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WO2006097054A1 - Two-stage piston vacuum pump - Google Patents

Two-stage piston vacuum pump Download PDF

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Publication number
WO2006097054A1
WO2006097054A1 PCT/CZ2006/000012 CZ2006000012W WO2006097054A1 WO 2006097054 A1 WO2006097054 A1 WO 2006097054A1 CZ 2006000012 W CZ2006000012 W CZ 2006000012W WO 2006097054 A1 WO2006097054 A1 WO 2006097054A1
Authority
WO
WIPO (PCT)
Prior art keywords
stage
piston
vacuum pump
exhaust
exhaust valve
Prior art date
Application number
PCT/CZ2006/000012
Other languages
French (fr)
Inventor
Jiri Jan
Original Assignee
Jiri Jan
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jiri Jan filed Critical Jiri Jan
Publication of WO2006097054A1 publication Critical patent/WO2006097054A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B25/00—Multi-stage pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B25/00—Multi-stage pumps
    • F04B25/005—Multi-stage pumps with two cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/14—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/14—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high vacuum
    • F04B37/16—Means for nullifying unswept space

Definitions

  • the inventions relates to two-stage piston vacuum pumps
  • the rotary oil vacuum pump are largely used for their low limit pressure in comparison with the dry piston vacuum pumps.
  • the rotary oil vacuum pump are less ecologically friendly since they may adversely affect by the oil products released from the pumps the environment including the exhausted vacuum space as such.
  • a first way how to overcome this problem is to reduce the dead space to minimum by a suitable design.
  • the dead space is represented by a volume of the closed space in the pump cylinder above the piston when the piston in its upper dead point.
  • a second way is directed to the effort to facilitate to the maximum the opening of the exhaust valve and thus to reduce the pressure which is required for opening the valve. Consequently, the medium in the dead space may be maintained under a lower pressure and a reduced amount of the medium pumped is delivered back into the vacuum exhaust space.
  • the pressure required for the opening the exhaust valve may be reduced by extending the valve size.
  • the size of the valve is even equal to the size of the piston.
  • the weigh of the valve and the mechanical stiffness of the valve spring may be reduced. Nevertheless, such efforts are limited by a strict requirement for the valve to perform reliable closing function at all pressure stages. Also, if the vacuum pump operates at a limit pressure the pressure in its dead space, when the piston is in its upper dead point, is always higher than the pressure beyond the exhaust valve since the other side of the exhaust valve is exposed not only to the pressure of the pumped medium but also to the force of the spring.
  • An object of the invention is to reduce the limit pressure with the environment friendly, dry, oil-free vacuum pumps and thus to extend their service range including the possibility to replace to some extent the rotary oil vacuum pumps.
  • a two-stage piston vacuum pump comprising a crankcase, a crankshaft, an electric motor, a first stage piston including a connecting rod, a first-stage cylinder including a suction channel, a first-stage cylinder head provided with a chamber comprising an exhaust valve and an exhaust channel, a second-stage piston including a connecting rod, a second-stage cylinder including a suction channel, a second- stage cylinder head provided with a chamber comprising an exhaust valve and an exhaust channel, whereby the exhaust channel of the first-stage head is connected to the suction channel of the second-stage cylinder.
  • a dead space defined by the inner wall of the first-stage cylinder, the first-stage head including the exhaust valve and the first-stage piston in the position of the upper dead point is connected with the chamber of the first-stage valve through a suction channel and over an opening mechanism.
  • the vacuum pump is able to operate at a lower pressure in accordance with the main object of the invention.
  • the opening mechanism is a revolving valve the rotation whereof is derived from the electric motor shaft advantageously from its end opposite the crankcase.
  • the advantage of the revolving valve the rotation of which is derived from the electric motor shaft is that the time of its opening and subsequent closing is determined by its mechanical coupling with the position of the piston and is not affected by the speed variations of the electric motor speed.
  • the opening mechanism including the suction channel is advantageous installed only at the stages near the vacuum exhaust space while the last stage, at which the sucked medium is urged out of the vacuum pump is of a conventional design i.e. its is provided with an exhaust valve only.
  • Fig. I. - is a partial sectional view of the vacuum pump according to the invention.
  • Fig. 1 illustrates a two-stage vacuum pump according to the invention in a partial sectional view.
  • the vacuum pump consist of a crankcase 1 including a crankshaft 2, an electric motor 3_, a first-stage piston 4 with a connecting rod 5_, a first-stage cylinder 6 including a suction channel 7, a first-stage head 8 provided with a chamber 9 including an exhaust valve K) and exhaust channel JJ,.
  • the vacuum pump further comprises a second-stage piston 12 with a connecting rod JJ3, a second cylinder 14 including a suction channel 15, a second-stage head 16 provided with a chamber J/7 including an exhaust valve 18 and an exhaust channel 19.
  • the exhaust channel H of the first-stage head 8 is connected to the suction channel 15 of the second-stage cylinder 14.
  • a dead space 20 of the first-stage defined by the first-stage cylinder 6 inner wall, the first- stage head 8 including the exhaust valve JJ) and the first-stage piston 4 in its upper dead point position, is connected through the suction channel 21_ over the opening mechanism 22 to the chamber 9 including the first-stage exhaust valve 10.
  • the opening mechanism 22 consists of a revolving valve 23 the rotation of which is derived from the shaft of the electric motor 3 by means of an indented belt 24.
  • Fig. 1 the first-stage piston is situated in the upper dead point.
  • the opening mechanism 22 is shown in its opened position.
  • the invention is applicable in particular to dry, oil-free piston vacuum pumps and enables the extension of their service range and consequently the replacement to some extent of the ecologically less friendly oil vacuum pumps.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)

Abstract

The invention relates to a piston pump having the first-stage dead space (20) defined by the inner wall of the first-stage cylinder (6), the first-stage head (8) including the exhaust valve (10) and the first-stage piston (4) in the position of the upper dead point connected to a suction channel (21) over an opening mechanism (22) with the chamber (9) of the first-stage exhaust valve (10).

Description

Two-stage piston vacuum pump
Field of the invention
The inventions relates to two-stage piston vacuum pumps
Description of prior art
In the present time the rotary oil vacuum pump are largely used for their low limit pressure in comparison with the dry piston vacuum pumps. On the other hand, the rotary oil vacuum pump are less ecologically friendly since they may adversely affect by the oil products released from the pumps the environment including the exhausted vacuum space as such.
The known dry multiple-stage piston vacuum pumps, although ecologically friendly, are still facing a problem of achieving the lowest possible pressure (the limit pressure) in the vacuum exhaust space.
A first way how to overcome this problem is to reduce the dead space to minimum by a suitable design. The dead space is represented by a volume of the closed space in the pump cylinder above the piston when the piston in its upper dead point. By reducing the dead space the quantity of the pumped medium, which is delivered back into to the vacuum exhaust space on each stroke is limited when the vacuum pump operates under the limit pressure. Nevertheless, the possibility to reduce the dead space is limited by the manufacturing costs since the minimum dead space is conditional on the minimum clearance between the respective parts of the pump.
A second way is directed to the effort to facilitate to the maximum the opening of the exhaust valve and thus to reduce the pressure which is required for opening the valve. Consequently, the medium in the dead space may be maintained under a lower pressure and a reduced amount of the medium pumped is delivered back into the vacuum exhaust space.
The pressure required for the opening the exhaust valve may be reduced by extending the valve size. According to one prior art solution the size of the valve is even equal to the size of the piston. Further, the weigh of the valve and the mechanical stiffness of the valve spring may be reduced. Nevertheless, such efforts are limited by a strict requirement for the valve to perform reliable closing function at all pressure stages. Also, if the vacuum pump operates at a limit pressure the pressure in its dead space, when the piston is in its upper dead point, is always higher than the pressure beyond the exhaust valve since the other side of the exhaust valve is exposed not only to the pressure of the pumped medium but also to the force of the spring.
An object of the invention is to reduce the limit pressure with the environment friendly, dry, oil-free vacuum pumps and thus to extend their service range including the possibility to replace to some extent the rotary oil vacuum pumps.
Summary of the invention
The object of the invention is achieved by a two-stage piston vacuum pump comprising a crankcase, a crankshaft, an electric motor, a first stage piston including a connecting rod, a first-stage cylinder including a suction channel, a first-stage cylinder head provided with a chamber comprising an exhaust valve and an exhaust channel, a second-stage piston including a connecting rod, a second-stage cylinder including a suction channel, a second- stage cylinder head provided with a chamber comprising an exhaust valve and an exhaust channel, whereby the exhaust channel of the first-stage head is connected to the suction channel of the second-stage cylinder. According to the invention, a dead space defined by the inner wall of the first-stage cylinder, the first-stage head including the exhaust valve and the first-stage piston in the position of the upper dead point is connected with the chamber of the first-stage valve through a suction channel and over an opening mechanism.
According to the invention, at the time when the piston reaches its upper dead point the pressure in the dead space is reduced in that the opening mechanism is opened for certain time and the dead space is connected through the suction channel to a space behind the exhaust valve where the pressure is lower. Thus the vacuum pump is able to operate at a lower pressure in accordance with the main object of the invention.
Advantageously, the opening mechanism is a revolving valve the rotation whereof is derived from the electric motor shaft advantageously from its end opposite the crankcase.
The advantage of the revolving valve the rotation of which is derived from the electric motor shaft is that the time of its opening and subsequent closing is determined by its mechanical coupling with the position of the piston and is not affected by the speed variations of the electric motor speed.
With the multiple-stage vacuum pumps, the opening mechanism including the suction channel is advantageous installed only at the stages near the vacuum exhaust space while the last stage, at which the sucked medium is urged out of the vacuum pump is of a conventional design i.e. its is provided with an exhaust valve only.
Brief description of the drawings
The invention is explained in more detail by way of example of its embodiment and the accompanying drawings wherein:
Fig. I. - is a partial sectional view of the vacuum pump according to the invention.
Detailed description of embodiments of the invention
Fig. 1 illustrates a two-stage vacuum pump according to the invention in a partial sectional view. The vacuum pump consist of a crankcase 1 including a crankshaft 2, an electric motor 3_, a first-stage piston 4 with a connecting rod 5_, a first-stage cylinder 6 including a suction channel 7, a first-stage head 8 provided with a chamber 9 including an exhaust valve K) and exhaust channel JJ,. The vacuum pump further comprises a second-stage piston 12 with a connecting rod JJ3, a second cylinder 14 including a suction channel 15, a second-stage head 16 provided with a chamber J/7 including an exhaust valve 18 and an exhaust channel 19. The exhaust channel H of the first-stage head 8 is connected to the suction channel 15 of the second-stage cylinder 14.
A dead space 20 of the first-stage defined by the first-stage cylinder 6 inner wall, the first- stage head 8 including the exhaust valve JJ) and the first-stage piston 4 in its upper dead point position, is connected through the suction channel 21_ over the opening mechanism 22 to the chamber 9 including the first-stage exhaust valve 10.
The opening mechanism 22 consists of a revolving valve 23 the rotation of which is derived from the shaft of the electric motor 3 by means of an indented belt 24. In Fig. 1 the first-stage piston is situated in the upper dead point. The opening mechanism 22 is shown in its opened position. Industrial applicability
The invention is applicable in particular to dry, oil-free piston vacuum pumps and enables the extension of their service range and consequently the replacement to some extent of the ecologically less friendly oil vacuum pumps.
Reference characters
1 - crankcase
2 - crankshaft
3 - electric motor
4 - first-stage piston
5 - connecting rod
6 - first-stage cylinder
7 - suction channel
8 - first-stage head
9 - chamber
10 - exhaust valve
11 - exhaust channel
12 - first-stage piston
13 - connecting rod
14 - second-stage cylinder
15 - suction channel
16 - second-stage head
17 - chamber
18 - exhaust valve
19 - exhaust valve
20 - first-stage dead space
21 - suction valve
22 - opening mechanism
23 - revolving valve
24 - indented belt

Claims

5 CLAIMS
1. A two-stage piston vacuum pump comprising a crankcase (1), a crankshaft (2), an electric motor (3), a first stage piston (4) including a connecting rod (5), a first-stage cylinder (6) including a suction channel (7), a first-stage cylinder head (8) provided with a chamber (9) comprising an exhaust valve (10) and an exhaust channel (11), a second-stage piston (12) including s connecting rod (13), a second-stage cylinder (14) including a suction channel (15), a second-stage cylinder head (16) provided with a chamber (17) comprising an exhaust valve (18) and an exhaust channel (19, whereby the exhaust channel (11) of the first-stage head (8) is connected to the suction channel (15) of the second-stage cylinder (14) characterized in that the first-stage dead space (20) defined by the inner wall of the first-stage cylinder (6), the first-stage head (8) including the exhaust valve (10) and the first-stage piston (4) hi the position of the upper dead point is connected with the chamber (9) of the first-stage exhaust valve (10) through a suction channel (21) and over an opening mechanism (22).
2. A two-stage piston vacuum pump of claim 1 characterized in that the opening mechanism (22) is a revolving valve (23).
3. A two-stage piston vacuum pump of claim 2 characterized in that the rotation of the revolving valve (23) is derived by means of an indented belt (24) from the shaft end of the electric motor (3) situated opposite the shaft end coupled with the crankcase (1).
4. A piston vacuum pump of claim 1 characterized in that it includes three or more stages whereby only certain stages are provided with the opening mechanism (22).
PCT/CZ2006/000012 2005-03-17 2006-03-16 Two-stage piston vacuum pump WO2006097054A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CZPV2005-176 2005-03-17
CZ20050176A CZ2005176A3 (en) 2005-03-17 2005-03-17 Two-stage piston vacuum pump

Publications (1)

Publication Number Publication Date
WO2006097054A1 true WO2006097054A1 (en) 2006-09-21

Family

ID=36588772

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CZ2006/000012 WO2006097054A1 (en) 2005-03-17 2006-03-16 Two-stage piston vacuum pump

Country Status (2)

Country Link
CZ (1) CZ2005176A3 (en)
WO (1) WO2006097054A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE42649C (en) * H. A. HÜLSENBERG in Freiberg i. S Compound air pump
DE72719C (en) * A. A, DITTMAR, H. FALKENHAUSEN und A. L. REINMANN in New-York, V. St. A Air pump with several cylinders and controlled valves, in which the pressure chamber of each previous cylinder is connected to the suction chamber of each subsequent one
DE3112386A1 (en) * 1981-03-28 1982-12-02 Fichtel & Sachs Ag, 8720 Schweinfurt Compressor
US5632605A (en) * 1992-12-21 1997-05-27 Commonwealth Scientific And Industrial Research Organisation Multistage vacuum pump

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE42649C (en) * H. A. HÜLSENBERG in Freiberg i. S Compound air pump
DE72719C (en) * A. A, DITTMAR, H. FALKENHAUSEN und A. L. REINMANN in New-York, V. St. A Air pump with several cylinders and controlled valves, in which the pressure chamber of each previous cylinder is connected to the suction chamber of each subsequent one
DE3112386A1 (en) * 1981-03-28 1982-12-02 Fichtel & Sachs Ag, 8720 Schweinfurt Compressor
US5632605A (en) * 1992-12-21 1997-05-27 Commonwealth Scientific And Industrial Research Organisation Multistage vacuum pump

Also Published As

Publication number Publication date
CZ2005176A3 (en) 2006-11-15

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