JP2007291940A - Vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump reduced in exhaust noise and drive power. <P>SOLUTION: This vacuum pump comprises a cylinder having suction and exhaust valves, a piston so structured that is reciprocatingly moved in the cylinder, a connecting rod for reciprocatingly moving the piston, a crank for converting the rotating motion of a motor into the vertical motion, and a housing for covering the crank portion from the lower side of the cylinder. The housing has a housing suction port for introducing exhaust gases thereinto, a housing exhaust port for discharging exhaust gases from the housing to the outside, and a conduit for guiding exhaust gases to the housing suction port. A restriction valve is installed on the downstream side of the housing exhaust port. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum pump. More specifically, the present invention relates to a rocking piston type dry vacuum pump, and relates to a pump with improved power reduction and noise reduction effect.

  As shown in FIG. 1, the oscillating piston vacuum pump 101 includes a cylinder 102, a piston 103, and a connecting rod 104. The rotary motion of a motor 106 is converted into a vertical motion via a crank 105, and a head plate at the top of the cylinder is converted. This is a pump that compresses or depressurizes a fluid via an intake valve 108 and an exhaust valve 109 of 107. A piston cup 110 made of resin is provided on the upper portion of the piston 103 to seal with the cylinder 102. A head cover 111 is provided at the upper part of the cylinder, and an intake port 112 and an exhaust port 113 are formed. When the exhaust from the vacuum pump is discharged into the atmosphere as it is, exhaust noise is generated. In order to reduce this, the exhaust pipe is equipped with various silencers 114 to reduce noise.

  As another method for reducing the noise, as shown in FIG. 2, the vacuum exhaust discharged from the exhaust port 213 is once taken into the housing 216 from the housing intake port 217 via the conduit 215, and the pressure fluctuation due to the exhaust pulsation There is also known a method of releasing the air from the housing exhaust port 218 after relaxing the above.

The housing 216 is a storage chamber that covers the connecting portion 204 of the lower cylinder and the driving portion of the piston 203 including the crank 205, and prevents the intrusion of ash dust into the cylinder portion and the release of ash dust from equipment such as oil and wear powder to the outside. Yes. The housing 216 seals the device drive unit to prevent the transmission of drive sound and to reduce noise.
JP 2003-328938 A

  The oscillating piston type vacuum pump performs the pump function by sucking and exhausting the air in the cylinder by the vertical movement of the piston, but when the housing part including the lower part of the piston is sealed, the piston As a result of the vertical movement, pressure fluctuation occurs in the housing. When exhaust is directly discharged into the atmosphere, the rising pressure in the housing that accompanies the lowering of the piston can be reused to push up the piston, leading to a reduction in piston driving power. However, in order to reduce noise, it is necessary to provide a silencer such as a silencer.

  When noise is reduced due to pulsation relaxation by introducing exhaust into the housing, the vacuum pump itself is always driven. As the displacement of the exhaust gas introduced into the housing changes, the housing internal pressure always changes.

  When evacuating the vacuum pump, the piston in the cylinder is pushed up, and the exhaust from the cylinder is returned to the housing, so there is no pressure fluctuation in the housing, but during intake, the piston in the cylinder is pushed down, and the volume of the piston is reduced. As the air is inhaled, the internal pressure of the housing increases. The housing exhaust port is exhausted by the pressure increase, but the piston drive is faster, leading to an increase in internal pressure, resulting in an increase in power. Increasing the exhaust port of the housing solves this problem, but not only does the effect of reducing exhaust noise not be obtained, but also noise from the crank etc. housed inside the housing leaks to the outside. The noise reduction effect is reduced.

  When the degree of vacuum increases, the intake / exhaust amount becomes smaller than the piston drive volume. As a result, at the time of exhaust, the volume due to the piston being pushed up becomes larger than the amount of exhaust air flowing into the housing, and a reverse flow phenomenon of air from the housing exhaust port into the housing occurs. Such intake / exhaust at the housing exhaust port not only becomes a new noise generation source, but also causes a problem that pump power increases due to pressure loss.

The present inventor has found the following vacuum pump as means for solving the above problems.
That is, the present invention relates to a cylinder having intake and exhaust valves, a piston configured to reciprocate within the cylinder, a connecting rod that reciprocates the piston, and a crank that converts the rotational motion of the motor into vertical motion. A vacuum pump having a housing that covers a crank portion from a lower part of the cylinder, a housing intake port for introducing exhaust gas into the housing, a housing exhaust port for discharging exhaust gas from the housing, and an exhaust gas to the housing intake port And a vacuum pump having a throttle valve downstream of the housing exhaust port.

  Further, the present invention is characterized in that the throttle valve is a valve that controls the intake air amount of the vacuum pump and the exhaust air amount from the housing in the same manner, and particularly includes a detecting means for detecting the rotation speed of the crank. A vacuum pump comprising control means for controlling the opening and closing of the throttle valve based on the detection result, a flow meter for measuring the flow rate of the intake air sucked into the cylinder, and the flow rate value of the flow meter The present invention provides a vacuum pump comprising control means for controlling opening and closing of the throttle valve based on the above.

  Further, the present invention provides a vacuum pump that performs intake and exhaust by reciprocating a piston in a cylinder, the step of introducing the exhaust from the cylinder into a housing that houses a lower part of the cylinder and a drive unit of the piston, A vacuum pump operation control method comprising a step of discharging exhaust gas to the outside and a step of controlling the discharge amount so that the discharge amount of the exhaust gas becomes equal to the intake air amount to the cylinder.

  In the vacuum pump of the present invention, a throttle valve is disposed at the exhaust port of the housing so that the intake air volume of the vacuum pump is equal to the exhaust air volume from the housing, so that only the exhaust of the vacuum pump is discharged from the housing exhaust port. Since the outside air does not flow into the housing, the pressure loss in the housing is eliminated when the vacuum pump is exhausted. As a result, the pump power is reduced. Further, since the exhaust pressure of the vacuum pump is a force that pushes up the piston, the power becomes the same level as when the housing is sealed, and at the same time, the exhaust noise can be reduced.

The example of the embodiment of the vacuum pump of the present invention is explained using a drawing.
FIG. 3 is a schematic cross-sectional view of a reciprocating vacuum air pump 301 having an aluminum cylinder 302 and a piston 303 that swings inside the cylinder. The rotary motion of the motor 306 is converted into a reciprocating motion by a crank 305, and a connecting rod 304 is converted. The piston 303 is reciprocated with this. The fluid is depressurized via an intake valve 308 and an exhaust valve 309 provided on a head plate 307 at the upper part of the cylinder 302. A piston cup 310 made of polytetrafluoroethylene resin is provided on the upper portion of the piston 303 to seal with the cylinder 302. A head cover 311 is provided at the upper part of the cylinder, and an intake port 312 and an exhaust port 313 are formed. The vacuum exhaust exhausted from the exhaust port 313 is once taken into the housing 316 from the housing intake port 317 via the conduit 315, and is released to the outside from the housing exhaust port 318 after reducing pressure fluctuation due to exhaust pulsation. The housing 316 is a storage chamber that covers the connecting rod 304 at the bottom of the cylinder and the drive portion of the piston 303 including the crank 305. Intrusion of ash dust into the cylinder portion and release of ash dust from equipment such as oil and wear powder to the outside Is preventing.

  A throttle valve 322 is provided downstream of the housing exhaust port 318. The throttle valve 322 is opened and closed by measuring the amount of suction into the vacuum pump with the flow meter 321, and based on the detection result, the amount of suction from the suction port 312 and the amount of exhaust from the housing exhaust port 318 are the same by the controller 320. Control to become. The relationship between the opening and closing of the throttle valve 322 and the exhaust amount when the motor 306 is driven at a predetermined number of revolutions is stored, and the opening and closing of the throttle valve 322 is automatically controlled based on the detection value of the flow meter 321. It is also possible to adopt a pressure gauge instead of the flow meter 321, and to control the opening of the throttle valve 322 from the relationship between the pressure value and the flow value stored in advance.

  In FIG. 4, the configuration of the vacuum pump is the same as that of the apparatus of FIG. 3, and a flow meter 423 is further provided downstream of the housing exhaust port 318, and the intake air amount to the intake port 412 and the exhaust amount from the housing exhaust port 318 The detected values of the flow meter 421 and the flow meter 423 are taken into the controller 420 so that they are the same, and the opening / closing of the throttle valve 422 is automatically controlled so that they are the same. This can be applied when both the vacuum pressure value and the rotation speed of the motor 406 are variable.

  When the vacuum pump is used so that the rotation speed is variable in order to adjust the vacuum pressure to a constant pressure, the relationship between the intake amount and the rotation speed of the motor 506 is measured and stored in advance as shown in FIG. The controller 520 automatically controls the opening / closing of the throttle valve 522 in accordance with the motor speed so that the intake air amount and the exhaust air amount become the same.

  When the vacuum pump is used at a constant rotational speed and a constant vacuum pressure, as shown in FIG. 6, the intake amount of the vacuum pump is measured in advance, and the fixed throttle is set so that the exhaust amount is the same as the intake amount. Valve 622 is mounted downstream of housing exhaust 618.

  FIG. 7 shows the power reduction effect of the embodiment of the vacuum pump of the present invention. Using the vacuum pump having the configuration shown in FIG. 3, the throttle valve 322 was manually controlled, and it was experimentally confirmed that the power consumption changed depending on the exhaust pressure at the housing exhaust port 318. Since the vacuum pump used in the transition region until reaching the vacuum is assumed, the vacuum chamber inflow valve 325 was adjusted so that the pressure in the vacuum chamber 324 was −45 kPa (420 Torr). The air volume at the housing exhaust port 318 is the sum of the gas exhausted from the housing 316 and the inflowing gas. When this air volume and the air volume at the intake port 312 are equal (2), the power consumption is minimum. Is shown. The air volume is expressed as a mass flow rate based on 20 ° C. and 1 atm. When the intake / exhaust air volume at the housing exhaust port 318 is larger than the intake air volume at the intake port 312 (1), the power consumption starts to increase due to the effect of pressure loss at the housing exhaust port 318. Further, when the intake / exhaust air volume at the housing exhaust port 318 is smaller than the intake air volume at the intake port 312 (3), the power required to push up the piston 303 is increased, and thus the power consumption is increased. That is, the power consumption can be reduced by adjusting the throttle valve 322 so that the intake air volume at the intake port 312 and the intake / exhaust air volume at the housing exhaust port 318 become equal.

The example of the embodiment of the conventional vacuum pump. The example of the embodiment of the conventional vacuum pump. The embodiment example of the vacuum pump of this invention. The embodiment example of the vacuum pump of this invention. The embodiment example of the vacuum pump of this invention. The embodiment example of the vacuum pump of this invention. The power reduction effect of the vacuum pump of the present invention.

Explanation of symbols

101,201,301,401,501,601. Vacuum pump
102,202,302,402,502,602. Cylinder
103,203,303,403,503,603. Piston
104,204,304,404,504,604. Connecting rod
105,205,305,405,505,605. Crank
106,206,306,406,506,606. Motor
107,207,307,407,507,607. Head plate
108,208,308,408,508,608. Intake valve
109,209,309,409,509,609. Exhaust valve
110,210,310,410,510,610. Piston cup
111,211,311,411,511,611. Head cover
112,212,312,412,512,612. Intake port
113,213,313,413,513,613. Exhaust port
114. Silencer
215,315,415,515,615. Conduit
116,216,316,416,516,616. Housing
217,317,417,517,617. Housing inlet
218,318,418,518,618. Housing exhaust
320,420,520. Controller
321,421. Flowmeter
322,422,522,622. Throttle valve
423. Flowmeter
124,224,324,424,524,624. Vacuum chamber
325. Vacuum chamber inlet valve

Claims (5)

  A cylinder having valves for intake and exhaust, a piston configured to reciprocate in the cylinder, a connecting rod for reciprocating the piston, a crank for converting the rotational movement of the motor into a vertical movement, and a lower part of the cylinder A vacuum pump having a housing that covers a crank portion, the housing including a housing intake port for introducing exhaust gas, a housing exhaust port for discharging exhaust gas from the housing, and a conduit for guiding the exhaust to the housing intake port A vacuum pump provided with a throttle valve capable of controlling the air volume downstream of the housing exhaust port.   2. The vacuum pump according to claim 1, further comprising a detection unit that detects the number of rotations of the crank, and a control unit that controls opening and closing of the throttle valve based on a detection result.   2. A vacuum pump according to claim 1, further comprising a flow meter for measuring a flow rate of the intake air sucked into the cylinder, and control means for controlling opening and closing of the throttle valve based on a flow value of the flow meter. .   A flow meter for measuring a flow rate of intake air sucked into the cylinder and an exhaust air flow rate from the housing is provided, and control means for controlling opening and closing of the throttle valve based on flow rate values of both flow meters is provided. The vacuum pump according to claim 1.   In a vacuum pump that performs intake and exhaust by reciprocating a piston in a cylinder, introducing the exhaust from the cylinder into a housing that houses the lower part of the cylinder and the drive unit of the piston, and releasing the exhaust from the housing to the outside A method for controlling the operation of the vacuum pump, comprising the step of controlling the discharge amount so that the discharge amount of the exhaust gas is equal to the intake amount to the cylinder.

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