EP3667083A1

EP3667083A1 - Air pump system

Info

Publication number: EP3667083A1
Application number: EP18211321.7A
Authority: EP
Inventors: Mika Lokkinen
Original assignee: Picote Solutions Inc
Current assignee: Picote Solutions Inc
Priority date: 2018-12-10
Filing date: 2018-12-10
Publication date: 2020-06-17

Abstract

The present disclosure concerns an air pump system based on the idea of having an air cylinder (10, 11, 12) and a disc (22) moving inside the cylinder along a rotatable shaft (20) to provide pumping action. The pumping action is achieved with a motor (80) rotating the shaft and a motor controller (90) driving said motor (80). Both ends (11, 12) of the cylinder have inlet valves (40) and outlet valves (44, 45) so that back and forth movement of the disc (22) is used for pumping air during both movement directions of the disc (22).

Description

FIELD OF THE INVENTION

The present invention relates to a motorized air pumps and especially to low-pressure air pumps without an air tank.

BACKGROUND OF THE INVENTION

Installed pipelines in buildings and underground can be rehabilitated without opening structures or digging the ground. The trenchless rehabilitation allows a quick and durable rehabilitation of pipes within buildings and underground pipelines. A resin impregnated liner is installed in a pipe with an inversion drum using air pressure to invert the liner into the pipe. Once the liner is installed air pressure is maintained on an elevated level until the resin within the liner settles and the liner forms a rigid pipe against the inner surface of the old pipe. A drop in air pressure inside the pipe during a settling period may cause collapse of the liner which blocks or at least severely restricts the flow of fluids in the pipe.
Air compressors have been used both for inverting the liner and to maintain air pressure inside a newly installed liner. Air compressors typically produce compressed air having high pressure but low output volume whereas high volume of low-pressure air would be desirable. Pressure regulators are mandatory during lining operations due to the high output pressure of air compressors. Typically about 50 kPa over the atmospheric pressure is needed in lining operations and typical compressor produces output of 700 to 1000 kPa. A pressure level like that in a liner would tear the liner instantly and it can happen due to malfunction in the pressure regulator.
Another problem is the output volume of air compressors. Typical portable electric air compressors produce 20 to 100 litres/min of air. If there is a minor leak in a newly installed liner, the air compressor might have to either run constantly or start and stop every minute or so. Air compressors are not designed for that and their operating life shortens significantly is this type of use. This either causes significant delays or requires a spare unit at hand all the time.
There is also another problem when lining pipes of residential buildings. Air compressors make a loud noise which tends to annoy residents of the building and sometimes one of the residents unplugs the air compressor at night. This leads to a failed lining and requires significant effort to remove the failed lining and reline the pipe.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a device for producing compressed air that is more suitable for pipe lining operations than current air compressors.
One aspect of the present invention is an air pump system based on the idea of having an air cylinder and a disc moving inside the cylinder along a rotatable shaft to provide pumping action. The pumping action is achieved with a motor rotating the shaft and a motor controller driving said motor. Both ends of the cylinder have inlet and outlet valves so that back and forth movement of the disc is used for pumping air during both movement directions of the disc.
The object of the invention is achieved with an air pump system of independent claim 1. Advantageous embodiments are presented in dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the present invention is described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 illustrates an isometric view of an air pump system according to an embodiment of the invention;
Figure 2 illustrates an isometric view of an air pump system according to an embodiment of the invention without protective cover;
Figure 3 illustrates an isometric section view of an air pump system according to an embodiment of the invention; and
Figure 4 illustrates detail A of Figure 3.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 2 illustrate an air pump system according to an embodiment of the invention and Figures 3 and 4 are section views showing insides of the air pump system.
An air pump system according to an embodiment of the present invention comprises an air cylinder which is delimited by a tubular side wall 10, a first end portion 11 and a second end portion 12. The tubular side wall is preferably a tube having a circular cross-section and is made of metal or plastic, such as polyethylene or HDPE. The tubular side wall can be for example HDPE pipe having an inner diameter of 150-300 mm, e.g. 200 mm. The first end portion 11 and the second end portion 12 are made of metal or plastic, such as polyethylene or HDPE and attached to opposite ends of the tubular side wall to create an air cylinder. A seal or gasket can be used between the tubular side wall and said end portions to minimize leaking of air.
The air pump system also comprises a rotatable shaft 20. The shaft has a helically grooved or threaded surface and the shaft extends from said first end portion 11 to said second end portion 12 within the air cylinder. A motor 80 is provided and configured to rotate the shaft 20. Power from rotating shaft of the motor 80 is delivered to the rotating shaft 20 of the air pump system using conventional means, such as a belt, a chain, a set of pinions or any combination of the previously mentioned.
The air pump system also comprises a disc 22 inside the air cylinder dividing the air cylinder into two chambers, a first chamber 17 and a second chamber 18. The disc 22 is configured to move along said rotatable shaft 20 inside the air cylinder when said rotatable shaft 20 is rotated. The disc is substantially the same size in diameter as the inner diameter of the tubular side wall of the air cylinder. The space between the disc 22 and the inner tubular side wall can be sealed or made small enough to minimize air leak from one chamber to the other inside the air cylinder. The disc 22 is made of metal or plastic, such as polyethylene or HDPE. Preferably any contacting parts between the disc 22 and the tubular side wall 10 of the air cylinder are metal-plastic pairs so that metal always contacts and slides against plastic surface and plastic always contacts and slides against metal surface. Sliding metal-metal and plastic-plastic contacts are preferably avoided or eliminated.
The motor 80 is controlled and driven with a motor controller 90 which is preferably a frequency converter. The motor controller 90 has preferably a using interface for switching it on and off but also for changing settings, such as a desired pressure level or air volume output. The motor controller 90 has preferably one or more inputs for controlling the motor 80 based on external sensor data.
For example in an embodiment, the air pump system further comprises one or more sensors for detecting location of the disc 22 inside the air cylinder. The motor controller 90 is configured to receive said location of the disc 22 and configured to control the motor 80 based on said location of the disc 22. The motor controller e.g. detects that the disc 22 is coming close to the first end portion and slows down rotating speed and prepares to briefly stop the motor 80 and then change rotating direction and accelerate again in order to move the disc 22 close to the second end portion before returning back again. These functions can also be programmed into the motor controller 90 to function without external sensors.
In another example that can be used with or without the functionality of the previous example, the air pump system further comprises a pressure sensor configured to measure air pressure within an outlet air channel 46, 48. The motor controller 90 is configured to control the motor 80 based on the measured air pressure. A user of the air pump system can e.g. set a desired pressure level using the motor controller 90 and the motor controller drives the motor until the set pressure level is achieved based on the air pressure sensor data or until the pressure level reaches a certain threshold value based on the set pressure level.
The disc 22 that is driven with motor 80 changes volumes of the two chambers inside the air cylinder as the disc 22 moves along the rotatable shaft 20. Thus, air has to be provided into the air cylinder and moved out from the air cylinder. The air pump system comprises inlet air valves 40 on the first end portion 11 and the second end portion 12. The inlet valves 40 allow air to flow into the air cylinder when air pressure inside the air cylinder is lower than air pressure outside the air cylinder. Similarly, the inlet valves 40 prevent the flow of air from the air cylinder into outside the air cylinder, even when air pressure inside the air cylinder is higher than air pressure outside the air cylinder. The inlet valves 40 can consist of one or more orifices on the first and second end portions and an elastic or a flexible sheet or panel on the air cylinder side covering the orifices. Difference in air pressure over the sheet or panel twists the sheet or panel and allows air to flow into the air cylinder. Also other suitable well-known valve structures can be used instead.
The air pump system further comprises an outlet air channel 48 for output of pumped air through air outlet 49. The air outlet 49 can be equipped with a Camlock connector or some other type of connector for attaching a pipe liner to the air outlet 49. The pumped air flows into the outlet air channel through outlet air valves 44, 45 on the first end portion 11 and the second end portion 12. The outlet air valves allow air to flow from the air cylinder into the outlet air channel 48 when air pressure inside the air cylinder is higher than air pressure inside the outlet air channel 48. Similarly, the outlet valves 44, 45 prevent the flow of air from the outlet air channel into the air cylinder, even when air pressure inside the air cylinder is lower than air pressure inside the outlet air channel. Said outlet air valves can comprise, for example, an elastic element 45 outside the air cylinder and one or more orifices 44 in the air cylinder, preferably on the tubular side wall. The elastic element can be for example a rubber or silicone ring. In rest, or in balance state, the elastic element 45 blocks the one or more orifices 44 and prevents air flow through the orifices. The elastic element 45 is configured to expand into the outlet air channel 48 and allow air to flow from inside the air cylinder into the outlet air channel 48 through said one or more orifices 44 when air pressure inside the air cylinder is higher than air pressure in the outlet air channel 48. The outlet valves can also have construction similar to the inlet valves. Also other suitable well-known valve structures can be used instead.
When the motor 80 is rotated and the disc 22 moves within the air cylinder along the rotatable shaft towards the first end portion 11, air pressure in the first chamber 17 tends to rise and air pressure in the second chamber 18 tends to fall as the disc 22 moves away from the second end portion 12. The outlet valves allow compressed air in the first chamber to flow into the outlet air channel when air pressure rises enough. Similarly, the inlet valves allow new air to flow in to the second chamber 18 when air pressure in the second chamber 18 falls enough. As the disc 22 approaches the first end portion 11, the rotation of the rotatable shaft 20 is stopped and rotation direction of the motor is reversed and accelerated again. The disc 22 starts to move back towards the second end portion 12 and the first chamber 17 that pumped air into the outlet air channel 48 now draws new air in through the inlet valves 40 into the first chamber 17 of the air cylinder. At the same time the second chamber 18, air pressure starts to build up as the volume of the second chamber 18 decreases and eventually air is pumped from the second chamber into the outlet air channel 48.
Compared to a traditional air compressor, the air pump system of a preferred embodiment does not have a tank for storing high pressure air. In addition, air pressure in the whole system, including the air pump system and a pipe liner attached to the air outlet 49, gradually builds up without having a dangerously high air pressure anywhere in the system. Therefore pressure regulators are unnecessary and problems caused by malfunctioning pressure regulators are non-existent. The air pump system has higher output volume than an electric compressor of the same size and air pressure levels remain in the air pump system remain on safe level during operation. Minor leaks when maintaining air pressure in an installed liner can be compensated by slowly pumping air with the air pump system. Noise level can be kept much lower than with an air compressor using small volume high RPM piston.
In a preferred embodiment of the invention, the outlet air channel 48 or the air pump system comprises one or more ducts 46 extending between the first end portion 11 and the second end portion 12 thereby creating a fluid connection between the first end portion 11 and the second end portion 12 on outlet air channel side of the outlet air valves 44, 45. Fluid connection in this context means that fluid can freely flow between parts that have a fluid connection between them. In other words, the outlet air channel is a continuous space into which air can be pumped from both end portions 11, 12 of the air pump system and from which the pumped air can exit through air outlet 49. Said one or more ducts are preferably rigid tubes attached to the first end portion 11 and the second end portion 12 and thereby forming part of a frame structure of the air pump system but also delivering pumped air from one end portion to another end portion. Said rigid tubes can also be used to tighten said end portions 11, 12 against opposite ends of the tubular side wall 10. In an embodiment, said one or more ducts 46 can be any duct enabling flow of air between the first end portion 11 and the second end portion 12 outside the air cylinder. Preferably the air outlet 49 connected via outlet air channel 46, 48 to each of the outlet air valves 44, 45 of the air pump system.
In an embodiment of the invention, the air pump system further comprises a safety valve 42 in the outlet air channel 48. The safety valve is configured to release air from the outlet air channel 48 if air pressure inside the outlet air channel reaches a predetermined pressure level. The purpose of the safety valve is to protect a liner attached to the air outlet 49 of the air pump system and also the air pump system itself in case of a rare but possible failure that would increase air pressure inside the outlet air channel.
In an embodiment of the invention the air pump system further comprises one or more guides 16 for controlling position of said disc 22 and preventing rotation of said disc 22. The purpose of the position controlling is to keep the disc 22 in a plane perpendicular to rotation axis of the rotatable shaft 20. In an embodiment said one or more guides 16 are rods or tubes extending inside the air cylinder from said first end portion 11 through said disc 22 to said second end portion 12. Sais one or more guides can include sleeves, collars or flanges attached to one side or both sides of the disc 22 around said rods or tubes. Said rods or tubes can also be used to tighten said end portions 11, 12 against opposite ends of the tubular side wall 10. The rods or tubes are preferably made of metal or plastic, such as polyethylene or HDPE. Preferably any contacting parts between the disc 22 (or possible sleeves, collars or flanges) and the rods 16 in the air cylinder are metal-plastic pairs so that metal always contacts and slides against plastic surface and plastic always contacts and slides against metal surface. Sliding metal-metal and plastic-plastic contacts are preferably avoided or eliminated.
In an embodiment, said one or more guides comprise a longitudinal recess or groove, parallel to the rotatable shaft, on the inner wall of the tubular side wall 10 and a matching protrusion on the periphery of the disc 22. In an embodiment, said one or more guides comprise a longitudinal protrusion, parallel to the rotatable shaft, on the inner wall of the tubular side wall 10 and a matching recess or a groove on the periphery of the disc 22.
It will be obvious to a person skilled in the art that, as the technology advances, that the inventive concept can be implemented in various ways. The present invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

An air pump system comprising:
an air cylinder delimited by a tubular side wall (10), a first end portion (11) and a second end portion (12);

a rotatable shaft (20) having a helically grooved or threaded surface and extending from said first end portion (11) to said second end portion (12) within the air cylinder;

an outlet air channel (48, 49) for output of pumped air;

a motor (80) configured to rotate the rotatable shaft (20); and

a motor controller (90) for controlling the operation of the motor (80), wherein the air pump system is characterized in that it further comprises:
a disc (22) inside the air cylinder dividing the air cylinder into two chambers (17, 18), which disc is configured to move along said rotatable shaft (20) inside the air cylinder when said rotatable shaft (20) is rotated;

inlet air valves (40) on said first end portion (11) and said second end portion (12) allowing air to flow into the air cylinder when air pressure inside the air cylinder is lower than air pressure outside the air cylinder; and

outlet air valves (44, 45) on said first end portion (11) and said second end portion (12) allowing air to flow from the air cylinder into the outlet air channel (48) when air pressure inside the air cylinder is higher than air pressure inside the outlet air channel (48).
An air pump system according to claim 1, wherein the outlet air channel (48) further comprises one or more ducts (46) extending between said first end portion (11) and said second end portion (12) thereby creating a fluid connection between said first end portion (11) and said second end portion (12) on outlet air channel side of said outlet air valves (44, 45).
An air pump system according to claim 1 or 2, wherein the air pump system comprises an air outlet (49) connected via outlet air channel (46, 48) to each of the outlet air valves (44, 45) of the system.
An air pump system according to any one of claims 1 to 3, wherein the outlet air channel (48) further comprises a safety valve (42) configured to release air from the outlet air channel (48) if the pressure inside the outlet air channel reaches a predetermined pressure level.
An air pump system according to any one of claims 1 to 4, wherein the air pump system further comprises a pressure sensor configured to measure air pressure within the outlet air channel (48), wherein the motor controller (90) is configured to control the motor (80) based on the measured air pressure.
An air pump system according to any one of claims 1 to 5, wherein the air pump system further comprises one or more guides (16) for controlling position of said disc (22) and preventing rotation of said disc (22).
An air pump system according to any one of claims 1 to 6, wherein said one or more guides (16) are rods or tubes extending inside the air cylinder from said first end portion (11) through said disc (22) to said second end portion (12).
An air pump system according to any one of claims 1 to 7, wherein said outlet air valves comprise an elastic element (45) outside the air cylinder, wherein the elastic element (45) is configured to expand into the outlet air channel (48) and allow air to flow from inside the air cylinder into the outlet air channel (48) through one or more orifices (44) of the air cylinder.
An air pump system according to any one of claims 1 to 8, wherein the air pump system further comprises one or more sensors for detecting location of the disc (22) inside the air cylinder.
An air pump system according to claim 9, wherein the motor controller (90) is configured to receive said location of the disc (22) and configured to control the motor (80) based on said location of the disc (22).
An air pump system according to any one of claims 1 to 10, wherein the tubular side wall (10) of the air cylinder is made of plastic.
An air pump system according to any one of claims 1 to 11, wherein the tubular side wall (10) of the air cylinder has a circular cross-section.