JP2005535822A - Control method for controlling gas flow in a compressor - Google Patents

Abstract

A control method for controlling the gas flow by a compressor in which a volume is expanded during an intake stroke and the intaken volume of gas is compressed and taken out through a non return valve ( 6 ) for outflow and/or an operable outlet valve ( 3 ) during an evacuation stroke, and in which the compressor has a controllable inlet valve ( 2 ) that is pneumatically, hydraulically or electromagnetically operable and that is opened and closed upon basis of a signal from a control system. The inlet valve ( 2 ) is kept closed during at least a part of an intake stroke.

Description

  The present invention is for controlling gas flow in a compressor in which the volume is expanded during the intake stroke and the gas introduction volume is compressed during the exhaust stroke and taken out via an evacuation check valve and / or operable valve. The control method relates to a control method in which the compressor is operated by air pressure, hydraulic pressure, or electromagnetic action and has a controllable inlet valve that opens and closes based on a signal from a control device.

  This type of compressor has several embodiments, but piston compressors are the most common and are often referred to as positive displacement compressors. In order to take advantage of the present invention, the compressor must have a controllable inlet valve. However, the compressor preferably has an inflow check valve that can be closed and a controllable outlet valve. The present invention addresses the changing demands of pressurized gas with low energy consumption and environmental impact for known methods.

The present invention can be applied to positive displacement compressors for industrial uses such as vehicles, vehicle engines, and fuel cells.
The present invention is put into practical use through the use of a control device. The control unit software is critical to its function. The software used for putting the present invention into practical use can be applied as a part of a large control device such as an engine operation device.

  Since the piston compressor is the most common positive displacement compressor, the present invention will be described by way of illustration based on the structure of the piston compressor.

  Positive displacement compressors, particularly piston compressors, are usually operated at a constant and relatively low rotational speed. Typically, the inlet and outlet valves are check valves that have a limiting effect on gas flow at high revolutions per minute.

  Flow control is usually performed by starting the compressor when the pressure in the tank connected to the compressor drops below a certain level, and by stopping the compressor when a certain pressure level is obtained. . Frequent starting and stopping causes great wear and energy consumption.

  According to another general type of control, when a certain pressure is obtained in the tank connected to the compressor, the gas flow to the inflow check valve is blocked by the shut-off valve, while the operation of the compressor is , Allowed to continue with the cycle without compressing the gas. When the pressure in the tank drops below a certain level, gas flow is once again allowed.

  When the demand for pressurized gas is not very frequent, the first type of control is most economical. As demands become more frequent, the latter type of control becomes substantially more economical. However, the closing / opening of the gas flow is relatively slow. This means that multiple cycles are performed with the shortest possible interruption without compressing the gas. Furthermore, slow closure / opening results in considerable flow loss. Accordingly, the tank and compressor must be larger than if the gas flow to the compressor is temporarily interrupted as a single cycle. Furthermore, rapid closure / opening reduces flow loss.

  The present invention produces an unrestricted gas flow as described above in the case of a check valve, where the air flow is quickly interrupted / released and interrupted for a short period such as one cycle. Thus, not only compressor and tank sizes, but also energy consumption and environmental impact can be reduced with respect to conventional methods.

  The object of the present invention is to provide a method for controlling the gas flow in a compressor, avoiding the above-mentioned drawbacks, responding to the changing demands of pressurized gas with faster control and more even pressure levels, while at the same time To achieve less energy consumption and environmental impact on the method.

  The object of the present invention is achieved by a compressor in which the volume is expanded during the intake stroke and the gas introduction volume is compressed during the exhaust stroke and taken out via an outlet check valve. It has a controllable inlet valve that operates by pressure or electromagnetic action and opens and closes based on a signal from the control device. The control method is characterized in that the inlet valve is closed during at least part of the intake stroke. Other features are set forth in the following description and claims.

Here, the compressor is referred to as a positive displacement compressor, in particular a piston compressor.
Controllable inlet valve, controllable outlet valve, inflow check valve, outflow check valve, and similar expressions may include other possible embodiments that use multiple valves of the type of valve. Is intended.

  It is also conceivable that the compressor may be constituted by a plurality of compressors, for example a plurality of cylinder / piston compressors. With the cylinder-piston compressor, each cylinder forms an individual piston compressor, and each individual compressor operates according to the description and the claims.

  A common feature of positive displacement compressors is that the volume is expanded during the intake stroke. When the volume is expanded, the volume is filled with a gas, such as air, and the gas flows through a valve, usually a check valve. At the end of the intake stroke, the volume surrounding the introduced gas is compressed and the gas is evacuated through a valve, usually a check valve. Piston compressors are the most common positive displacement compressors, where the volume that is expanded and the volume that is compressed are the same. If the volume to be expanded is not the same as the volume to be compressed, for example, there is a rotary displacement compressor. In a piston compressor, the piston moves in a cylinder between two dead centers (referred to as upper dead center and lower dead center, respectively). The movement of the piston from the upper dead center to the lower dead center results in a volume that is expanded during the intake stroke (as expressed in the prerequisites of claim 1). The movement of the piston from the upper dead center to the lower dead center results in a volume (represented in the above prerequisites) that is compressed during the exhaust stroke and taken out via the check valve for outflow.

  There are usually an inflow check valve and an outflow check valve located at the top dead center. When the piston moves from upper dead center to lower dead center during the intake stroke, the volume is expanded between the piston and upper dead center. The volume is filled with gas through an inflow check valve during movement. During the exhaust stroke, the piston moves from lower dead center to upper dead center, and the volume between the piston and upper dead center is compressed. Initially, the enclosed gas goes nowhere. Thus, the pressure increases within a gradually decreasing volume. When the pressure of the enclosed gas is sufficiently higher than the pressure on the other side of the outflow check valve, the latter is opened and the gas is discharged during the continued movement of the piston towards the upper dead center. The exhaust stroke that follows during the intake stroke is referred to herein as a cycle. A complete cycle is accomplished with one revolution of the compressor shaft.

  With reference to the above description of the background, significant benefits are achieved if interruption occurs in a short period, such as one cycle. With the aid of a controllable valve according to the first definition in the above description, a single intake stroke is carried out with the closed inlet valve. This means that no gas is introduced during the intake stroke. This automatically generates a state in which no gas is discharged during the exhaust stroke. Therefore, the gas flow is interrupted during one cycle. The intake stroke performed with the inlet valve closed is called a closed intake stroke.

  In order to be able to carry out the invented method, it is required that the controllable valve is mainly a controllable inlet valve. However, it is preferred that the embodiment has a controllable outlet valve apart from the already existing spill check valve. The controllable valve allows a much larger air flow than is possible for a contemporary check valve in today's compressors. Thus, a considerably higher rpm is allowed and a smaller piston compressor can be used than today. By applying an inflow check valve together with a gas conduit that can be closed, for example with the aid of mechanical technology based on obtaining a certain amount of air at a certain pressure, there is a considerable advantage of having an assist function. can get. If the controllable inlet and / or outlet valves fail, the assist function will work. By the use of a controllable inlet valve, the latter is closed during a complete intake stroke (referred to herein as a closed intake stroke), but may also be part of the intake stroke. This partial period is variable from cycle to cycle. Thus, the method according to the invention relies on closing the inlet valve during at least part of the intake stroke to control the outflow volume during the exhaust stroke. It is further apparent that the closure occurs during a sequence in which normal intake strokes are normally present, and that the compressor operates in multiple subsequent cycles of intake and exhaust strokes.

  According to the control strategy characterizing the control method, i.e. by using the frequency of the cycle in the closed intake stroke, the amount of compressed gas required at each moment is supplied, the frequency at that time being 0% of the number of revolutions per minute By varying between 100%, significant economic operation is achieved. For example, if the controller selects a frequency of 0%, a cycle with a closed intake stroke is not performed, but gas is supplied at each revolution. At a frequency of 100%, each cycle is executed with a closed intake stroke. At a frequency of 50% with a closed intake stroke, each cycle is executed during each second rotation. At a frequency of 20% with a closed intake stroke, each cycle is executed at the fifth rotation. At a frequency of 10% with a closed intake stroke, each cycle is executed at every tenth rotation. Thus, a cycle with a closed intake stroke is executed, for example, with each second, third, fourth, fifth rotation, etc. During the remaining cycle / rotation period, gas is supplied during the intake stroke. At frequencies between 50% and 100%, a cycle with a closed inspiratory stroke is directly followed by one, two or more subsequent cycles with a closed inspiratory stroke, or a series of subsequent cycles. For example, in an 80% cycle with a closed intake stroke, an appropriate distribution should have one cycle with a normal intake stroke after a continuous series of 4 cycles with a closed intake stroke, then closed Another continuous series of 4 cycles with a given intake stroke is followed by another cycle with a normal intake stroke etc. In order to keep the pressure level in the tank as uniform as possible with respect to the pressurized gas associated with the compressor and to make the tank as small as possible, the controller is generally in between each cycle or closed air intake. It should be characterized that the same number of revolutions should be performed between each successive series of cycles with a stroke. The present invention has also been described to address the immediate demand for compressed gas by using the frequency of cycles with a normal inspiratory stroke and provide the same effect.

  Another characterizing control strategy of the control method advantageously combined with the frequency control described above is to respond to the immediate demand for compressed gas through the use of cycles. The cycle in that case is closed somewhere in the piston path from the upper dead center to the lower dead center during a part of the intake stroke when the controllable inlet valve is determined by the controller. This part of the inspiratory stroke in question can vary from cycle to cycle. This advantageous possibility minimizes the storage tank for compressed gas as much as possible, or allows the tank to be formed by a conduit that directs pressurized gas from the compressor to the equipment where the gas is to be used. The possibility of minimizing the storage space for compressed gas is achieved by variably providing substantially the same amount of compressed gas as the amount consumed at a given moment following the changing consumption. .

  Because the flow loss is significantly reduced, the controllable inlet valve, and possibly the outlet valve, allows a considerably increased flow capacity for a given volumetric capacity, the latter being the piston 2 in the piston compressor. Between the two dead points is called the internal volume of the cylinder. This means, for example, that a piston compressor can be connected to the engine shaft of the vehicle engine and that the rotational speed per minute follows the rotational speed of the engine directly or by gear reduction. In the case of embodiments involving vehicles, the term gas should be replaced by air. For example, piston compressors are used for engine combustion, for the controllable pneumatically actuated valves of the engine and / or the compressor itself, for air-assisted fuel injection, for brake devices etc. It may be used to create air. The feature is that due to the high rotational speed per minute and the high demand for compressed air in the case of engine operation, the inlet valve is closed after the piston reaches the bottom dead center, so that before the piston reaches its bottom dead center Compared to the closed case, a large amount of air to be compressed can be supplied. Another characteristic way to increase the capacity of the compressor during engine operation is to use a compressor conduit for supplying air to an existing air conduit to an engine with pressurized air generated by an exhaust gas turbo or screw compressor. Is to connect. A connection downstream of an existing intercooler would be preferred. Connection to the air supply vehicle engine conduit downstream of the air filter and upstream of any existing throttle is appropriate without the need for equipment to compress the air because the air passes through the air purification filter.

  The above-described support function that is particularly useful during engine operation is also a feature of the present invention. If necessary, it defines features that make it a particular ability to provide compressed air or any other gas that is always at hand. The assist function is advantageous as described above when any controllable valve fails. However, if there is no residual pressure in the pressure tank or conduit for pressurized air, it will immediately determine the air pressure to be used for starting the engine with air assisted fuel injection, for example by an electric start engine. Generate the possibility of establishing. For example, the same applies if there is a controllable valve that is pneumatically actuated. The inflow check valve and the outflow check valve each have a large flow capacity and are controllable pneumatic, hydraulic or electromagnetically actuated closure located near or upstream of the inflow check valve If there is a member, a cycle with a closed intake stroke or a controllable closure member is part of the intake stroke in question (somewhere in the piston path from the upper dead center to the lower dead center. In order to execute the frequency of cycles that are closed during the period, the principle of the support function is required in advance.

  As described above, the method includes embodiments in which the controllable valve for inflow can operate with pneumatic, hydraulic or electromagnetic action. The method is characterized in that the controllable outlet valve opens in relation to the pressure balance obtained between the gas to be discharged and the gas on the opposite side of the outlet valve. It is important to avoid contact between the piston and the outlet valve, so the preferred embodiment is that the outlet valve opens in the direction from the cylinder, i.e. the direction of movement of the piston during compression and exhaust. It is characterized. If the outlet valve opens in the opposite direction, i.e. in the direction of movement of the piston, the outlet valve must close fast enough to avoid piston contact. In this case, a combination of a controllable outlet valve and an outlet check valve is advantageous and is important so that the amount of compressed gas that would otherwise remain can be evacuated. However, when a sufficiently small distance exists for complete closure of the outlet valve, very little piston contact is not detrimental and can benefit from good exhaust. However, this implies that the outlet valve is moved along exactly the same access / direction as the piston.

  From the above and the following description, it is clear that there is an absolute need for an electromagnetic-based control device with the necessary sensors and other components, including computers / programs developed for special purposes. .

  FIG. 1 is a schematic drawing of an embodiment showing a compressor cylinder with a piston 1. The piston 1 is in a moving state during the intake stroke, and air (or any other gas) is flowing through the inlet valve 2. The inlet valve 2 and the closed outlet valve 3 are constituted by controllable valves operating with pneumatic, hydraulic or electromagnetic action. Circuit 4 is used to actuate valves 2 and 3. The control unit 5 is operatively connected to a circuit 4 for signal controlling the circuit and the valves 2 and 3 connected to the circuit. The compressed air is transferred via the conduit 7 to the tank 8 via the outlet valve 3 and / or the check valve that allows the gas 6 to flow out.

  A sensor 9 in the tank 8 operatively connected to the control unit 5 provides the control unit 5 with continuous information about the pressure in the tank. A sensor 10 located on a graduated arc 12, mounted on the compressor shaft 11 and operatively connected to the control unit 5 controls to count the revolutions per minute and the piston position in the cylinder. Deliver continuous information to unit 5. The control unit 5 determines when the controllable valves 2, 3 should be opened or closed. The compressor shaft 11 is connected to, for example, an electric motor or a vehicle engine (the connection is not shown).

  The air supplied via the inlet valve 2 is preferably compressed, for example by an exhaust gas turbine of the vehicle. Advantageously, the compressed air is taken downstream of an intercooler (whose connection is not shown) that may be present in the vehicle. The outflow check valve 6 and the inflow check valve 13 equipped with the closing member 14 perform a support function. The closing member 14 is connected to the tank 8 via a conduit 15. If the pressure in the tank 8 decreases below a predetermined level, the closure member 14 opens, for example, by the action of a mechanical spring 16 so that air to be compressed is supplied via the inflow check valve 13. . This assist function means that the pressurized air can be reduced to a predetermined amount while the controllable inlet valve 2 is closed or disabled. This is important, for example, in order to be able to advance the vehicle at least in part by an air assist member for fuel injection or braking devices. For example, if the controllable valves 2, 3 are constituted by pneumatically actuated valves and the pressure in the tank 8 is too low to actuate the valves, the closure member associated with the inflow check valve 13 A support function is provided so that the pressure in the tank is sufficient for the operation of the valves 2 and 3 obtained by the spring 16 before 14 is closed.

  When the controllable valves 2, 3 are pneumatically operated valves, there is an air conduit (not shown) between the valves 2, 3 and the tank 8. For example, the pressurized air for the vehicle support device is taken out from the tank 8 through the connection portion 17. Only a small check valve 13, 6 is required for the described support function. The demand for high flow capacity is met by controllable valves 2,3. When the inflow check valve 13 is closed by the operation of the closing member 14 during the compression stroke, the outlet valve 3 is opened by a pressure balance between the air in the tank 8 and the air compressed in the cylinder 1. A sensor 18 operatively connected to the control unit 5 records the cylinder pressure. This pressure is compared with the pressure in the tank by the control unit to check that the outlet valve 3 has been operated at the correct angular position of the crank.

  According to another embodiment of the invention, the small check valve 6 and the controllable outlet valve 3 for the outflow are replaced with one or more outflow check valves. According to a further embodiment of the invention, the inflow check valve 13 and the controllable inlet valve 2 are replaced with a large inflow check valve. The closing member 14 is replaced by a rapidly controllable member that, like the valves 2 and 3, can block the air flow to be compressed in a short period of one cycle.

It is the schematic which illustrates the compressor provided with the piston.

Claims (11)

  The volume is expanded during the intake stroke, the gas introduction volume is compressed during the exhaust stroke, and the gas flow is driven by a compressor that is removed via an outlet check valve (6) and / or an operable outlet valve (3). A control method for controlling, wherein the compressor has a controllable inlet valve (2) that operates by air pressure, hydraulic pressure, or electromagnetic action and opens and closes based on a signal from a control device. The gas flow control method characterized in that the inlet valve (2) is closed during at least part of the intake stroke.   The gas flow control method according to claim 1, characterized in that the inlet valve (2) is closed during the entire intake stroke.   In order to deliver the required amount of compressed gas for the time being at a given number of revolutions per minute, the frequency of the cycle with the closed intake stroke is varied between 0% and 100% of the revolutions per minute. The gas flow control method according to claim 1 or 2, wherein   4. A gas flow control method according to claim 3, wherein equal rotation is performed between each cycle with a closed intake stroke or each successive series of cycles.   The gas flow control method according to any one of claims 1 to 4, wherein the inlet valve (2) is closed at or after the transition from the intake stroke to the exhaust stroke.   In addition to the controllable inlet valve (2), the inlet of the compressor (1) is provided with an inflow check valve (13), and a conduit for supplying gas to the latter is in the tank (8) associated with the compressor 6. A valve according to claim 1, characterized in that it is throttled or closed by a closing member (14) arranged near or upstream of the check valve by controlling the gas pressure of the check valve. Gas flow control method.   The gas flow control method according to claim 6, wherein the closing member (14) is a controllable valve and is opened and closed based on a signal from the control device.   Apart from the check valve for outflow (6), the outlet of the compressor (1) is operated by pneumatic, hydraulic or electromagnetic action and can be controlled to open and close based on a signal from the control device (3 The gas flow control method according to any one of claims 1 to 7, further comprising:   When there is a pressure equilibrium between the gas to be evacuated and the gas on the opposite side of the outlet valve (3), the outlet valve (3) is opened and the latter is recorded by another sensor (9). 9. A gas flow control method according to any one of claims 1 to 8, characterized in that it is controlled by a sensor (18) which records the cylinder pressure compared with the tank internal pressure.   A conduit (7) extending between said compressor (1) and said tank (8) satisfies the demand for pressurized gas between said compressor and equipment using pressurized gas. 10. The gas flow control method according to any one of 1 to 9.   A control device comprising a computer program suitable for carrying out the gas flow control method according to claim 1.

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