JP2011149322A - Capacity detector for variable displacement compressor, and variable displacement compressor provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacity detector for a variable displacement compressor and the variable displacement compressor provided with the same, using a piston having the high degree of freedom in the shape of a detected surface and not requiring machining accuracy, resistant to disturbance, and estimating capacity. <P>SOLUTION: This capacity detector for the variable displacement compressor includes: a position detection sensor provided on the lateral side of the piston and outputting the displacement signal of the detected surface of the piston when the piston reciprocates; and an estimation means measuring and storing the waveform pattern (A) of the displacement signal for one stroke of the piston during an operation with the maximum capacity, detecting the waveform pattern (B) of the displacement signal for one stroke of the piston during the present operation, and estimating capacity during the present operation corresponding to the stroke of the piston during the present operation from the comparison of the waveform pattern (A) with the waveform pattern (B). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable displacement compressor capable of changing a discharge capacity by changing a stroke of a piston, and more particularly to a capacity detection that can be appropriately applied to a variable displacement compressor to detect the capacity of the compressor. Relates to the device.

  2. Description of the Related Art Generally, a variable capacity compressor capable of variably controlling a discharge capacity (hereinafter sometimes simply referred to as “compressor”) is known as a compressor used in a vehicle air conditioner or the like. In this type of compressor in a piston type compressor, for example, a swash plate that can be inclined with respect to a drive shaft is housed in a crank chamber. As the crank chamber pressure increases, the swash plate approaches a right angle to the axis of the drive shaft (the inclination angle of the swash plate decreases). On the other hand, when the crank chamber pressure decreases, the axis of the drive shaft The swash plate is inclined so as to approach (so that the inclination angle of the swash plate increases). The stroke of the piston provided in the compressor changes according to the inclination state of the swash plate. For example, when the crank chamber pressure is high and the tilt angle of the swash plate is small, the piston stroke is small. Conversely, when the crank chamber pressure is low and the tilt angle of the swash plate is large, the piston stroke is large. . Therefore, the discharge capacity decreases as the piston stroke decreases, and the discharge capacity increases as the stroke increases.

  In such a variable capacity compressor, it is required to grasp the capacity of the compressor during the current operation in order to control the compressor itself and the refrigeration circuit of the air conditioner in which the compressor is used. There are many cases. In the prior art disclosed in Patent Document 1, a detected surface that is tapered in the axial direction is formed on the piston. A non-contact type position detection sensor is arranged on the side of the piston so as to face the detection surface. The position detection sensor detects a distance between a detected surface (detection target point) that is approached and separated by a stroke change of the piston and the position detection sensor. The air conditioning ECU detects the stroke of the piston based on the detection distance information from the position detection sensor, and grasps the capacity of the compressor based on the detected stroke.

JP 2003-148357 A

However, as described in Patent Document 1, in the method of obtaining the discharge capacity from the distance between the detection surface (detection target point) that approaches and separates due to the stroke change of the piston, the piston shape is greatly restricted, There are the following problems. For example,
・ It is necessary to accurately create a taper shape or step shape on the back of the piston neck that will be the surface to be detected, which increases costs.
-Even in the case of forming the most realistic monotonously increasing (or monotonically decreasing) tapered shape, the thickness of the piston neck becomes thick and the weight increases.

Also, when calculating the capacity from the distance between the detected surface and the position detection sensor,
・ If foreign matter passes between the sensor and the surface to be detected, or if wear or scratches occur on the surface to be detected, the effect is reflected in the calculated discharge volume as it is and becomes an abnormal value. weak.
・ If the play between the piston and cylinder bore is large, the distance to the surface to be detected will change if the operating conditions are different even with the same piston stroke. This change in distance leads to a detection error and thus a capacitance calculation error. Further, when the distance between the detection surface and the position detection sensor changes depending on the temperature or the detection sensitivity changes depending on the temperature, a problem of temperature drift occurs regarding the calculation of the capacity.

  Therefore, the object of the present invention is to focus on the problems as described above, and can use a piston that has a remarkably high degree of freedom in shape on the surface to be detected and does not require machining accuracy, as compared to the prior art, and Capacitance detection of a variable displacement compressor that is less affected even if the detection surface is worn or scratched, or the detection signal changes due to the clearance between the piston and cylinder bore, and can estimate the capacity against disturbances. The present invention provides an apparatus and a variable displacement compressor including the apparatus.

In order to solve the above-described problems, a capacity detection device for a variable capacity compressor according to the present invention is a variable capacity type capable of performing gas compression by reciprocating movement of a piston and changing the capacity by changing the stroke of the piston. A compressor capacity detection device comprising:
(1) A position detection sensor disposed on the side of the piston, the shape of the piston being laterally moved in front of the position detection sensor by a reciprocating motion of the piston being a detection surface, A position detection sensor that outputs a displacement signal that approaches and moves away from the position detection sensor when a detection target point that is a part facing the position detection sensor is reciprocating a piston;
(2) The waveform pattern (A) of the displacement signal for one stroke of the piston during the maximum capacity operation is measured and stored, and the waveform pattern (B) of the displacement signal for the piston stroke of the current operation is detected. Estimating means for estimating a capacity during current operation corresponding to a piston stroke during current operation from a comparison between the waveform pattern (A) and the waveform pattern (B);
It consists of what is characterized by having.

  In such a capacity detection device according to the present invention, the position detection sensor is arranged on the side of the piston, and the front side of the position detection sensor by the reciprocation of the piston (the direction in which the position detection sensor performs distance measurement). The side surface shape portion of the piston that is laterally moved is set as the detection surface. Therefore, the detection target point, which is a part facing the position detection sensor on the detected surface, is sequentially changed on the detected surface in accordance with the reciprocating motion of the piston. The position detection sensor is configured to output a displacement signal that moves closer and away as a waveform pattern so that the detection target point moves closer to and away from the position detection sensor due to a change in the stroke of the piston. Therefore, by outputting the displacement signal during one piston stroke, it is possible to obtain the entire waveform pattern of the detected displacement signal of the entire piston one stroke from the top dead center to the bottom dead center at that time. It can be considered that the waveform pattern of the displacement signal for one stroke of the piston corresponds to the capacity of the compressor at that time. The present invention is premised on the correspondence between the waveform pattern of the displacement signal and the capacity of the compressor, and the displacement signal waveform pattern (A) for one stroke of the piston obtained at the maximum capacity operation is the piston 1 at the other capacity operation. This utilizes the fact that the displacement signal waveform pattern (B) for the stroke is completely included. That is, the estimation means measures and stores the waveform pattern (A) of the displacement signal for one stroke of the piston at the maximum capacity operation, and stores the waveform pattern (B) of the displacement signal for one stroke of the piston at the current operation. By detecting and comparing the stored waveform pattern (A) with the detected waveform pattern (B), that is, to understand to what part of the waveform pattern (A) the waveform pattern (B) corresponds Thereby, the ratio of the piston one stroke at the current operation to the piston one stroke at the maximum capacity operation is grasped, and the capacity at the current operation corresponding to the piston stroke at the current operation is estimated. The shape of the back of the piston that forms the surface to be detected has a complex shape across the head, neck, and cylinder, so the detection signal pattern obtained during stroke operation for each discharge capacity is sufficiently varied. It becomes. However, when the above-described capacity estimation method in the present invention is used, for example, as described in Patent Document 1 described above, it is necessary to accurately create the detection surface formed on the piston so as to correspond one-to-one with the discharge capacity. Absent. Therefore, the degree of freedom of the shape of the piston portion serving as the detection surface of the capacity detection device is increased, and it is possible to form a lighter and easier-to-make shape that does not cost. Further, in the structure of Patent Document 1, when a foreign object passes between the position detection sensor and the detection surface, or when wear or scratches occur on the detection surface, the influence is directly calculated on the discharge capacity. Since it is highly likely to be reflected and become an abnormal value, it is extremely vulnerable to disturbances. However, in the present invention, since the detection waveform pattern for the entire stroke of the piston is used for judgment, the detected surface is worn or scratched, the passage of foreign matter, etc. It is not easily affected by noise and is resistant to disturbances. Therefore, it is possible to accurately estimate the compressor capacity at that time with high accuracy.

  In the capacity detection device according to the present invention, the displacement signal waveform pattern (A) for one stroke of the piston during the maximum capacity operation and the displacement signal waveform pattern (B) for one stroke of the piston during the current operation are accurately determined. In order to grasp as a waveform pattern for one stroke of the piston, the estimation means uses the waveform pattern (A) and the waveform as a signal of a period of one rotation of the compressor or a top dead center signal of the piston. It can be used as a reference for the comparison of the pattern (B), and the capacity during the current operation can be estimated by the comparison. It is possible to recognize half the cycle of one rotation of the compressor as a cycle for one piston stroke, and from the top dead center signal of the piston, it is possible to accurately grasp from which timing the piston one stroke starts.

  In the capacity detection apparatus according to the present invention, the following various techniques can be employed as the compressor capacity estimation technique in the estimation means. For example, the estimation means compares a plurality of waveform patterns cut out from the waveform pattern (A) at a predetermined step rate with the waveform pattern (B), calculates a cross-correlation coefficient between them, The capacity when the cross-correlation coefficient shows the maximum value can be set as the estimated capacity during the current operation. By setting the capacity when the cross-correlation coefficient is the highest as the estimated capacity during the current operation, the capacity during the current operation can be estimated more accurately. For example, the detection signal pattern of the waveform pattern (B) to be searched is compared with the capacitance signal pattern obtained by cutting out the waveform pattern (A) every time the capacity pattern is 0% to 100%. Calculate the number of relationships. Among them, the capacity of the pattern having the highest cross-correlation coefficient is the estimated capacity for the detection signal pattern to be searched. A specific calculation formula of the cross correlation coefficient will be described later.

  Further, for example, the estimation means compares a plurality of waveform patterns cut out from the waveform pattern (A) at a predetermined step rate with the waveform pattern (B), and accumulates the residual sum between the two. And the capacity when the cumulative sum of the residuals shows the minimum value can be used as the estimated capacity during the current operation. By setting the capacity when the cumulative sum of residuals is the smallest as the estimated capacity during the current operation, the capacity during the current operation can be estimated more accurately. For example, the detection signal pattern of the waveform pattern (B) to be searched is compared with the capacitance signal pattern obtained by cutting out the waveform pattern (A) in units of 0% to 100%, and the residual Calculate the cumulative sum of. Among them, the capacity of the pattern having the smallest accumulated residual is the estimated capacity for the detection signal pattern to be searched. A specific arithmetic expression of the cumulative sum of residuals will be described later.

  Further, for example, the estimation means calculates a cumulative sum of differences between the deviation between the waveform pattern (A) and the average value thereof, and the deviation between the waveform pattern (B) and the average value thereof. The capacity when the cumulative sum of the differences shows the minimum value can also be used as the estimated capacity during the current operation. In actual operation of the compressor, the ambient temperature of the compressor including the sensor varies greatly depending on the operating environment and operating conditions. Therefore, if the sensor sensitivity / output has temperature dependency, it will be affected. Even when the waveform pattern (A) and the ambient environment temperature when the waveform pattern (B) are acquired are greatly different, even if the shape of the waveform pattern is the same, the absolute value is greatly different due to the influence of temperature drift. The level of the residual that is going to be found will change. However, when evaluated by the cumulative sum of the differences between the average values of the detection signal patterns (A) and (B) in that state, the influence of such an operating state is offset, and more accurately and quickly. The fitness can be calculated. An arithmetic expression for the cumulative sum of the deviations from the average value will be described later.

  When estimating the capacity during current operation based on the cumulative sum of residuals or the cumulative sum of deviations, the estimation means stops the calculation when the minimum value is exceeded while the cumulative sum is being calculated. When the calculation ends, the minimum value can be updated when the previous minimum value is not reached. If the minimum value is exceeded during the calculation of the cumulative sum, the minimum value is already known, so no further calculation is necessary, and the calculation is stopped by stopping the calculation at that time. Total time can be shortened. Further, when the minimum value of the obtained cumulative sum falls below the previous minimum value, it is possible to output the capacity during the current operation more accurately and accurately by updating the minimum value. More specifically, for example, in the calculation of the cumulative sum as described above, the degree of compatibility with the detection signal pattern is calculated for every step from 0 to 100% in all cycles, and the discharge capacity is calculated in real time. Attempting to do so increases the amount of computation and requires a CPU capable of high-speed computation, which may be a major obstacle to practical use, and a reduction in the amount of computation is required. Therefore, the above method is a method that significantly reduces the amount of calculation of the above-described fitness calculation and enables real-time measurement. Since the calculation is stopped when the minimum value is exceeded, the accuracy of the fitness calculation for searching for the minimum value does not decrease.

  In the estimation of the capacity during the current operation by the estimation means, if it is considered that an appropriate estimated value exists between the estimated values separated from each other, the capacity during the current operation can be estimated more accurately by interpolation. It is. That is, the estimation means interpolates a capacity area between the estimated capacity value indicating the maximum cross-correlation coefficient or the minimum cumulative sum and the calculated capacity values before and after the estimated capacity value, and within the interpolation area, If there is a value that is larger than the calculated cross-correlation coefficient or smaller than the cumulative sum calculated so far, that value can be used as the estimated capacity during the current operation. That is, as described above, for example, the detection signal pattern of the waveform pattern (B) to be searched for and the capacitance signal pattern obtained by cutting out the waveform pattern (A) at every step from the capacity 0% to 100%. When making comparisons one after another, if the interval is widened (for example, every 1%) and estimation is performed, the calculation time is short, but the estimation accuracy deteriorates. Conversely, if the step is shortened (for example, every 0.1%), the calculation time becomes longer, but the accuracy is improved. In other words, there is a trade-off relationship. Therefore, this interpolation method can be used in order to improve accuracy without taking calculation time. For example, it is a method of approximating with a certain function using several points near the capacity with the highest fitness and updating the extreme value of the approximate curve to a value with the highest fitness. The approximate curve may be approximated by a function having extreme values. For example, a spline curve, a high-order least square method, or the like can be adopted. However, the interpolation may be performed by any general method, and an example of the specific method will be described later.

  The signal of the above-mentioned period of one rotation of the compressor is obtained from the rotation signal of the compressor drive source, for example. The above-described piston top dead center signal is, for example, a part corresponding to the piston top dead center of a compressor driving rotating body (for example, a driving force transmission pulley, a driving unit such as a clutch or a torque limiter). To be detected, and detection means provided at a position facing the detected object. What is necessary is just to estimate the capacity | capacitance at the time of the present driving | operation of a compressor from these signals and the detection signal pattern from a position detection sensor.

  In the present invention, the waveform patterns (A) and (B) of the displacement signal for one stroke of the piston need only be compared. The waveform pattern of the displacement signal for one stroke of the piston is obtained when the piston reciprocates. The waveform patterns for one cycle of the compressor (the reciprocating motion of the piston) can be compared with each other. That is, the detection signal pattern for one cycle of the compressor is symmetric at the top dead center and the bottom dead center, and the capacity during the current operation can be calculated even with the detection signal pattern for one cycle. By comparing the detection signal patterns of one period, the information amount of the signal pattern increases, so that it is possible to improve the accuracy of searching for the degree of matching described above.

  In the present invention, as the position detection sensor, for example, a sensor that detects at least one of the uneven shape distribution, the electromagnetic characteristic distribution, and the light reflection characteristic distribution on the detection surface of the piston can be used. In any case, the signal obtained from the position detection sensor is varied in order to accurately estimate the capacity during the current operation over a wide range from 0% to 100% of the waveform pattern (A). Preferably.

  As such a position detection sensor, for example, an eddy current sensor, an electromagnetic induction sensor, a capacitance sensor, or a photoelectric reflection sensor is preferably used in terms of ensuring a clear signal waveform.

  For example, when an electromagnetic induction type sensor is used as the position detection sensor, a configuration in which paint or the like having magnetic properties is applied to the detection surface of the piston or a magnet is embedded is adopted. can do. In other words, it has a configuration in which the surface to be detected has a magnetic property by applying paint or resin mixed with metal powder having magnetic properties, plating, or embedding a magnet in the surface to be detected. is there.

  In addition, when a photoelectric reflection type sensor is used as the position detection sensor, in order to obtain a clearer detection signal, a configuration in which a paint having optical characteristics is applied to the detection surface of the piston is used. Can be adopted.

  Further, in the present invention, the estimation means is configured so that the waveform pattern (A) in the state is detected even when the detection signal from the position detection sensor changes from the initial value due to scratches, wear, etc. on the detected surface of the piston. By re-recording, it is possible to correct the influence of the change and estimate the capacity during the current operation. For example, even if the distribution shape of the reflective medium with high definition changes from the detected surface with respect to the initial value due to scratches, wear, etc., the detection signal pattern obtained at the maximum capacity operation in that state is acquired again. As a result, the influence of the change in the distribution pattern of the reflection medium can be corrected, and the accuracy at the time of deterioration can be improved. The acquisition of the detection signal pattern obtained during the maximum capacity operation is not particularly required to stop or remove the compressor, and can be acquired during the operation and can be easily performed.

  The present invention also provides a variable capacity compressor provided with the capacity detection device as described above. In such a compressor, it is possible to estimate the torque of the compressor from the estimated capacity and at least the discharge pressure and suction pressure of the compressor. It is also possible to control the valve opening of the capacity control valve that varies the capacity of the compressor using the estimated capacity as input information.

  As described above, according to the variable capacity compressor and the capacity detection device thereof according to the present invention, the shape and structure of the detected surface of the piston are more flexible than those of the prior art disclosed in Patent Document 1 described above. The degree of machining can be greatly increased, and high precision is not required for the processing of the piston, and the cost can be greatly reduced. In addition, even if the detection surface is worn or scratched, or when the detection signal changes due to the clearance between the piston and cylinder bore, it is possible to minimize the effect and to withstand disturbances. The estimation can be performed accurately.

It is a longitudinal section of a variable capacity type compressor provided with a capacity detection device concerning one embodiment of the present invention. It is explanatory drawing which shows the example of 1 method of capacity | capacitance estimation in the capacity | capacitance detection apparatus which concerns on this invention. It is a control flowchart which shows the example of 1 method of capacity | capacitance estimation in the capacity | capacitance detection apparatus which concerns on this invention. It is a relationship diagram between the cumulative sum of residuals and the number of processed data, showing an example of a method for iterative processing calculation at the time of capacity estimation in the capacity detection device according to the present invention. It is explanatory drawing which shows the example of 1 method of the interpolation process at the time of the capacity | capacitance estimation in the capacity | capacitance detection apparatus which concerns on this invention.

Hereinafter, an embodiment in which the present invention is embodied in a capacity detection device for a swash plate type variable displacement compressor used in a vehicle air conditioner will be described.
FIG. 1 shows a variable capacity compressor 1 provided with a capacity detection device 2 according to an embodiment of the present invention, and shows a longitudinal section of the compressor 1 at a minimum capacity. First, the variable capacity compressor 1 will be described. A rotational driving force from an external driving source is transmitted to a pulley 3 via a belt or the like, and from there to a driving shaft 5 of the compressor via a torque limiter mechanism 4. Communicated. In the crank chamber 8 formed by the front housing 6 and the cylinder block 7, a rotor 9 that is rotated integrally with the drive shaft 5 is connected to the rotor 9 via a link mechanism 10, and an inclination angle with respect to the drive shaft 5 is set. A variable swash plate 11 is provided, and the swash plate 11 is rotated in synchronization with the drive shaft 5. The cylinder block 7 is provided with a plurality of cylinder bores 12 (only one cylinder is shown), and a piston 13 is inserted into each cylinder bore 12 so as to be reciprocally movable. One end portion 13 a (neck portion) of the piston 13 is connected to the swash plate 11 via a pair of shoes 14 that are in sliding contact with both side surfaces of the swash plate 11. Converted. The stroke of the reciprocating motion of the piston 13 is varied in accordance with the inclination angle of the swash plate 11, and the inclination angle of the swash plate 11 is changed according to the pressure in the crank chamber 8, for example, as described above. In accordance with the reciprocating motion of the piston 13, a fluid to be compressed (for example, refrigerant) is sucked into the cylinder bore 12 from the suction chamber 16 formed in the cylinder head 15, and the compressed fluid compressed in the cylinder bore 12 is discharged into the discharge chamber. 17 is discharged to an external circuit.

  In such a variable displacement compressor 1, the discharge capacity depends on the displacement of the piston 13, that is, depends on the stroke of the piston 13. The capacity detection device 2 according to the present invention estimates the capacity during the current operation corresponding to the stroke of the piston 13 and is configured as follows, for example.

  That is, in the plurality of pistons 13 shown in FIG. 1, the back surface of one piston 13 becomes the detected surface 21. The shape of the detected surface 21 is set so that the distance between the detected surface 21 and the position detection sensor described below changes when the piston 13 reciprocates in one cycle. Since the above-described back surface of the piston 13 used in a normal swash plate type variable capacity compressor is the back surface of the head, neck, and cylindrical portion, the distance between the detected surface 21 and the position detection sensor is sufficiently clear. Continue to change. As the locus of the detection signal obtained during each discharge capacity operation is more varied, the accuracy of estimation is improved, so a slit or the like is provided so that the detected surface 21 is more varied with respect to the direction of reciprocation. In some cases. However, even in that case, it is not necessary to specify accuracy or shape. The detected surface 21 is disposed on the opposite side of the drive shaft 5 around the axis S so that a part of the detected surface 21 faces the inner peripheral surface 6 a of the front housing 6.

  On the inner peripheral surface 6a of the front housing 6, on the outer peripheral side of the neck portion 13a of the piston 13, that is, on the side of the neck portion 13a, the detection by the non-contact type position detection sensor 22 is made to face the detection surface 21 of the piston 13. A head 22a is disposed. For example, an eddy current loss detection type sensor is used as the position detection sensor 22.

  When the piston 13 is reciprocated, the detected surface 21 is the front side of the position detection sensor 22 (detection head 22a) (the direction side in which the detection head 22a performs distance measurement), and is merely a positional relationship on the drawing. If it is expressed as, it will be moved horizontally. Therefore, the detection target point K, which is a part facing the detection head 22a on the detected surface 21, sequentially changes along the shape on the detected surface 21 in accordance with the reciprocating motion of the piston 13, and this detection target point K And the distance L between the detection head 22a changes. The position detection sensor 22 detects the distance L between the detection head 22a and the detected surface 21 (detection target point K), and outputs this detection distance information L from the controller 23 to the air conditioner ECU 24.

  The air conditioner ECU 24 is a computer-like electronic control unit that estimates and grasps the discharge capacity of the compressor based on the detection distance information L from the position detection sensor 22. That is, the air conditioner ECU 24 constitutes capacity estimation means. The air conditioner ECU 24 transmits the grasped compressor capacity information to an engine ECU (not shown). Therefore, for example, the engine idling control by the engine ECU can be made suitable in consideration of the load torque of the compressor and the like.

  As described above, in one reciprocation of the piston 13, the detected surface 21 is operated so that the distance L between the detected head 22a and the displacement of the detected surface 21 is detected by the detecting head 22a. A displacement signal is output from the position detection sensor 22. As shown in FIG. 2, the displacement signal is a waveform pattern displacement signal while the piston 13 is moved between the top dead center position and the bottom dead center position, that is, for one stroke of the piston 13. The position detection sensor 22 outputs to the air conditioner ECU 24. The detection signal pattern of the distance information L (the waveform pattern of the displacement signal) varies depending on the operation of each discharge capacity.

  In this embodiment, for example, three pieces of information are required for detecting the discharge capacity. The first is a detection signal pattern (displacement signal waveform pattern) of distance information L obtained from the position detection sensor 22 described above. The second is a detection signal of the top dead center position during the reciprocating motion of the piston. The third is period equivalent information of piston reciprocating motion or information corresponding to one stroke.

  For example, in the case of a torque limiter pulley or clutch corresponding to the top dead center position of the compressor, the detection of the top dead center position and the period information during the reciprocating movement of the piston is reflected in the armature portion. The non-contact type detection sensor 26 is disposed so as to face the detection surface 25. As the detection sensor 26, for example, a photoelectric reflection type sensor is used.

  FIG. 3 is a flowchart showing an example of a processing procedure in capacity estimation according to the present embodiment. An example of the capacity estimation processing procedure will be described with reference to FIGS.

  In this embodiment, first, the piston 13 is at the top dead center based on the detection signal pattern of the distance information L from the position detection sensor 22 at the time of maximum capacity operation, the top dead center position information and the period information from the detection sensor 26. The distance information L detection signal pattern (displacement signal waveform pattern) of the position detection sensor 22 while moving from the position to the bottom dead center position (that is, one stroke of the piston) Record as a reference output waveform for comparison for estimation. Hereinafter, this detection signal pattern will be referred to as a displacement signal waveform pattern (A) for one stroke of the piston during the maximum displacement operation.

  Next, the piston 13 is top dead based on the detection signal pattern of the distance information L from the position detection sensor 22 and the top dead center position information and period information from the detection sensor 26 at the capacity operation (current operation) to be detected. The distance information L detection signal pattern (displacement signal waveform pattern) of the position detection sensor 22 during the movement from the point position to the bottom dead center position (that is, for one stroke of the piston) Record as output waveform for capacity estimation. This detection signal pattern is hereinafter referred to as an output waveform pattern (B) for capacity estimation during the current operation.

  Since the displacement to be detected is less than the maximum displacement, the waveform pattern (A) of the displacement signal for one stroke of the piston during the maximum displacement operation obtained above (the output waveform when the displacement is 100% in FIG. 2) is the current operation. An output waveform for displacement estimation (a waveform pattern (B) of a displacement signal for one stroke of the piston), that is, an output waveform when the displacement is 50% or 10% in FIG. 2 is included.

  Detection signal pattern of distance information L during maximum capacity operation (displacement signal waveform pattern (A) for one stroke of piston during maximum capacity operation) at an arbitrary increment from top dead center (for example, every 1%) Cutting out and comparing the degree of fitness with the detection signal pattern of distance information during the “capacity to be detected” operation (that is, the waveform pattern (B) of the displacement signal for one stroke of the piston during the current operation), for example, from 0% to the maximum Repeat to 100% of capacity. Among them, the capacity that most matches (adapts to) the detection signal pattern of the distance information of “capacity to be detected” is the estimated capacity during the “capacity to be detected” operation.

  In the evaluation of whether or not the detection signal pattern of the distance information L at the time of maximum capacity operation cut out with this arbitrary capacity matches the detection signal pattern of the distance information at the time of “capacity to be detected” operation, Thus, a cross-correlation coefficient can be used, a cumulative sum of residuals can be used, or a cumulative sum of deviations from an average value can be used.

For example, when the cross-correlation coefficient is used, the discharge capacity to be obtained is the capacity having the highest cross-correlation coefficient r calculated by the following formula 1, that is, the value closest to 1. Also, when using the cumulative sum of residuals or the cumulative sum of deviations from the average value, the following formula 2 (in the case of cumulative sum of residuals) and formula 3 (in the case of cumulative sum of deviations from the average value) The calculated cumulative sum I is the smallest, that is, the volume that is the value closest to 0 is the required discharge volume. In the following equations 1 to 3, a _i is the value of a certain point in the waveform pattern during the “capacity to be detected” operation, a with a bar is the average value of each point in the waveform pattern, and b _i is the maximum capacity operation. The value of a certain point in the current waveform pattern, b with a bar, indicates the average value of each point in the waveform pattern.

  Further, as described above, it is possible to cancel the unnecessary calculation halfway and reduce the calculation efficiency and calculation time. That is, when estimating the capacity during the current operation based on the cumulative sum of residuals or the cumulative sum of deviations described above, the capacity estimation means in the present invention exceeds the minimum value of the cumulative sum during the calculation of the cumulative sum. Sometimes the calculation can be stopped when the time is exceeded. For example, as shown in FIG. 4, when iterative computation is continued, if the minimum value of the current cumulative sum of residuals is exceeded, it is already possible to grasp the minimum value. This calculation is not necessary, and by canceling the calculation at that time, the number of processed data in the signal pattern to be calculated can be reduced, and the total time required for the calculation can be shortened.

  In addition, as described above, in the estimation of the capacity during the current operation, when it is considered that there is an appropriate estimated value between the discrete capacity estimation values, the capacity during the current operation can be more accurately determined by the interpolation method. It is possible to estimate. Also in the control flowchart shown in FIG. 3, such an interpolation step is set before the final step. For this interpolation, a general interpolation method may be adopted. For example, as shown in FIG. 5, the highest degree of fitness is obtained in a column of processed data relating to the estimated capacity (indicated by white circles in FIG. 5). When virtual data with a higher degree of fitness exists near the number of data points (near the local minimum in the example shown in the figure), the above data string is approximated with an approximate curve, and interpolation between predetermined data is performed. From the interpolation area, for example, by obtaining the minimum value of the interpolated approximate curve, the estimated capacity data with a higher degree of fitness is taken out, and the value is used as the estimated capacity at the time of the current operation. The capacity can be estimated.

  In the above embodiment, as shown in FIG. 2, when comparing the fitness, the detection signal pattern (displacement signal) of the distance information L for one stroke of the piston from the top dead center position to the bottom dead center position. As described above, for example, the discharge capacity may be estimated based on information of one cycle from the bottom dead center to the next bottom dead center with the top dead center position as the center. The waveform pattern of the displacement signal for one stroke of the piston may be acquired as the amount corresponding to half of the information of one cycle.

  Further, as described above, when the detection signal from the detected surface 21 of the piston (for example, the signal of the distribution shape of the reflection medium having high definition) changes significantly from the initial value due to scratches, wear, etc. during the compressor operation. However, by acquiring again the detection signal pattern obtained during the maximum capacity operation in that state, the influence of the change in the detection signal pattern of the reflection medium can be corrected, and the detection and capacity estimation accuracy during deterioration can be improved. The acquisition of the detection signal pattern obtained during the maximum capacity operation is not particularly required to stop or remove the compressor, and can be acquired during the operation, so that it can be acquired very easily.

  The capacity detection device according to the present invention can be applied to all piston type variable capacity compressors, thereby enabling easy and accurate capacity estimation at low cost, and through the capacity estimation, variable capacity compressors. Can be used for torque estimation.

DESCRIPTION OF SYMBOLS 1 Variable capacity type compressor 2 Capacity | capacitance detection apparatus 3 Pulley 4 Torque limiter mechanism 5 Drive shaft 6 Front housing 6a Inner peripheral surface 7 of front housing Cylinder block 8 Crank chamber 9 Rotor 10 Link mechanism 11 Swash plate 12 Cylinder bore 13 Piston 13a Piston 13a Neck 14 Shoe 15 Cylinder head 16 Suction chamber 17 Discharge chamber 21 Detected surface 22 of piston Position detection sensor 22a Detection head 23 of position detection sensor Controller 24 Air conditioner ECU
25 Detected part 26 Detection sensor

Claims (18)

A capacity detection device for a variable capacity compressor that performs gas compression by reciprocating movement of the piston and can change the capacity by changing the stroke of the piston,
(1) A position detection sensor disposed on the side of the piston, the shape of the piston being laterally moved in front of the position detection sensor by a reciprocating motion of the piston being a detection surface, A position detection sensor that outputs a displacement signal that approaches and moves away from the position detection sensor when a detection target point that is a part facing the position detection sensor is reciprocating a piston;
(2) The waveform pattern (A) of the displacement signal for one stroke of the piston during the maximum capacity operation is measured and stored, and the waveform pattern (B) of the displacement signal for the piston stroke of the current operation is detected. Estimating means for estimating a capacity during current operation corresponding to a piston stroke during current operation from a comparison between the waveform pattern (A) and the waveform pattern (B);
A capacity detection device for a variable capacity compressor, comprising:   The estimation means uses a signal of a period of one rotation of the compressor, a top dead center signal of the piston, or both signals as a reference in comparing the waveform pattern (A) and the waveform pattern (B). The capacity detection device for a variable capacity compressor according to claim 1, wherein the capacity during the current operation is estimated.   The estimating means compares a plurality of waveform patterns cut out from the waveform pattern (A) at a predetermined step rate with the waveform pattern (B), calculates a cross-correlation coefficient between them, and calculates the mutual correlation coefficient. The capacity detection device for a variable capacity compressor according to claim 1 or 2, wherein a capacity when the correlation coefficient shows a maximum value is an estimated capacity during the current operation.   The estimation means compares a plurality of waveform patterns cut out from the waveform pattern (A) at a predetermined step rate and the waveform pattern (B), and calculates a cumulative sum of residuals between the two, The capacity detection device for a variable capacity compressor according to claim 1 or 2, wherein a capacity when the cumulative sum of the residuals shows a minimum value is an estimated capacity at the time of current operation.   The estimation means calculates a cumulative sum of a difference between the deviation between the waveform pattern (A) and the average value and a deviation between the waveform pattern (B) and the average value, and a cumulative sum of the difference between the deviations. The capacity detection device for a variable capacity compressor according to claim 1 or 2, wherein a capacity when the value indicates a minimum value is an estimated capacity during current operation.   The estimation means stops the calculation when it exceeds the minimum value during the calculation of the cumulative sum, and updates the minimum value when it falls below the previous minimum value at the end of the calculation. The capacity detection device of the variable capacity compressor described in 1.   The estimation means interpolates a capacity area between the estimated capacity value indicating the maximum cross-correlation coefficient or the minimum cumulative sum and a calculated capacity value before and after the estimated capacity value, and the calculation is performed in the interpolation area. The variable capacity compression according to any one of claims 3 to 6, wherein when there is a value larger than the cross-correlation coefficient or smaller than the cumulative sum calculated so far, the value is set as an estimated capacity at the time of current operation. Capacity detector.   The capacity detection device for a variable displacement compressor according to any one of claims 2 to 7, wherein the signal of the period of one rotation of the compressor is obtained from a rotation signal of a drive source of the compressor.   The top dead center signal of the piston is obtained by a detection body provided at a portion corresponding to the top dead center of the piston of the driving pulley of the compressor and detection means provided at a position facing the detection body. The capacity detection device for a variable capacity compressor according to any one of claims 2 to 8.   The displacement detection device for a variable displacement compressor according to any one of claims 1 to 9, wherein a waveform pattern of the displacement signal for one stroke of the piston is obtained from a waveform pattern in a reciprocating motion of the piston.   The variable capacitance type according to any one of claims 1 to 10, wherein the position detection sensor detects at least one of an uneven shape distribution, an electromagnetic characteristic distribution, and a light reflection characteristic distribution on a detection surface of the piston. Compressor capacity detection device.   The capacity detection device for a variable capacity compressor according to claim 11, wherein the position detection sensor includes an eddy current sensor, an electromagnetic induction sensor, a capacitance sensor, or a photoelectric reflection sensor.   The capacity detection device for a variable capacity compressor according to claim 12, wherein a paint having magnetic properties is applied to a detection surface of the piston, or a magnet is embedded.   The capacity detecting device for a variable capacity compressor according to claim 12, wherein a paint having optical characteristics is applied to a surface to be detected of the piston, or a light reflector is embedded.   The estimation means re-records the waveform pattern (A) in that state even when the detection signal from the position detection sensor changes from the initial value due to scratches, wear, etc. on the detected surface of the piston. The capacity detection device for a variable capacity compressor according to claim 1, wherein the capacity during current operation is estimated by correcting the influence due to the change.   A variable capacity compressor provided with the capacity detection device according to claim 1.   The variable capacity compressor according to claim 16, wherein the torque of the compressor is estimated from the estimated capacity and at least the discharge pressure and suction pressure of the compressor.   The variable capacity compressor according to claim 16 or 17, wherein the opening degree of a capacity control valve that varies the capacity of the compressor is controlled by using the estimated capacity as input information.

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