod in the length direction by displacing the first rod, and the first actuator causes the first actuator to be inhaled when the internal volume of the pump chamber is expanded. An intake valve mechanism capable of separating the first valve plate from the first valve seat against the bias of the first spring by moving the rod in the length direction;
  A second valve seat formed at the exhaust port, a second valve plate that can be separated from and seated on the second valve seat, and the second valve plate are urged toward the second valve seat. A second spring, a second rod having a ferromagnetic material, a second permanent magnet magnetically coupled to the ferromagnetic material, and the second permanent magnet in the length direction of the second rod. A second actuator that moves the second rod in the length direction by displacing the second rod, and the second actuator causes the second actuator to be exhausted when the internal volume of the pump chamber is reduced. An exhaust valve mechanism capable of moving the rod in the length direction to separate the second valve plate from the second valve seat against the bias of the second spring; Have.
  Such a reciprocating vacuum pump is 10⁵In the pressure range from about Pa to about 1 Pa, the intake valve and the exhaust valve are accurately opened and closed accurately, and the actuator is outside the gas flow path and does not have exhaust resistance, resulting in a small dry pump with good exhaust performance. .
[0010]
  Also,In such a reciprocating vacuum pump, when the valve plate is closed, the valve plate is easily pressed against the valve seat by a spring, and when the valve plate is opened, the valve plate is easily actuated by an actuator through a rod against the biasing by the spring. And is opened and closed with high accuracy.
[0011]
  In the reciprocating vacuum pump, the first and second actuators are electromagnetic actuators including a solenoid coil, a rod-shaped movable iron core (ferromagnetic material), and a return coil spring that urges the rod-shaped movable iron core. The rod-shaped movable iron core is resisted against the biasing of the return coil spring by turning on / off the direct current flowing through the solenoid coil in synchronization with the expansion and contraction of the internal volume of the pump chamber. It may be moved in the length direction of the rod.Such a reciprocating vacuum pump can open and close the valve plate with high accuracy and time lag.ProduceYou can control without.
[0012]
  In the reciprocating vacuum pump, a plurality of the pump chambers are connected in series, and exhaust from the exhaust port of the adjacent upstream pump chamber is sucked into the intake port of the downstream pump chamber. And, when the pump chamber on the upstream side is in the contraction period of the internal volume, the pump chambers on the downstream side may be operated in opposite phases so as to be in the expansion period of the internal volume.Such a reciprocating vacuum pump can provide a relatively large gas transfer amount to the bellows serving as a pump chamber, and thus can be a vacuum pump having excellent exhaust performance.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the reciprocating vacuum pump according to the present invention includes a spring that presses the valve plate against the valve seat with a small predetermined force when the valve is closed, and a ferromagnetic material at one end. A rod that separates the valve plate from the valve seat against the bias of the spring by the other end when the valve is opened, and an atmospheric side magnetically coupled to the ferromagnetic body of the rod through a vacuum wall If the pressure difference of the gas generated on both sides of the valve plate is larger than the limit pressure of about several hundred Pa, the valve plate is mainly used. When the pressure difference is smaller than the limit pressure, the valve plate is moved by the spring and the actuator in the same direction as the movement direction of the valve plate due to the pressure difference.
[0014]
To open and close the valve plate with the pressure difference even when the pressure difference between both sides of the valve plate is slightly larger than the limit pressure, the movable part including the valve plate and its rod is as light as possible and when closed The force that presses the valve plate against the valve seat is required to be as small as possible. From such a viewpoint, the pressing force of the valve plate when there is no gas pressure difference on both sides of the valve plate is 5 × 10.^-2N or less is desirable. In order to press the valve plate against the valve seat with such a pressing force, the movable part including the valve plate inevitably needs to be 5 g or less in weight. Therefore, at least the valve plate is required to be made of a synthetic resin or a metal having a small specific gravity.
[0015]
The pressing force as described above can be easily obtained by a spring, and a coil spring is most preferable in terms of ease of intervention. That is, by inserting a coil spring having a known elastic constant between the back surface of the valve plate and a support portion provided at a position slightly separated from the back surface, the valve plate can be uniformly pressed to the valve seat with a predetermined force. Can do. Of course, there is no problem in obtaining a predetermined pressing force by other methods. Furthermore, by reducing the weight of the movable part including the valve plate and its rod, the actuator that opens and closes the valve plate can be reduced in size.
[0016]
The valve plate may be directly coupled to the rod, but the force required for the spring that presses the valve plate against the valve seat increases by the amount of the rod, so the other end of the rod and the valve plate It is desirable that they are connected with play or are independent. That is, as shown in FIGS. 6 and 10, which will be described later, when the valve is closed, the valve plate is pressed against the valve seat by a spring when the valve plate and the rod are not in direct contact, and when the valve is opened, the rod By configuring each member so that the valve plate is pushed down or lifted away from the valve seat against the biasing of the spring by the other end of the spring, the spring force required to press the valve plate against the valve seat is also small. In addition, the actuator for moving the rod up and down is also downsized. When the valve plate is pulled up and separated from the valve seat, the rod and the valve plate must be connected, so it is necessary to connect the valve plate and the rod with play, and such connection 10 may be any other method than the rod-shaped connecting portion shown in FIG. 10 in which the lower end of the rod is loosely inserted to prevent the rod from being removed. For example, the lower end of the rod, the valve plate, Can also be obtained by linking them in a chain.
[0017]
The ferromagnetic material attached to one end of the rod may be joined on the end surface, or may be fitted in a ring shape on the outer peripheral surface of the one end. The rod is preferably moved within a cylinder-shaped guide made of a vacuum wall. In addition, since it is necessary to be light in order to be moved smoothly by the magnetically coupled atmospheric permanent magnet, it is desirable to use a synthetic resin or a metal with a low specific gravity. Further, in order to move the rod without shaking, it is necessary to reduce the clearance between the outer peripheral surface of the rod and the inner surface of the cylinder-shaped guide to such an extent that frictional resistance does not occur. It is desirable to provide a ventilation groove between both ends of the rod so as not to cause gas compression with the top surface of the rod.
The permanent magnet on the atmosphere side that moves the rod together with the ferromagnetic material may be in the shape of one or a plurality of rods parallel to the rod, but is displaced in the length direction of the rod as a ring shape into which the cylindrical guide of the rod is loosely inserted. As a result, the rod is moved most stably.
[0018]
The actuator that displaces the permanent magnet must open and close the valve plate with good responsiveness by turning on and off the direct current flowing in the solenoid coil of the electromagnetic actuator consisting of a solenoid coil, a rod-shaped movable core (ferromagnetic material), and a return coil spring. Therefore, it is preferably used. Of course, the actuator may be a pneumatic or hydraulic type other than the electromagnetic type, or may be a mechanical actuator that displaces a permanent magnet by a cam mechanism, and the type of the actuator is not limited.
[0019]
【Example】
Hereinafter, the reciprocating vacuum pump of the present invention will be specifically described with reference to the drawings.
[0020]
FIG. 12 is a perspective view showing a pump chamber 10 as an example of a bellows pump. FIG. 12A shows a case where the side wall 11 and the side wall 19 are set upright, and FIG. The case where it was made to show. The pump chamber 10 has an approximate dodecahedron, the maximum inner volume is 0.6 L, the inner volume when convolved is 0.03 L, and the compression ratio is 20. An intake port 11a and an exhaust port 11b are formed in the side wall 11 of the pump chamber 10, and an intake valve 20 and an exhaust valve 50 (not shown) are attached to them. Then, the side wall 19 is folded between the fixed side wall 11 and expanded by a drive mechanism (not shown), so that the internal volume of the pump chamber 10 is reduced and enlarged to perform the pump action. The reciprocating vacuum pump of the present invention is usually manufactured so that a plurality of pump chambers 10 as described above are connected in series or in series / parallel to obtain a predetermined exhaust speed and ultimate pressure (degree of vacuum). Is done.
[0021]
FIG. 1 is a cross-sectional view of a portion of the intake valve 20 during intake of the pump chamber 10 (when the bellows is expanded), and FIG. 2 is a similar cross-sectional view during exhaust (when the bellows is reduced). FIG. 3 is a cutaway perspective view of the intake valve 20. As shown in FIGS. 1 and 2, the pump chamber 10 has a fixed side wall plate 11 in which the other side wall plate 19 is expanded and folded around a rotation center 18 by a drive mechanism (not shown). The product is enlarged or reduced. The corner portion 16 close to the turning center 18 bent along with it and the convolution portion 17 facing the corner portion 16 are made of urethane rubber, and the side wall 11 and the side wall 19 are made of an aluminum alloy. The joint is firmly and airtightly bonded with an adhesive. Instead of urethane rubber, fluorine rubber, ethylene / propylene rubber, or ultra-high molecular weight polyethylene may be used, and instead of aluminum alloy, stainless steel, titanium, corrosion-resistant nickel alloy, or high-strength resin (engineering plastics) Also good. The most appropriate material is selected according to the purpose of use.
[0022]
As shown in FIG. 1, the intake valve 20 provided on the side wall 11 of the pump chamber 10 presses the valve plate 40 on the pump chamber 10 side against the valve seat 38 provided facing the pump chamber 10. It is comprised so that it may be separated. That is, a valve plate receiver 34 is provided at the intake port 11a of the side wall 11, and an attachment L-shaped pipe 31 of the intake valve 20 is attached so as to press down the collar 33 thereon. The mounting L-shaped pipe 31 is fixed to the side wall 11 of the pump chamber 10 via an O-ring 32 by a bolt (not shown), and a valve seat 38 is formed on the mounting L-shaped pipe 31. 4 is an enlarged view showing the valve plate receiver 34. FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view in the [B]-[B] line direction in A of FIG. That is, the valve plate receiver 34 is formed in a substantially cylindrical shape, a stopper 34a of the valve plate 40 is provided on the upper surface, a support portion 34b of the coil spring 36 is provided on the lower surface, and the air passage 35 is formed in the center. ing.
[0023]
FIG. 5 is a plan view of the valve plate 40. Four protrusions 41 are formed on the outer periphery of the valve plate 40, and an O-ring 42 is fitted on the upper surface of the valve plate 40 with one side exposed. ing. The four spaces sandwiched between the four protrusions 41 serve as ventilation paths 45 when the valve plate 40 is opened. The valve plate 40 is made of polycarbonate, and the weight of the valve plate 40 including the protrusion 41 is about 6 × 10.^-FourIt is extremely lightweight with kg. In addition, a coil spring 36 is interposed between the valve plate 40 and the support portion 34b of the valve plate receiver 34 without being locked at both ends. As shown in FIG. The coil spring 36 is biased and pressed against the valve seat 38 to close the intake port 11a. The pressing force of the coil spring 36 is (3-5) × 10.^-2N.
Further, a rod 22 independent of the valve plate 40 is provided above the valve plate 40, and this rod 22 is lowered against the bias by the coil spring 36 as shown in FIG. Is separated from the valve seat 38 and pushed down until it comes into contact with the stopper 34a of the valve plate receiver 34 to open the intake port 11a. The movement of each element at these times will be described later.
[0024]
The rod 22 is made of polycarbonate and is lightweight. The upper half 22a has a large diameter and is inserted into a deep-drawn cylindrical guide 23 integrated with the mounting L-shaped tube 31. A soft iron piece 21 made of a ferromagnetic material is joined to the upper end surface of 22 and a cross leg 22c is provided at the lower end portion. The upper half 22a of the soft iron piece 21 and the rod 22 is formed with two ventilation grooves 22t that allow the upper and lower portions to communicate with each other. Further, an annular disk 25 holding an annular permanent magnet 24 magnetically coupled to the soft iron piece 21 of the rod 22 is loosely fitted on the outer peripheral surface of the cylindrical guide 23 protruding from the mounting L-shaped pipe 31. 25 is moved up and down by the arm 27 together with the permanent magnet 24 to move the rod 22 up and down. The arm 27 is moved up and down by an electromagnetic actuator 30 as shown in FIG. That is, the electromagnetic actuator 30 is provided with a solenoid coil 28 and a rod-shaped movable iron core 29 in its casing 30c, and the arm 27 is fixed to the upper end portion of the rod-shaped movable iron core 29 by a cross hole screw 29b. A return spring 26 is interposed between the upper surface of the casing 30 c and the arm 27 around the upper end of the rod-shaped movable iron core 29 and the cross hole screw 29 b.
[0025]
When the switch for passing a direct current through the solenoid coil 29 is turned on, the rod-shaped movable iron core 28 is pulled down together with the arm 27 and the permanent magnet 24 against the return spring 26, and as shown in FIG. The intake valve 20 is opened when the rod 22 is lowered together with the soft iron piece 21 magnetically coupled to push down the valve plate 40. Further, when the switch is turned off, in FIG. 3, the return spring 26 works to push up the arm 27 and the permanent magnet 24 to raise the rod 22 together with the soft iron piece 21. Therefore, as shown in FIG. 40 is pushed up, and the intake valve 20 is closed. Such opening and closing of the intake valve 20 is performed in synchronization with the expansion and contraction of the internal volume of the pump chamber 10.
[0026]
  6 is a partially enlarged cross-sectional view showing the expansion and contraction of the coil spring 36 and the raising and lowering of the rod 22 in accordance with the opening and closing of the valve plate 40 shown in FIGS. 1 and 2, and FIG. 6A corresponds to FIG. Of the intake valve 20OpenFIG. 6B shows the state of the intake valve 20 corresponding to FIG.CloseIndicates the state. That is, as shown in FIG. 6A, during intake when the internal volume of the pump chamber 10 is expanded, the valve plate 40 is pushed down by the rod 22 and separated from the valve seat 38, the intake valve 20 is opened, and the gas is attached. It flows into the pump chamber 10 from the L-shaped pipe 31 through the vent passage 45 on the outer peripheral side of the valve plate 40 and the vent passage 35 of the valve plate receiver 34. Further, as shown in FIG. 6B, at the time of exhausting when the internal volume of the pump chamber 10 is reduced, the rod 22 is lifted away from the valve plate 40, and the valve plate 40 is moved by the coil spring 36 via the O-ring 42. The intake valve 20 is closed by being pressed by the valve seat 38 and the backflow of gas from the pump chamber 10 to the mounting L-shaped pipe 31 is prevented. The opening and closing of the valve plate 40 is performed mainly by the pressure difference or the gas flow caused by the pressure difference when the pressure difference between both sides of the valve plate 40 is large. When the pressure difference is small, the valve by the pressure difference is used. This is performed by causing a rectangular wave direct current to flow through the solenoid coil 28 of the actuator 30 in synchronization with the expansion and contraction of the internal volume of the pump chamber 10 so as to move in the same direction as the movement direction of the plate 40.
[0027]
That is, atmospheric pressure (≈1 × 10^Five In the pressure range from Pa) to several hundred Pa, the valve plate 40 is lightweight and the pressing force of the coil spring 36 is small, so that the valve plate 40 is easily opened and closed by the pressure difference generated on both sides of the valve plate 40. For example, the area of the portion surrounded by the O-ring 42 fitted in the valve plate 40 is Sm.² Assuming that the pressure difference between both sides of the valve plate 40 is ΔpPa, the force F shown in (Equation 1) is exerted on the valve plate 40.₁ N is added.
F₁   = Δp · S (Formula 1)
In a normal reciprocating dry pump, S is (1-3) × 10.^-Fourm² △ p is set to 10^Three At the time of Pa, the valve plate 40 has (1-3) × 10^-1N force acts. On the other hand, the pressing force of the valve plate 40 by the coil spring 36 is (3-5) × 10.^-2Since N, the above Δp is 10^Three It is 1/5 to 1/10 of the force acting on the valve plate 40 at Pa. From this, it will be understood that the valve plate 40 is easily opened and closed by the pressure difference between the two sides when it is within the pressure range from atmospheric pressure to several hundred Pa.
[0028]
On the other hand, at a pressure of several hundred Pa or less, the opening and closing of the valve plate 40 due to the pressure difference between both sides of the valve plate 40 cannot be expected, and the valve plate 40 is opened and closed by the electromagnetic force generated when a direct current is passed through the solenoid coil 28 described above. When the pump chamber 10 is evacuated, as shown in FIG. 6B, the rod 22 is raised, the valve plate 40 is urged by the coil spring 36 and pressed against the valve seat 38 via the O-ring 42, and the intake valve 20 is closed. It is said. At this time, the coil spring 36 is in an extended state, and the valve plate 45 and the cross leg 22c at the lower end of the rod 22 are separated from each other. That is, the coil spring 36 biases only the valve plate 40 and presses it against the valve seat 38.
[0029]
During intake of the pump chamber 10, as described above, the switch of the direct current flowing through the solenoid coil 28 of the actuator 30 shown in FIG. 3 is turned on, and the rod-shaped movable iron core 29 is drawn in, and is permanently passed through the arm 27. Since the magnet 24 is lowered, as shown in FIG. 6A, the rod 22 is lowered together with the soft iron piece 21 magnetically coupled to the permanent magnet 24, and the valve plate 40 has a cross leg 22c at the lower end of the rod 22. Therefore, it is lowered until it abuts against the stopper 34 b of the valve plate receiver 34 against the urging by the coil spring 36. At this time, the coil spring 36 is in a compressed state, and the valve plate 40 and the cross leg 22c at the lower end of the rod 22 come into contact with each other. The actuator 30 of this embodiment generates a force of 1 to 2N when a direct current of 0.2 A is passed at a voltage of 24V. When the valve plate 40 is opened, the rod-shaped movable iron core 29 is raised by turning off the direct current switch of the solenoid coil 28.
[0030]
  FIG. 11 shows S = 3 × 10^-4m²Is a diagram showing the pressure difference Δp on both sides of the valve plate 40 as the horizontal axis and the force F acting on the valve plate 40 as the vertical axis. As shown in FIG. 11, the valve plate 40 has a pressing force by the coil spring 36 and a force generated by a pressure difference Δp on both sides of the valve plate 40 and a force by the electromagnetic actuator 30. Act as indicated by broken lines. Accordingly, a force as indicated by a solid line acts on the valve plate 40, and the pressure difference Δp is 10⁵In the entire region from Pa to 1 Pa, the valve plate 40 is opened and closed with a force sufficiently larger than the pressing force of the coil spring 36. That is, the valve plate 40 has a pressure difference Δp of 10³When it is larger than Pa (high pressure side), it is opened and closed by a force mainly caused by the pressure difference, and the pressure difference Δp is 10³When it is smaller than Pa and is not opened or closed due to a pressure difference (low pressure side), mainly due to the electromagnetic force of the actuator 30OpenIs done. The permanent magnet 24 moved up and down by the rod-shaped movable iron core 29 of the actuator 30 is in the form of a cylinder with the soft iron piece 21 of the rod 22.guideAlthough it is magnetically coupled across the 23 vacuum walls and not mechanically coupled, the soft iron piece 21 moves up and down following the permanent magnet 24 with almost no play.The pressure difference Δp on both sides of the valve plate 40 is 5 × 10 ³ When a force at Pa, that is, a force greater than 1.5 N is applied, the rod 22 moves away from the valve body 40.
[0031]
7 is a cross-sectional view of the exhaust valve 50 at the time of intake of the pump chamber 10 (when the bellows is expanded), and FIG. 8 is a similar cross-sectional view at the time of exhaust (when the bellows is reduced). FIG. 9 is a cutaway perspective view of the exhaust valve 50. When viewed from the pump chamber 10 side, the exhaust valve 50 has a positional relationship between the valve body 70 and the valve seat 68 opposite to that of the intake valve 20, and there are some differences based on that, but basically It is constituted similarly and each component is made of the same material. That is, the valve seat 68 is formed on the outer surface side of the side wall 11, and the valve plate 70 is pressed and separated on the outside of the valve seat 68. As shown in FIG. 7, a valve plate receiver 64 similar to the valve plate receiver 34 shown in FIG. 4 is provided with a collar 63 interposed between the exhaust port 11 b of the pump chamber 10. The mounting L-shaped tube 61 presses the collar 63 and is fixed to the side wall 11 of the pump chamber 10 by a bolt (not shown) via a 0-ring 62.
[0032]
The valve plate 70 of the exhaust valve 50 is basically the same as the valve plate 40 shown in FIG. 5 but needs to be lifted when the valve plate 70 is opened. Are connected so that they are not. That is, referring to FIGS. 7 and 8 or A and B of FIG. 10 described later, a hook-like connecting portion 73 for loosely inserting the lower end portion of the rod 52 is formed on the upper surface of the valve plate 70. A stopper 52 c is attached to the lower end of the rod 52 inserted into the portion 73. The rest of the configuration is the same as the valve plate 40 of the intake valve 20. A coil spring 66 is interposed freely between the valve plate 70 and the support portion 64a of the valve plate receiver 64 without engaging both ends.
[0033]
And the soft iron piece 51 is joined to the front-end | tip part of the rod 52, and it is inserted in the cylindrical guide 53 provided by protruding from the attachment L-shaped pipe 61. An annular disk 55 holding an annular permanent magnet 54 magnetically coupled to the soft iron piece 51 of the rod 52 is loosely fitted on the outer peripheral surface of the cylindrical guide 53, and the solenoid coil 58 shown in FIG. The rod 52 is moved up and down by the actuator 60 composed of the iron core 59 as in the case of the intake valve 20.
[0034]
10 is a partially enlarged sectional view showing the expansion and contraction of the coil spring 66 accompanying the opening and closing of the valve plate 70 shown in FIGS. 7 and 8 and the raising and lowering of the rod 52 in an enlarged manner, and FIG. FIG. 10B shows a closed state of the exhaust valve 50 corresponding to FIG. That is, as shown in FIG. 10A, at the time of intake in which the internal volume of the pump chamber 10 is expanded, the rod 52 is lowered and play is generated in the hook-shaped connecting portion 73, and the valve plate 70 is extended by a coil spring. Since the exhaust valve 50 is closed by being pressed against the valve seat 68 by 66, the backflow of gas from the mounting L-shaped pipe 61 into the pump chamber 10 is prevented.
[0035]
Further, as shown in FIG. 10B, the rod 52 is raised during exhausting when the internal volume of the pump chamber 10 is reduced, and the stopper 52c of the rod 52 pulls up the hook-like connecting portion 73 of the valve plate 70. The plate 70 is separated from the valve seat 68 against the biasing force of the coil spring 66, the exhaust valve 50 is opened, and the gas in the pump chamber 10 is attached from the outer peripheral side of the valve plate 70 through the vent passage of the valve plate receiver 64. Exhaust into the L-shaped tube 61.
The opening and closing of the valve plate 70 is mainly performed by the pressure difference when the pressure difference between both sides of the valve plate 70 is equal to or higher than the limit pressure of about several hundred Pa, and the pressure difference between both sides of the valve plate 70 is less than the limit pressure. At this time, what is performed by the actuator 60 is the same as that of the intake valve 20.
[0036]
The intake valve 20 and the exhaust valve 50 have a gas pressure of 10 as described above.^Five Although it can be opened and closed in a wide pressure range from Pa to 1 Pa, since the compression ratio of the pump chamber 10 is 20, as described above, when the pump chamber 10 is a single reciprocating vacuum pump, it is atmospheric pressure. (≒ 1 × 10^Five The ultimate pressure from Pa) is 5 × 10^Three It becomes about Pa. However, a reciprocating vacuum pump in which four such pump chambers 10 are connected in series, that is, an adjacent upstream pump chamber 10.₁ The exhaust port of the pump chamber 10 on the downstream side₂ A vacuum pump connected to the intake port of one of the pump chambers 10₁ Is in the expansion period of the internal volume, the other pump chamber 10₂ By operating so that the internal volume is in the contraction period, the ultimate pressure becomes about 1 Pa, and the oil rotary pump can be sufficiently replaced.
[0037]
The reciprocating vacuum pump according to the embodiment of the present invention is configured and operates as described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention. is there.
[0039]
In the present embodiment, the reciprocating vacuum pump in which the pump chambers are connected in series is exemplified. However, the pump chamber connected in parallel and the pump chamber connected in series and in parallel are also reciprocating. Included in vacuum pump.
In the present embodiment, the switch of the direct current flowing through the solenoid coil of the actuator that raises and lowers the rod is turned on and off in synchronization with the expansion and reduction of the internal volume of the pump chamber. The expansion or reduction of the internal volume of the pump chamber is detected by a photoelectric sensor or a pressure sensor, and a control circuit having a switch for turning on / off a direct current in synchronization with the detection is provided.
[0040]
【The invention's effect】
The reciprocating vacuum pump of the present invention is implemented in the form as described above, and has the following effects.
[0041]
  The present inventionAccording to the above, even when the pressure difference between both sides of the valve plate is smaller than the limit pressure of about several hundred Pa, the intake valve and the exhaust valve that are surely opened and closed in synchronization with the expansion and reduction of the internal volume of the pump chamber are provided. 10 pump rooms⁵Vacuum exhaust is possible in the pressure region from Pa to 1 Pa, and the operation of the rod of the valve plate of the intake valve and exhaust valve is performed by the actuator on the atmosphere side, so that the actuator does not become exhaust resistance, By connecting these pump chambers in series, it is possible to obtain a dry type vacuum pump with an ultimate pressure of about 1 Pa that can be replaced with an oil rotary pump at a low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an intake valve portion during intake of a pump chamber of a bellows pump.
FIG. 2 is a cross-sectional view of an intake valve portion during exhaust of a pump chamber.
FIG. 3 is a cutaway perspective view of an intake valve.
4A and 4B are views showing a valve plate receiver, in which A is a plan view and B is a cross-sectional view taken along line [B]-[B] in A. FIG.
FIG. 5 is a plan view of a valve plate.
FIGS. 6A and 6B are partial enlarged cross-sectional views of the intake valve, where A is during intake and B is during exhaust.
FIG. 7 is a cross-sectional view of an exhaust valve portion during intake of the pump chamber.
FIG. 8 is a cross-sectional view of an exhaust valve portion during exhaust of the pump chamber.
FIG. 9 is a cutaway perspective view of an exhaust valve.
FIGS. 10A and 10B are partial enlarged cross-sectional views of an exhaust valve, in which A is during intake and B is during exhaust.
FIG. 11 is a diagram showing the relationship between the pressure difference on both sides of the valve plate and the force acting on the valve plate.
FIGS. 12A and 12B are perspective views showing an example of a pump chamber of a bellows pump. FIG. 12A shows a case where the side wall is set up and B shows a case where the posture of A is turned over.
FIG. 13 is a cross-sectional view of an intake valve portion of a pump chamber in a conventional bellows pump.
[Explanation of symbols]
10 Pump room
11 Side wall
19 Side wall
20 Intake valve
21 Soft iron pieces
22 Rod
23 Cylindrical guide
24 Permanent magnet
26 Return spring
27 arm
28 Solenoid coil
29 Rod-shaped movable iron core
30 Actuator
31 Mounting L-shaped tube
34 Valve plate holder
36 Coil spring
38 Valve seat
40 Valve plate
50 Exhaust valve
51 soft iron pieces
52 Rod
53 Cylindrical guide
54 Permanent magnet
56 Return spring
57 arm
58 Solenoid coil
59 Rod-shaped movable core
60 Actuator
61 Mounting L-shaped tube
64 Valve plate holder
66 Coil spring
68 Valve seat
70 Valve plate
73 bowl-shaped connecting part

Claims (3)

A first side wall formed with an air inlet and an air outlet; a second side wall that is rotated with respect to the first side wall; and a convolution that faces the center of rotation of the second side wall. And a pump chamber whose internal volume is expanded or reduced by expansion or convolution of the convolution part accompanying the rotation of the second side wall,
A first valve seat formed at the intake port, a first valve plate that can be separated from and seated on the first valve seat, and urging the first valve plate toward the first valve seat A first spring, a first rod having a ferromagnetic material, a first permanent magnet magnetically coupled to the ferromagnetic material, and the first permanent magnet in the length direction of the first rod A first actuator that moves the first rod in the length direction by displacing the first rod, and the first actuator causes the first actuator to be inhaled when the internal volume of the pump chamber is expanded. An intake valve mechanism capable of separating the first valve plate from the first valve seat against the bias of the first spring by moving the rod in the length direction;
A second valve seat formed at the exhaust port, a second valve plate that can be separated from and seated on the second valve seat, and the second valve plate are urged toward the second valve seat. A second spring, a second rod having a ferromagnetic material, a second permanent magnet magnetically coupled to the ferromagnetic material, and the second permanent magnet in the length direction of the second rod. A second actuator that moves the second rod in the length direction by displacing the second rod, and the second actuator causes the second actuator to be exhausted when the internal volume of the pump chamber is reduced. An exhaust valve mechanism capable of moving the rod in the length direction to separate the second valve plate from the second valve seat against the bias of the second spring;
A reciprocating vacuum pump comprising: The reciprocating vacuum pump according to claim 1,
The first and second actuators are electromagnetic actuators including a solenoid coil, a rod-shaped movable iron core (ferromagnetic material), and a return coil spring that urges the rod-shaped movable iron core, and has an internal volume of the pump chamber. A DC current flowing through the solenoid coil is turned on / off in synchronization with expansion and contraction to move the rod-shaped movable iron core in the length direction of the first and second rods against the bias of the return coil spring . Reciprocating vacuum pump. The reciprocating vacuum pump according to claim 1 or 2,
A plurality of the pump chambers are connected in series, and exhaust from the exhaust port of the adjacent upstream pump chamber is sucked into the intake port of the downstream pump chamber, and the upstream pump chamber A reciprocating vacuum pump in which the pump chamber on the downstream side is operated in the opposite phase so that the downstream pump chamber is in the expansion period of the internal volume when the internal volume is in the contraction period of the internal volume.

Images