CA1157832A - Two stage stepped piston air compressor - Google Patents
Two stage stepped piston air compressorInfo
- Publication number
- CA1157832A CA1157832A CA000365319A CA365319A CA1157832A CA 1157832 A CA1157832 A CA 1157832A CA 000365319 A CA000365319 A CA 000365319A CA 365319 A CA365319 A CA 365319A CA 1157832 A CA1157832 A CA 1157832A
- Authority
- CA
- Canada
- Prior art keywords
- valves
- cylinder
- disposed
- cylinder head
- compressor according
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
Links
Abstract
TWO STAGE STEPPED PISTON
AIR COMPRESSOR
ABSTRACT OF THE DISCLOSURE
An air compressor with a cylinder has a stepped piston movably disposed therein which performs compression in both stroke directions to provide two-stage compression.
Each compression stage is associated with at least one inlet and outlet valve, whereby one outlet opening of a lower compression stage is connected with an inlet opening of a higher compression stage. All valves are disposed on the upper side of the compressor in the vicinity of the cylinder head. The compressor has few individual parts and the valves are easily accessible for maintenance.
AIR COMPRESSOR
ABSTRACT OF THE DISCLOSURE
An air compressor with a cylinder has a stepped piston movably disposed therein which performs compression in both stroke directions to provide two-stage compression.
Each compression stage is associated with at least one inlet and outlet valve, whereby one outlet opening of a lower compression stage is connected with an inlet opening of a higher compression stage. All valves are disposed on the upper side of the compressor in the vicinity of the cylinder head. The compressor has few individual parts and the valves are easily accessible for maintenance.
Description
1 ~5 7832 ~ACKGI~IND 01~ Tl-IE3 I NV~N'I' ION
The invention relatos to ~n air compzessor with a stepped piston movably disposed in a cylinder and which performs compression in both stroke directions, whereby each compres sion stage is associated with at least one inlet and one outlet valve t and whereby an outlet opening of a lower compression stage is connected with an inlet opening of a higher comprossion sta~e.
Air compressors with two compression stages are used to produce compressed air for the brake system in trucks.
The compressor is flanged to the vehicle motor and is driven continuously. Because of the continuous drive, a pressure regulator opens a suctions valve of the first stage when the intended pressure is reached. The dead volume of the second stage must be such that the compressor "runs dead" under the lowest operating pressure of the system. It is also possible to arrange a pressure regulator in the supply line of the compressor, whereby the regulator opens the supply line to the atmosphere when a prescribed high pressure is reached.
The provision of compression in both stroke directions assures smooth running and a compact construction. The latter is particularly important because of the limited available space in the engine compartment of a truck.
The use of this type of stepped piston compressor to produce compressed air for the brake system and for starting diesel truck engines is described in ~he magazine "Diesel And Gas Turbine Progress" of September 1969.
The stages of a stepped piston compressor are necessarily disposed in differen~ planes of the cylinder. In known I ~S7~
two-stacle cornpressors the valve-; o~ the ~irst Sta~Je are disposed above or at the side oE the upper end o~ the cylinder in the vicinity of the cylinder head. This enables the inlet and outlet valves to be designed S independently oÇ each other or, in other embodiments, to be combined with each other, i.e. the same valve can be provided with inlet and outlet ~unctions. The separate inlet and outlet valves of the second stage are disposed in the lower portion of the cylinder.
These known compressors exhibit various disadvantages.
They have a great number of individual parts and are therefore expensive. The different locations of the valves makes mounting difficult. Depending on the placement of the compressor on the vehicle motor, the side inlet and outlet valves of the second stage are either inaccessible or only accessible with a great deal of difficulty. To correct or check them the entire compressor must be removed. Maintenance and repair costs are therefore very high.
SUMMARY~ OF_THE INVENTION
It is an object of this invention to eliminate these disadvantages and to provide a simple two-stage, stepped piston air compressor having fewer individual parts and a design which is more accessible for servicing. This object is achieved by arranging all valves in the upper portion of the compressor, near the cylinder head.
~_ 3 _ 1 ~57~32 More speciEical].y, the invention consists o~ the provision in an air compressor including a cy]inder having two portions o~ different diameter, a stepped piston reciprocatingly disposed in sa:id cylinder to deEine low and high compression chambers in which said piston respectively performs compression in opposite stroke directions, a cylinder head closing the low compression chamber at one end o~ said cylinder, air inlet and outlet: openings associated wi.th each compression chamber, at ].east one inlet and one outlet valve associated with each compression chamber and the outlet opening o the low pressure chamber communicating with the inlet opening oE the high pressure chamber, the improvement comprising: all of said inlet and outlet valves being disposed at said one end of said cylinder proximate said cylinder head to enable easy access to said valves for maintenance and repair by the removal of said cylinder head.
BRIEF DESCRIPTION OF THE DRAWINGS
_ . . . .
Figs. 1 and 2 show two embodiments of an air compressor according to the invention each in schematic cross section.
-- 3a -,, ~ 157832 D~TA:rLEr) De~;cRIPTIoN or; THE PREP~RR~D EMBODI~NTS
In an air cooled stepped piston compressor according to Fig. 1, a cylinder 1 pro-vided with cooling fins 2 is formed in one piece with a drive shaft housing 3. A stepped piston 4 capable of reciprocating in cylindor 1 is driven by a drive shaft 5 and a pis~on rod 6.
A lower portion 7 of the p:iston 4 reciprocates in a lower bore section 8 of cylinder l and is sealed relative to the cylinder wall by piston rings 9. An upper, larger dia~
meter portion 10 of piston 4 reciprocatos in a correspondingly widened bore section 11 of cylinder 1 and is sealed relative to the cylinder wall by piston ring 12.
A cylinder head 13 provided with cooling fins 2 is screwed onto cylinder 1. Compressor valves 14 and 15 are disposed in this cylinder head 13. A further valve 16 is arranged on the upper surface of cylinder 1 directly beneath the cylinder head.
The valves 14-16 are non-return tongue valves, whose strokes are determined by the thickness of a seal 25 arranged between the cylinder head 13 and the cylinder 1. The thick-ness of the seal, i.e. the valve stroke, can be in the range of approximately 2 mm.
The compressor operates as follows:
During its downward stroke the piston 4 aspirates air through a filter 18 screwed into the cylinder head 13 and through the inlet valve 14 into a compression chamber 19 of the first stage. During the upward stroke the air is 1 157~332 comprcssed and urge(l ~ilrolJgh the valve 15 and cooling pipo 20 into compress:ion charllber 21 of the second stage.
The valve 15 simultaneously serves as an outlet valve from the first stage and an inlet va]ve to the second stago.
This is made possible by directing the air through an ang]ed channel 22 in the cylinder head 13. The volume of the channel 22 is included in tlle dead volume of the first com-pression chaMber l9.
Similarly, the volume of cooling pipe 20 is .included in the dead volume of the second compression stage. As is clear from Fig. 1, the second compression chamber comprises the two cooling pipes 20, 24 and the annular chamber 21 between the piston surface 23 and the expanded bore section 11 of the cylinder 1. The total dead volume is desirably about 5 to 10~ because this enables a very intensive cooling of the air in the second stage and "dead running" during idling.
The two cooling pipes 20, 24 are surrounded on all sides by the fins 2.
During its downward stroke the piston 4 further compresses zo the air to the final pressure and moves it through the cooling pipe 24 and the outlet valve 16 into the air exit opening 26, which is machined in cylinder head 13.
The second embodiment according to Fig. 2 is water-cooled without cooling fins, having water-filled cooling chambers 27 in place thereof, which are supplied with coolant through the water entrance opening 28. The water discharge opening is designated by numeral 29.
~ 157~3~
'I`ho cylinder head arrangerllellt consists of the actual cylinder head 30, a first soal 31, a valve plate 32 and a second seal 33. I:our tongue valves 34-37 are disposed on the valve plate 32, whereby the seal 31 above the plate 32 ancl the seal 33 below the plate 32 again determine the valve strokes.
The remaining portions of the compressor aro ormed similar to the Pig. 1 embodiment, and are numerically desig-nated accordingly.
The eylinder head combination 30 33 is serewed to the cylinder 1. The first compression chamber 19 is associated with inlet valve 34 and outlet valve 35, while the seeond compression chamber 21 is associated with inlet valve 36 and outlet valve 37. The air feed and diseharge of the second stage is via the water-eooled tubes 20,24, the volume of whieh must again be ineluded in the dead volume of the seeond eompression ehamber 21.
As compared to known air compressors having stepped pistons, the above-deseribed embodiments result in the following advantages:
- All valves are arranged on the upper side of the eompressor in the vicinity of the cylinder head. They are easily accessible for repair and maintenance costs are very low.
- When all valves are disposed on a single plate (as in the second embodiment), they can easily be replaced during an inspection. Accordingly, the entire valve plate together 1 1~7~33~
with the valvos can bc rcplacccl as a unit aftcr rcmoval of tho cylindcr hoad. This assuros a substantial simplification of inspoction and mounting.
- Thc air compressor has fewer components than known compressors. Thc material costs arc therefore lower and thc procurement of replace~ment parts is facilita~cd.
- As a result of the intensive cooling of the comprossion chamber of the second stage, the operating temporatures aro relatively low and service life is high.
The invention relatos to ~n air compzessor with a stepped piston movably disposed in a cylinder and which performs compression in both stroke directions, whereby each compres sion stage is associated with at least one inlet and one outlet valve t and whereby an outlet opening of a lower compression stage is connected with an inlet opening of a higher comprossion sta~e.
Air compressors with two compression stages are used to produce compressed air for the brake system in trucks.
The compressor is flanged to the vehicle motor and is driven continuously. Because of the continuous drive, a pressure regulator opens a suctions valve of the first stage when the intended pressure is reached. The dead volume of the second stage must be such that the compressor "runs dead" under the lowest operating pressure of the system. It is also possible to arrange a pressure regulator in the supply line of the compressor, whereby the regulator opens the supply line to the atmosphere when a prescribed high pressure is reached.
The provision of compression in both stroke directions assures smooth running and a compact construction. The latter is particularly important because of the limited available space in the engine compartment of a truck.
The use of this type of stepped piston compressor to produce compressed air for the brake system and for starting diesel truck engines is described in ~he magazine "Diesel And Gas Turbine Progress" of September 1969.
The stages of a stepped piston compressor are necessarily disposed in differen~ planes of the cylinder. In known I ~S7~
two-stacle cornpressors the valve-; o~ the ~irst Sta~Je are disposed above or at the side oE the upper end o~ the cylinder in the vicinity of the cylinder head. This enables the inlet and outlet valves to be designed S independently oÇ each other or, in other embodiments, to be combined with each other, i.e. the same valve can be provided with inlet and outlet ~unctions. The separate inlet and outlet valves of the second stage are disposed in the lower portion of the cylinder.
These known compressors exhibit various disadvantages.
They have a great number of individual parts and are therefore expensive. The different locations of the valves makes mounting difficult. Depending on the placement of the compressor on the vehicle motor, the side inlet and outlet valves of the second stage are either inaccessible or only accessible with a great deal of difficulty. To correct or check them the entire compressor must be removed. Maintenance and repair costs are therefore very high.
SUMMARY~ OF_THE INVENTION
It is an object of this invention to eliminate these disadvantages and to provide a simple two-stage, stepped piston air compressor having fewer individual parts and a design which is more accessible for servicing. This object is achieved by arranging all valves in the upper portion of the compressor, near the cylinder head.
~_ 3 _ 1 ~57~32 More speciEical].y, the invention consists o~ the provision in an air compressor including a cy]inder having two portions o~ different diameter, a stepped piston reciprocatingly disposed in sa:id cylinder to deEine low and high compression chambers in which said piston respectively performs compression in opposite stroke directions, a cylinder head closing the low compression chamber at one end o~ said cylinder, air inlet and outlet: openings associated wi.th each compression chamber, at ].east one inlet and one outlet valve associated with each compression chamber and the outlet opening o the low pressure chamber communicating with the inlet opening oE the high pressure chamber, the improvement comprising: all of said inlet and outlet valves being disposed at said one end of said cylinder proximate said cylinder head to enable easy access to said valves for maintenance and repair by the removal of said cylinder head.
BRIEF DESCRIPTION OF THE DRAWINGS
_ . . . .
Figs. 1 and 2 show two embodiments of an air compressor according to the invention each in schematic cross section.
-- 3a -,, ~ 157832 D~TA:rLEr) De~;cRIPTIoN or; THE PREP~RR~D EMBODI~NTS
In an air cooled stepped piston compressor according to Fig. 1, a cylinder 1 pro-vided with cooling fins 2 is formed in one piece with a drive shaft housing 3. A stepped piston 4 capable of reciprocating in cylindor 1 is driven by a drive shaft 5 and a pis~on rod 6.
A lower portion 7 of the p:iston 4 reciprocates in a lower bore section 8 of cylinder l and is sealed relative to the cylinder wall by piston rings 9. An upper, larger dia~
meter portion 10 of piston 4 reciprocatos in a correspondingly widened bore section 11 of cylinder 1 and is sealed relative to the cylinder wall by piston ring 12.
A cylinder head 13 provided with cooling fins 2 is screwed onto cylinder 1. Compressor valves 14 and 15 are disposed in this cylinder head 13. A further valve 16 is arranged on the upper surface of cylinder 1 directly beneath the cylinder head.
The valves 14-16 are non-return tongue valves, whose strokes are determined by the thickness of a seal 25 arranged between the cylinder head 13 and the cylinder 1. The thick-ness of the seal, i.e. the valve stroke, can be in the range of approximately 2 mm.
The compressor operates as follows:
During its downward stroke the piston 4 aspirates air through a filter 18 screwed into the cylinder head 13 and through the inlet valve 14 into a compression chamber 19 of the first stage. During the upward stroke the air is 1 157~332 comprcssed and urge(l ~ilrolJgh the valve 15 and cooling pipo 20 into compress:ion charllber 21 of the second stage.
The valve 15 simultaneously serves as an outlet valve from the first stage and an inlet va]ve to the second stago.
This is made possible by directing the air through an ang]ed channel 22 in the cylinder head 13. The volume of the channel 22 is included in tlle dead volume of the first com-pression chaMber l9.
Similarly, the volume of cooling pipe 20 is .included in the dead volume of the second compression stage. As is clear from Fig. 1, the second compression chamber comprises the two cooling pipes 20, 24 and the annular chamber 21 between the piston surface 23 and the expanded bore section 11 of the cylinder 1. The total dead volume is desirably about 5 to 10~ because this enables a very intensive cooling of the air in the second stage and "dead running" during idling.
The two cooling pipes 20, 24 are surrounded on all sides by the fins 2.
During its downward stroke the piston 4 further compresses zo the air to the final pressure and moves it through the cooling pipe 24 and the outlet valve 16 into the air exit opening 26, which is machined in cylinder head 13.
The second embodiment according to Fig. 2 is water-cooled without cooling fins, having water-filled cooling chambers 27 in place thereof, which are supplied with coolant through the water entrance opening 28. The water discharge opening is designated by numeral 29.
~ 157~3~
'I`ho cylinder head arrangerllellt consists of the actual cylinder head 30, a first soal 31, a valve plate 32 and a second seal 33. I:our tongue valves 34-37 are disposed on the valve plate 32, whereby the seal 31 above the plate 32 ancl the seal 33 below the plate 32 again determine the valve strokes.
The remaining portions of the compressor aro ormed similar to the Pig. 1 embodiment, and are numerically desig-nated accordingly.
The eylinder head combination 30 33 is serewed to the cylinder 1. The first compression chamber 19 is associated with inlet valve 34 and outlet valve 35, while the seeond compression chamber 21 is associated with inlet valve 36 and outlet valve 37. The air feed and diseharge of the second stage is via the water-eooled tubes 20,24, the volume of whieh must again be ineluded in the dead volume of the seeond eompression ehamber 21.
As compared to known air compressors having stepped pistons, the above-deseribed embodiments result in the following advantages:
- All valves are arranged on the upper side of the eompressor in the vicinity of the cylinder head. They are easily accessible for repair and maintenance costs are very low.
- When all valves are disposed on a single plate (as in the second embodiment), they can easily be replaced during an inspection. Accordingly, the entire valve plate together 1 1~7~33~
with the valvos can bc rcplacccl as a unit aftcr rcmoval of tho cylindcr hoad. This assuros a substantial simplification of inspoction and mounting.
- Thc air compressor has fewer components than known compressors. Thc material costs arc therefore lower and thc procurement of replace~ment parts is facilita~cd.
- As a result of the intensive cooling of the comprossion chamber of the second stage, the operating temporatures aro relatively low and service life is high.
Claims (8)
1. In an air compressor including a cylinder having two portions of different diameter, a stepped piston reciprocatingly disposed in said cylinder to define low and high compression chambers in which said piston respectively performs compression in opposite stroke directions, a cylinder head closing the low compression chamber at one end of said cylinder, air inlet and outlet openings associated with each compression chamber, at least one inlet and one outlet valve associated with each com-pression chamber and the outlet opening of the low pressure chamber communicating with the inlet opening of the high pressure chamber, the improvement comprising:
all of said inlet and outlet valves being disposed at said one end of said cylinder proximate said cylinder head to enable easy access to said valves for maintenance and repair by the removal of said cylinder head.
all of said inlet and outlet valves being disposed at said one end of said cylinder proximate said cylinder head to enable easy access to said valves for maintenance and repair by the removal of said cylinder head.
2. A compressor according to claim 1, further comprising a valve plate disposed between said cylinder head and said cylinder, and wherein all said valves are disposed in said valve plate.
3. A compressor according to claim 2, wherein the valves are formed as tongue valves, and further comprising seals disposed on both sides of said valve plate, the thickness of which seals determines the stroke of said valves.
4. A compressor according to claim 1, further comprising cooling tubes connected with respective ones of said valves for the supply and discharge of air to said high compression chamber.
5. A compressor according to claim 4, wherein the volume of said cooling tubes is part of the total dead volume of said high compression chamber.
6. A compressor according to claim 1, wherein said valves are disposed between said cylinder head and said one end of said cylinder.
7. A compressor according to claim 1, further comprising a seal between said cylinder head and said cylinder, the thickness of which seal determines the stroke of said valves, and wherein said valves are formed as tongue valves.
8. A compressor according to claim 7, wherein an outlet valve for said low compression chamber also serves as an inlet valve for said high compression chamber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000365319A CA1157832A (en) | 1980-11-24 | 1980-11-24 | Two stage stepped piston air compressor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000365319A CA1157832A (en) | 1980-11-24 | 1980-11-24 | Two stage stepped piston air compressor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1157832A true CA1157832A (en) | 1983-11-29 |
Family
ID=4118533
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000365319A Expired CA1157832A (en) | 1980-11-24 | 1980-11-24 | Two stage stepped piston air compressor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1157832A (en) |
-
1980
- 1980-11-24 CA CA000365319A patent/CA1157832A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |