US20060059931A1

US20060059931A1 - Binary control compressor system

Info

Publication number: US20060059931A1
Application number: US10/945,632
Authority: US
Inventors: Bart Petterson
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-20
Filing date: 2004-09-20
Publication date: 2006-03-23

Abstract

The invention is a control system for controlling compressors that are used to cool a building or a manufacturing process. The control system utilizes compressors of different sizes, including a series of compressors in which each compressor is double the size of the previous one. A control system chooses a possible combination of compressors to closely match the building or process cooling needs. The compressors are chosen so that the cooling capacity closely matches the building cooling needs, so that all of the compressors tend to run in a steady state fashion, and the comfort level of the building or the temperature stability of the process is increased.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to heating and cooling control systems, and more particularly to a control system for air conditioning compressors.
2. Background Information
Modern buildings are kept cool in the summer by an air conditioning system. The air conditioning system is sized according to the cooling needs of a building. This is typically expressed in tons, and the compressors that are used to cool the building are made to have sufficient capacity in tons in order to cool the building. This is typically accomplished by having a number of compressors that can be shut on and off. As the air condition load of the building increases, additional compressors are turned on until eventually all of the compressors that are available are turned on. One configuration of such a system might have four equally sized compressors. These compressors can be staged to give four different steps of capacity control. Thus, as the process load increases, additional compressors are turned on to equal or exceed the needed capacity.
The same principle applies in cooling systems for other applications, such as the cooling liquids in a process.
Another prior art strategy for matching compressor load to the process load of a building is to have individual compressors that have multiple steps of capacity control. In this way, one compressor may be turned on and then stepped up through its different capacities, until a second compressor needs to be turned on in addition to the first. The disadvantage with this type of compressor is that it is very expensive in the initial costs to purchase and install the compressors. The installation is very complex, and the operation of the compressors are typically much more noisy than usual. When repairs are required they tend to be much more expensive than simpler installations. Another disadvantage with this type of system is that if one compressor goes off service, the system may be seriously impacted and would not have a backup capacity.
Another prior art type of control system is when compressors are used that have a variable speed drive that varies the compressor speed. This serves to modulate the compressor capacity. In this way a system can still have four compressors, but they would have a speed control that allows each compressor to be graduated in its output. Thus the first compressor could be turned on and gradually increased in its speed until its maximum capacity was exceeded. Then a second compressor would be turned on and ramped up to its maximum capacity. Another configuration of this type of system would be to have one large compressor with sufficient capacity to cool the entire building with a speed control for controlling the output of the compressor.
The disadvantages with this type of system are similar to the disadvantages described above. The initial installation is much more expensive than with a simpler compressor. This system is complex, noisy and more expensive to repair. Additionally, if the one single compressor went out, the system would be totally shut down. If the system had multiple compressors and one of them went down, the system would be greatly impacted.
Therefore what is needed is a compressor system that is inexpensive to install and has great flexibility. It is desirable that the system be able to closely match the cooling needs of a building or of a processing system, and to exceed the cooling needs there only need be a small amount or none at all. The system should have the ability to compensate for the loss of a compressor so that cooling can continue without that compressor. Also, the system should be simple and uncomplicated as well as inexpensive to install.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

SUMMARY OF THE INVENTION

These shortcomings are addressed by the control system of the invention. The compressor system of the invention is a graduated system that may be also configured to be binary. The system is designed to have a number of compressors, starting with at least two for a simple system, to multiple compressors such as four, five or more. A graduated compressor system logic module is used for controlling these compressors in operating air conditioning and process cooling systems. The main feature of the compressors of the system is that they are selected to have graduated output capacity. Included in the compressor management system is a temperature sensing system for determining the cooling needs of the building or process. Another part of the system is a control logic system that contains information about the compressor capacity of each of the compressors of the system. The control logic compares the cooling needs of the building, which is input from the temperature sensing system, with the compressors of the system and all of the possible permutations of combining them in order to find a compressor configuration that meets the cooling needs of the building at that time. The control logic system is able to combine the potential capacities of the multiple compressors to arrive at a greater number of system capacities than there are compressors. For instance, in a two-compressor system, one compressor might be a ten-ton compressor and the second one might be a twenty-ton compressor. By combining the capacities of the compressors, a system with ten, twenty or thirty tons is available. When the system includes more compressors, such as four or five, a much larger number of combinations are possible. This allows the system to meet the needs of the building, but not to exceed it greatly. This saves energy by not over cooling the building, and then having the system shut down for a period of time or cycle compressors offline. Thus, the compressors are more likely to run in a steady state fashion, with compressors being switched on and off as the building load gradually increases. Compressor cycling is substantially decreased which extends compressor life.
For this system to work optimally, the compressors are of different sizes. One configuration for the compressors is for them to be approximately double in size. Thus, a first compressor could be rated at two tons, a second compressor could be rated at approximately four tons, a third compressor could be rated at approximately eight tons and so on.
If a compressor system includes two compressors, then there are a possible three system capacity combinations, which would be compressor 1, compressor 2 and compressor 1+2. In a system that has five compressors, it can be seen that there are a large number of possible compressor combinations, and thus the system is able to match the building or process needs fairly closely. In a six-compressor system there are up to 63 possible combinations of those six compressors. This compares to the six possible combinations of a prior art system with six compressors in which all the compressors are approximately the same size.
The system is also a method of cooling a building using the graduated compressor system described above. The method includes the step of sensing temperatures within the building utilizing a temperature sensing system. The next step is providing a number of compressors of graduated output capacities for use in cooling the building, with each of the compressors in a range of increasing capacity. The next step is determining whether the temperatures exceed a target temperature. The next step is supplying cooled air or liquid to the building or process when the building temperatures exceed the target temperature, by using a control logic system. The control logic system is connected to the compressors, with each compressor having graduated output capacities. The control logic system compares the cooling needs of the building with the available compressor capacity, and the possible combinations of the capacities of the compressors, and selects a compressor or a combination of compressors whose combined capacities substantially match the cooling needs of the building. The next step is activating the selected compressor or the combination of compressors.
The purpose of the foregoing Abstract is to enable the United States Patent and Trademark Office and the public generally, and especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection, the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description wherein I have shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiment are to be regarded as illustrative in nature, and not as restrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a table showing a prior art system output in response to building needs.
FIG. 2 is a table showing a prior art system output in response to building needs.
FIG. 3 is a table showing the system of the invention's output in response to building needs.
FIG. 4 is a table showing the system of the invention's output in response to building needs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
The air conditioning control system of the invention can take many configurations depending on the building size and the cooling needs. However, one example is illustrated in some detail here, in order to illustrate the preferred embodiment of the invention. In one version of the preferred embodiment, the control system of the invention is comprised of six compressors, each with a different and increasing capacity. In this example, the compressors are designated as compressors A, B, C, D, E and F. The capacity of the compressors A-F is shown in the table below.

Compressor Capacity in Tons

A 5

B 10

C 15

D 20

E 25

F 30
A second preferred embodiment is one in which the compressors are roughly double the capacity of the previous compressor. The capacities of a system such as this would be as follows:

Compressor Capacity in Tons

A 2

B 4

C 8

D 16

E 32

F 64
The broad innovative concept of this system is that the capacities are of different size, which is different than the control scheme and compressor sizing that is utilized currently in most buildings. An array of compressors that is not exactly double the previous compressor, or which includes one or more compressors that are the same size as another compressor in the array, is still within the concept of the present invention. The table below shows that the system above can have 63 possible combinations, and the graph below shows the possible output curve of these six compressors. As can be seen, a building or process cooling need can be closely matched with this system.
This system presents advantages to several of the prior art methods of operating and staging compressors. One of the prior art methods is to have multiple compressors, such as four compressors, that are generally equal sized and can be staged to give four steps of capacity control. Thus, if the maximum load of a building were 105 tons, then the four compressors that could handle this load would each have to have a capacity of 27 tons. Thus as the building cooling requirements increased from 0 to 105 tons, the compressors would be switched on one at a time until they reach their maximum, with all four compressors being switched on. One of the compressors would need to be cycled on and off most of the time to approximately match the building load. An example of this type of compressor staging is shown in FIG. 1.
FIG. 1 shows a graph of varying building cooling needs. As the building cooling needs change, 1, 2, 3 or 4 of the four compressors of this system would be switched on and off. They are required to meet the cooling needs of the building, and the less they exceed the cooling needs of the building the more efficient the system is. As can be seen in FIG. 2, a system of this sort exceeds the cooling needs of the building, sometimes by quite a large amount. When this happens, the last compressor switches off when the building has cooled down and then switches on again when it heats up. This results in the marginal compressor turning on and off a lot, which reduces the life of the compressor and leads to higher replacement and maintenance costs, and lower comfort levels.
This is contrasted with a compressor system of the present invention in which six compressors are present, with the six compressors having a total maximum load of 105 tons. These compressors could be turned on one at a time or in combinations to match the cooling needs of the building. FIG. 3 shows the building needs compared with the cooling capacity that is possible when the capacities of these six compressors are combined.
FIG. 4 shows the amount that the system output exceeded the building demand. As can be seen, the system of the invention was able to more closely match the building needs. The result of this would be that the system that is depicted in FIGS. 3 and 4 would tend to run in a steady state of operation, with an occasional compressor being turned on and off to meet the changing needs of the building. This would also mean that the air conditioning would run at a continual rate, which almost exactly matches the building cooling needs, rather than shutting on and off.
While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a plurality of compressors of graduated output capacities, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building; and

a control logic system, containing information about comparative compressor capacity; wherein said control logic system compares the cooling needs of said building with the available compressor capacity, and selects a compressor or combination of compressors with combined capacities which substantially match the current cooling need of a building.

2. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, in which each of said compressors is approximately double the capacity of the next smaller compressor, in which a first compressor with a capacity of A, will be followed by a second compressor with a capacity of approximately 2 A, and a third compressor with a capacity of approximately 4 A, and so on with each compressor in the series having approximately double the capacity of the previous compressor.

3. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, in which said compressors are in a generally capacity doubling configuration, in which a first compressor with a capacity of A, will be followed by a second compressor with a capacity of 2 A, and a third compressor with a capacity of 4 A, and so on with each compressor in the series having approximately double the capacity of the previous compressor.

4. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, which comprises two compressors.

5. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a first compressor, with a pre-selected capacity, for providing air conditioning to a building;

a second compressor, with a larger capacity of said first compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

a control logic system, containing information about compressor capacity; wherein said control logic system compares the cooling needs of said building with the available compressor capacity, and selects a compressor or a combination of compressors with combined capacities which match the current cooling need of a building.

6. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a first compressor, with a preselected capacity, for providing air conditioning to a building;

a second compressor, roughly double the capacity of said first compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

7. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, which comprises three compressors.

8. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a second compressor, with a larger capacity than said first compressor, for providing air conditioning to a building;

a third compressor, with a larger capacity than said second compressor, for providing air conditioning to a building:

a temperature sensing system, for determining the cooling needs of a building;

9. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a third compressor, roughly double the capacity of said second compressor, for providing air conditioning to a building:

a temperature sensing system, for determining the cooling needs of a building;

10. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, which comprises four compressors.

11. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a second compressor, with a capacity larger than the capacity of said first compressor, for providing air conditioning to a building;

a third compressor, with a capacity larger than the capacity of said second compressor for providing air conditioning to a building:

a fourth compressor, with a capacity larger than the capacity of said third compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

12. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a fourth compressor, roughly double the capacity of said third compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

13. The graduated compressor system for use in building air conditioning management and process cooling of claim 1, which comprises five compressors.

14. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a fifth compressor, with a capacity larger than the capacity of said fourth compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

15. A graduated compressor system for use in building air conditioning management and process cooling, comprising:

a fifth compressor, roughly double the capacity of said fourth compressor, for providing air conditioning to a building;

a temperature sensing system, for determining the cooling needs of a building;

16. A method of cooling a building using a graduated compressor system comprising:

sensing temperatures within said building or process equipment, utilizing a temperature sensing system;

providing a plurality of compressors of graduated output capacities, for cooling said building, with each of said compressors in a range of increasing capacity;

determining whether said temperatures exceed a target temperature;

supplying cooled air to said building, when temperatures exceed a target temperature, using a control logic system connected to said plurality of compressors of graduated output capacities, wherein said control logic system compares the cooling needs of said building with the available compressor capacity, and selects a compressor or a combination of said plurality of compressors with combined capacities which substantially match the current cooling need of a building activating said compressor or said combination of compressors.

17. The method of claim 16 wherein said plurality of compressors approximately double in size from one compressor to another.