CN107664120B - Linear compressor top dead center detection method based on stroke judgment - Google Patents
Linear compressor top dead center detection method based on stroke judgment Download PDFInfo
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- CN107664120B CN107664120B CN201610596249.2A CN201610596249A CN107664120B CN 107664120 B CN107664120 B CN 107664120B CN 201610596249 A CN201610596249 A CN 201610596249A CN 107664120 B CN107664120 B CN 107664120B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B51/00—Testing machines, pumps, or pumping installations
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- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
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Abstract
The invention provides a linear compressor top dead center detection method based on stroke judgment, which gradually increases the piston stroke X of a linear compressor, the resonant frequency f of the linear compressor is changed along with the increase of the piston stroke X, and when the change trend of the resonant frequency f is changed, the linear compressor in the state reaches a top dead center state. The top dead center of the linear compressor can be accurately detected without adding a sensor, so that the operation efficiency and the reliability of the linear compressor are improved.
Description
Technical Field
The invention relates to a compressor, in particular to a linear compressor top dead center detection method based on stroke judgment.
Background
At present, the compressors used in the refrigeration equipment are of a rotary type and a linear type, and the linear compressor generally comprises a shell, a stator, a coil, a rotor, a piston, a cylinder, a spring rear baffle, a spring and other parts; wherein, a magnet is arranged on the rotor, the magnet is inserted in a magnetic field space formed by the stator, a coil is arranged in the stator, one end of the piston is connected on the rotor, and the other end of the piston is inserted in an inner cavity of the cylinder 6. In the using process, the coil is electrified to generate an alternating magnetic field to drive the rotor to drive the piston to reciprocate at a high frequency, after the linear compressor operates stably, the linear compressor works at a resonance frequency, the resonance frequency can also change under the condition that the operation parameters of the linear compressor are different, and the resonance frequency in different states can be easily obtained by a method for detecting the resonance frequency in the prior control technology. However, due to the limitation of the operation principle of the linear compressor, the efficiency of the linear compressor is not always increased linearly while the stroke of the piston of the linear compressor is increased, and since the effective stroke of the piston is constant, the efficiency of the linear compressor is the highest when the piston moves to the maximum stroke position during the reciprocating movement of the piston, and the maximum stroke position of the piston is usually the position of the piston moving to the cylinder closest to the exhaust valve, and is usually called Top Dead Center (TDC). In the prior art, there are various ways for judging the top dead center of the linear compressor during the operation process, for example: directly detecting the position of the piston by adopting a sensor (such as a displacement sensor, a pressure sensor, a vibration sensor and the like) to find the position of the upper dead center; or the position of the top dead center is found according to the change characteristics of the current or the voltage (such as the information of the change rate or the proportion of higher harmonic components). Aiming at the two schemes, the installation of the sensor can increase the cost of the compressor and reduce the running reliability of the compressor, the judgment is carried out according to the change of current or voltage, the signal filtering analysis operation is needed, and the signal distortion is easy to occur in the signal detection process to influence the detection accuracy. The invention aims to solve the technical problem of how to design a linear compressor top dead center detection method based on stroke judgment, which has low cost, reliable operation and higher detection accuracy.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for detecting the top dead center of the linear compressor based on the stroke judgment can accurately detect the top dead center of the linear compressor without adding a sensor, so that the operating efficiency and the reliability of the linear compressor are improved.
The invention provides a linear compressor top dead center detection method based on stroke judgment, which gradually increases the piston stroke X of a linear compressor, the resonant frequency f of the linear compressor changes along with the increase of the piston stroke X, and when the change trend of the resonant frequency f changes, the linear compressor in the state reaches a top dead center state.
Further, when the rate of change df/dX =0 of the resonant frequency of the linear compressor with the piston stroke, the linear compressor in this state reaches the top dead center state.
Further, when the resonance frequency of the linear compressor has an inflection point with respect to the secondary derivative of the piston stroke, the linear compressor in this state reaches the top dead center state.
Further, the initial stroke of the linear compressor is X0， X0Corresponding to an initial resonance frequency f0The stroke of the piston is increased by Δ X, and the stroke of the piston is X in the running staten= X0+n∆X， XnCorresponding operating state resonance frequency fnWherein n is more than or equal to 0; with XnIncrease of (2), corresponding to the resonance frequency fnChange when fnWhen the variation trend of the compressor is changed, the linear compressor in the state reaches a top dead center state; piston stroke X in determining top dead center conditionnAfter that, the linear compressor is controlled by XnOr Xn-1Is operated with a piston stroke, corresponding to a linear compressor at fnOr fn-1Is operated at the resonant frequency of (c).
Further, the piston stroke X satisfies the following equation:(ii) a Wherein X' is the movement speed of the piston, U (t) is the supply voltage of the linear compressor, I is the supply current of the linear compressor, R is the resistance of the linear compressor, L is the inductance of the linear compressor, c is the capacitance of the linear compressor,is the motor constant.
The invention also provides a linear compressor top dead center detection method based on stroke judgment, which gradually reduces the piston stroke X of the linear compressor, the resonant frequency f of the linear compressor changes along with the piston stroke X in the process of reducing the piston stroke X, and when the change trend of the resonant frequency f changes, the linear compressor in the state reaches the top dead center state.
Further, the initial stroke of the linear compressor is X0， X0Corresponding to an initial resonance frequency f0The stroke of the piston is reduced to X, and the stroke of the piston is X in the running staten= X0-n∆X， XnCorresponding operating state resonance frequency fnWherein n is more than or equal to 0; with XnIs reduced, corresponding to the resonance frequency fnChange when fnWhen the variation trend of the compressor is changed, the linear compressor in the state reaches a top dead center state; piston stroke X in determining top dead center conditionnAfter that, the linear compressor is controlled by XnOr Xn+1Is operated with a piston stroke, corresponding to a linear compressor at fnOr fn+1Is operated at the resonant frequency of (c).
The invention provides a linear compressor top dead center detection method based on stroke judgment, which can find the top dead center by analyzing the change of resonance frequency in the process of changing the stroke of a piston, can find the accurate position of the top dead center without depending on the detection of current or voltage, simultaneously, does not need to additionally add a sensor in the linear compressor to detect the position of the piston, utilizes the linear compressor to operate under the resonance frequency, takes the increase of the stroke of the piston as an example, in the process of increasing the stroke of the piston, the stroke of the piston is gradually increased, the corresponding resonance frequency is in a reduction trend, along with the continuous increase of the stroke of the piston, when the piston reaches the top dead center position, the resonance frequency is suddenly changed, the value of the resonance frequency is suddenly increased, thereby accurately judging the operation state of the top dead center of the linear compressor, after accurately finding the piston stroke corresponding to the top dead center, the linear compressor can be controlled to operate near the top dead center to ensure efficient operation of the linear compressor, and the top dead center of the linear compressor can be accurately detected without adding a sensor, so that the operating efficiency and the reliability of the linear compressor are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a graph illustrating a variation of a resonant frequency and a piston stroke in an embodiment of a method for detecting a top dead center of a linear compressor based on stroke determination according to the present invention;
FIG. 2 is a graph of the variation rate of the resonant frequency and the piston speed in an embodiment of the method for detecting the top dead center of the linear compressor based on the stroke judgment according to the present invention;
fig. 3 is a graph of variation of secondary derivation of resonant frequency and piston stroke in an embodiment of the method for detecting top dead center of a linear compressor based on stroke determination according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, in the operation of the linear compressor, as the stroke X of the piston changes regularly (continuously increases or continuously decreases), the resonant frequency f of the linear compressor will also change, and when the trend of the change of the resonant frequency f changes, it can be confirmed that the piston moves to the vicinity of the top dead center position. The following description will be given taking an example in which the piston stroke X is gradually increased.
The resonant frequency f of the linear compressor changes along with the increase of the piston stroke X, the piston stroke of the linear compressor becomes larger in the process of increasing the piston stroke X, meanwhile, the resonant frequency f changes in a gradually decreasing trend, when the piston moves to the top dead center position, the resonant frequency f changes in a suddenly increasing trend along with the continuous increase of the piston stroke X, and when the change trend of the resonant frequency f changes, the linear compressor in the state reaches the top dead center state. The above process is a process of scanning the top dead center, and according to the actual use condition, sometimes because of the operation condition of the linear compressor, the process of scanning the top dead center needs to be repeated several times, and according to the results of several times of scanning, the position of the top dead center is determined comprehensively, for example, the average value of several times of scanning results or the last scanning result is taken, or several times of scanning results are extracted for determination, and the like, and the selection can be performed according to the operation condition of the linear compressor.
Based on the technical scheme, the top dead center can be obtained in various modes according to the variation trend of the resonance frequency f. For example: as shown in fig. 2, when the rate of change df/dX =0 of the resonant frequency of the linear compressor with the piston stroke, the linear compressor in this state reaches the top dead center state; alternatively, as shown in fig. 3, when an inflection point occurs in a secondary derivative of the piston stroke with respect to the resonant frequency of the linear compressor, the linear compressor in this state reaches a top dead center state. The variation curve of the resonant frequency and the piston stroke is obtained by accumulating information through a controller of the linear compressor according to data information of the resonant frequency and the piston stroke in the process of finding the top dead center, and a specific mode is not limited. In addition, the adjustment mode of the piston stroke can be adjusted by changing the current or the voltage.
After the operating state parameters of the top dead center of the linear compressor are obtained through the mode, the piston of the linear compressor can be accurately controlled to move to the position near the top dead center, so that the efficiency of the compressor is improved. The specific operation process is as follows: initial stroke of the linear compressor is X0， X0Corresponding to an initial resonance frequency f0The stroke of the piston is increased by Δ X, and the stroke of the piston is X in the running staten= X0+n∆X， XnCorresponding operating state resonance frequency fnWherein n is more than or equal to 0; with XnIncrease of (2), corresponding to the resonance frequency fnChange when fnWhen the variation trend of the compressor is changed, the linear compressor in the state reaches a top dead center state; piston stroke X in determining top dead center conditionnAfter that, the linear compressor is controlled by XnOr Xn-1Is operated with a piston stroke, corresponding to a linear compressor at fnOr fn-1Is operated at the resonant frequency of (c).
Wherein the acquisition of the stroke X of the piston can be based on the formulaAnd (6) obtaining. Wherein X' is the movement speed of the piston, U (t) is the supply voltage of the linear compressor, I is the supply current of the linear compressor, R is the resistance of the linear compressor, L is the inductance of the linear compressor, c is the capacitance of the linear compressor,is the motor constant.
The invention provides a linear compressor top dead center detection method based on stroke judgment, which can find the top dead center by analyzing the change of resonance frequency in the process of piston stroke increase, can find the accurate position of the top dead center without depending on the detection of current or voltage, and simultaneously, does not need to additionally add a sensor in the linear compressor to detect the position of the piston, utilizes the linear compressor to operate under the resonance frequency, the stroke of the piston is gradually increased in the process of piston stroke increase, the corresponding resonance frequency is in a reduction trend, when the piston reaches the top dead center position along with the continuous increase of the piston stroke, the resonance frequency is suddenly changed, the value of the resonance frequency is suddenly increased, the top dead center operation state of the linear compressor is accurately judged in turn, and the linear compressor can be controlled to operate near the top dead center after the piston stroke corresponding to the top dead center is accurately found to ensure the efficient operation of the linear compressor, the top dead center of the linear compressor can be accurately detected without adding a sensor, so that the operation efficiency and the reliability of the linear compressor are improved.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (4)
1. A linear compressor top dead center detection method based on stroke judgment is characterized in that a piston stroke X of a linear compressor is gradually increased, a resonant frequency f of the linear compressor is changed along with the piston stroke X in the increasing process, and when the change trend of the resonant frequency f changes, the linear compressor in the state reaches a top dead center state, specifically:
when the change rate df/dX =0 of the resonant frequency of the linear compressor with the piston stroke, the linear compressor in this state reaches the top dead center state; or,
when the resonance frequency of the linear compressor generates an inflection point on the secondary derivative value of the piston stroke, the linear compressor in the state reaches the top dead center state.
2. The stroke judgment based top dead center detecting method of a linear compressor according to claim 1, wherein the initial stroke of the linear compressor is X0， X0Corresponding to an initial resonance frequency f0The stroke of the piston is increased by Δ X, and the stroke of the piston is X in the running staten= X0+n∆X， XnCorresponding operating state resonance frequency fnWherein n is more than or equal to 0; with XnIncrease of (2), corresponding to the resonance frequency fnChange when fnWhen the variation trend of the compressor is changed, the linear compressor in the state reaches a top dead center state; piston stroke X in determining top dead center conditionnAfter that, the linear compressor is controlled by XnOr Xn-1Is operated with a piston stroke, corresponding to a linear compressor at fnOr fn-1Is operated at the resonant frequency of (c).
3. The stroke judgment based top dead center detecting method of a linear compressor according to claim 1, wherein the piston stroke X satisfies the following formula:(ii) a Wherein X' is the movement speed of the piston, U (t) is the supply voltage of the linear compressor, I is the supply current of the linear compressorR is the resistance of the linear compressor, L is the inductance of the linear compressor, c is the capacitance of the linear compressor,is the motor constant.
4. A linear compressor top dead center detection method based on stroke judgment is characterized in that a piston stroke X of a linear compressor is gradually reduced, a resonant frequency f of the linear compressor is changed along with the piston stroke X in the process of reducing the piston stroke X, and when the change trend of the resonant frequency f is changed, the linear compressor in the state reaches a top dead center state, specifically:
initial stroke of the linear compressor is X0， X0Corresponding to an initial resonance frequency f0The stroke of the piston is reduced to X, and the stroke of the piston is X in the running staten= X0-n∆X， XnCorresponding operating state resonance frequency fnWherein n is more than or equal to 0; with XnIs reduced, corresponding to the resonance frequency fnChange when fnWhen the variation trend of the compressor is changed, the linear compressor in the state reaches a top dead center state; piston stroke X in determining top dead center conditionnAfter that, the linear compressor is controlled by XnOr Xn+1Is operated with a piston stroke, corresponding to a linear compressor at fnOr fn+1Is operated at the resonant frequency of (c).
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1437635A1 (en) * | 1987-02-02 | 1988-11-15 | Омский политехнический институт | Refrigerating gas machine |
| US5346368A (en) * | 1990-10-10 | 1994-09-13 | Schwing America, Inc. | Sludge flow measuring system |
| CN101065578A (en) * | 2004-10-01 | 2007-10-31 | 菲舍尔和佩克尔应用有限公司 | Linear compressor controller |
| CN101305512A (en) * | 2004-08-30 | 2008-11-12 | Lg电子株式会社 | Straight-line compressor |
| CN103547805A (en) * | 2011-03-15 | 2014-01-29 | 惠而浦股份公司 | Actuation system for a resonant linear compressor, method for actuating a resonant linear compressor, and resonant linear compressor |
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- 2016-07-27 CN CN201610596249.2A patent/CN107664120B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1437635A1 (en) * | 1987-02-02 | 1988-11-15 | Омский политехнический институт | Refrigerating gas machine |
| US5346368A (en) * | 1990-10-10 | 1994-09-13 | Schwing America, Inc. | Sludge flow measuring system |
| CN101305512A (en) * | 2004-08-30 | 2008-11-12 | Lg电子株式会社 | Straight-line compressor |
| CN101065578A (en) * | 2004-10-01 | 2007-10-31 | 菲舍尔和佩克尔应用有限公司 | Linear compressor controller |
| CN103547805A (en) * | 2011-03-15 | 2014-01-29 | 惠而浦股份公司 | Actuation system for a resonant linear compressor, method for actuating a resonant linear compressor, and resonant linear compressor |
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