JP2002161863A - Piston collision prevention control method for linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple piston collision prevention control method for a linear compressor capable of reducing a stroke of a piston and preventing the piston from colliding against a cylinder head surely, stably, highly efficiently and with high reliability at low cost without fluctuating top clearance of the piston. SOLUTION: This piston collision prevention control method for the linear compressor comprises a process for driving the linear compressor by drive frequency at which drive frequency of the piston agrees with resonance frequency determined by gas spring constant, a process for reading a current position of the piston and an upper limit position set value of travel of the piston to compare the current position of the piston with the upper limit position set value of the piston, and a process for supplying a drive frequency command value lower than the resonance frequency to the piston to reduce an amplitude of the piston when the current position of the piston exceeds the upper limit position set value of the piston.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling collision prevention of a piston of a linear compressor which compresses refrigerant by reciprocating a piston in a cylinder by a linear motor.

[0002]

2. Description of the Related Art In recent years, a linear compressor has been developed as a mechanism for compressing a refrigerant gas in a refrigeration system.
For example, there is one disclosed in JP-A-11-324911. A conventional example will be described with reference to FIG. As shown, a position command value generator (130), a position / speed controller (131), a current command value generator (132), a position / speed detector (133),
Top and bottom dead center detector (134), current / speed phase difference detector (1
35), a current gain control section (136), an amplitude neutral position control section (137), and a frequency control section (138). The position / speed detection unit (133) takes in the position data Pa from the sensor signal processing circuit, and
ow, and the current position value Pnow is differentiated to obtain the current speed value Vnow. Top and bottom dead center detector (134)
Is the top dead center side amplitude between the top dead center and the origin of the piston, and the bottom dead center between the bottom dead center and the origin based on a series of current position values Pnow obtained from the position / speed detection unit (133). Detect the point side amplitude. The detection of the top dead center side amplitude and the bottom dead center side amplitude is performed each time one cycle of the position command Pref ends, that is, each time the position command Pref passes through the zero cross point. The current / velocity phase difference detection unit (135) includes the current position value Vnow generated by the position / velocity detection unit (133) and the current command value Ire generated by the current command value generation unit (132).
The phase difference from f is detected. The phase difference is detected every time one cycle of the current position value Pnow ends, that is, the current position value P
This is performed every time the now passes through the zero cross point. The position command value generation unit (130) includes a sine table stored in a memory, an amplitude A, an angular frequency ω, a shift amount B,
A position command value Pref is generated based on the equation Pref = Asinωt + B (sine function), and the generated position command value P
ref is given to the position / speed controller (131). The position / speed control unit (131) includes a position command value Pref generated by the position command value generation unit (130) and a position / speed detection unit (133).
And the deviation Pref-Pn
ow, and generates a speed control value Vc based on a difference Vref-Vnow between the speed command value Vref and the current speed value Vnow generated by the position / speed detection unit (133). . Current command value generator
(132) is a speed control value Vc generated by the position / speed control unit (131), a current gain Gi, and an expression Iref = Gi.
A current command value Iref is generated based on Vc and the current command value Iref is further converted into a control signal φc and given to the motor driver. The control of the output current I of the motor driver is performed by, for example, a PWM method. Current gain control section
(136) compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit (134), and determines the larger one of the top dead center side amplitude and the bottom dead center side amplitude. Is the maximum amplitude current value Anow, and the value of the current gain Gi used in the current command value generation section (132) is set so that the current value of the maximum amplitude Anow matches a predetermined maximum amplitude target value Aref. Control is performed every cycle. Also,
The current gain control unit (136) determines whether the phase difference detected by the current / speed phase difference detection unit (135) exceeds a predetermined allowable value once every several hundred cycles of the vibration of the piston. If it exceeds, the current command value generator (1
The value of the current gain Gi used in 32) is reduced by several percent. In this way, the position / speed by the position / speed control unit (131)
By controlling the maximum amplitude in addition to the speed control and reducing the current gain Gi by several percent prior to the frequency control, it is possible to avoid collision between the piston head and the upper wall of the cylinder. Further, in order to avoid the collision of the piston when the load (gas pressure) suddenly decreases, the size of the piston is limited between the target position of the top dead center of the piston and the limit position where the piston collides with the cylinder upper wall. Set two excess criteria and As for the large excess criterion, when the current position of the piston exceeds the excess criterion, the gain Gi of the current gain control unit (136) is reduced by several tens of percent. When the average value of the piston at the top dead center position for two to several cycles exceeds the excess judgment criterion, the current gain control unit (1)
36) Decrease the gain Gi by several percent. by this,
The collision between the piston and the upper wall of the cylinder when the load (gas pressure) suddenly drops can be reliably avoided. The amplitude neutral position control unit (137) compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit (134), and calculates the difference between the top dead center side amplitude and the bottom dead center side amplitude. Is controlled each time one cycle of the position command value Pref is completed, so that the shift amount B used in the position command value generation unit (130) is reduced.
That is, when the top dead center side amplitude is larger than the bottom dead center side amplitude, the amplitude neutral position control unit (137) corrects the shift amount B to the negative side (downward), and adjusts the top dead center side amplitude. Is smaller than the bottom dead center side amplitude, the shift amount B is corrected to the positive side (upward). FIG. 22 determines in step S151 whether the current position value is greater than the excess criterion on the top dead center side,
If NO, it is further determined in step S152 whether or not the current position value is smaller than an excess determination criterion on the bottom dead center side. If the answer is YES in step S151 or the answer is YES in step S152, there is a great risk of a piston collision, so the process proceeds to step S153, and the current gain is significantly reduced (for example, several tens%). I do. If it is determined NO in step S152, the process proceeds to step S152.
The flow shifts to 154, where it is determined whether the position command value has zero-crossed from the positive side to the negative side.
The process proceeds to 155, where the third counter is incremented. Subsequently, in step S156, it is determined whether or not the value of the third counter has reached a set value (for example, 2 to 5).
If yes, in step S157, the average value of the piston maximum position value (for collision avoidance processing) and the average value of the minimum position value (for collision avoidance processing) since the third counter was reset are calculated. Then, in step S158, it is determined whether or not the average value of the position maximum value (for collision avoidance processing) is greater than the upper dead center side excess determination criterion. If NO, the position minimum value is further determined in step S159. It is determined whether or not the average value (for collision avoidance processing) is smaller than the excess determination criterion on the bottom dead center side. In step S158, the determination is yes,
Alternatively, when the determination is YES in step S159, there is a possibility that the piston will collide.
To reduce the current gain by several percent. Next, in step S161, after the held position maximum value (for collision avoidance processing) and position minimum value (for collision avoidance processing) are reset,
In step S162, the third counter is reset, and the flow shifts to step S163. Step S154
When it is determined to be NO in step S156
Also, when it is determined to be NO, the process proceeds to step S163, where the position maximum value (for collision avoidance process) and the position minimum value (for collision avoidance process) for the cycle are detected, held, and the process returns. According to the above-described collision avoidance routine, when the position of the piston exceeds the criterion in a certain cycle, the current gain is increased by several tens% at that time.
It is reduced and the collision of the piston is reliably avoided. or,
Regarding the excess criterion, when the average value of the top dead center position or the bottom dead center position of the piston in two to several cycles exceeds the criterion, in the next cycle, the current gain is reduced by several percent, Collisions are avoided.

[0003]

In a conventional control method, when a collision prevention control is performed by a linear compressor having a configuration in which a pair of compression chambers are horizontally opposed to each other, basically, a position obtained from a piston position detection is used. Create a current command according to the data,
When the piston may collide with the cylinder while always performing the top clearance control, the current command is reduced to avoid the collision. In the case of a compressor with two compression chambers, all components such as spring, suction and discharge valves are 2
Set required. The number of parts increases, the cost increases, the structure becomes complicated, and reliability remains an issue. In the conventional collision prevention control, when controlling a linear compressor having one compression chamber, only the piston surface on the discharge side receives the discharge pressure, so that the ratio affected by the discharge pressure is very high. Sensitive to changes such as sudden changes, for example, there is a risk of collision near the top dead center of the piston. When the motor current is reduced by the set value, the amplitude of the piston first decreases and the piston once moves away from the cylinder head. When the discharge pressure decreases, the piston approaches the cylinder head again and collides depending on the load condition. Since the resonance frequency is determined by the combined value of the mechanical spring and the gas spring, when the current value is reduced, the resonance frequency of the gas spring changes and the combined resonance frequency also changes, so that the motor current decreases. In the transient state of the cycle, the resonance frequency changes, and when the drive frequency and the resonance frequency become close to each other, the resonance magnification increases, the amplitude of the piston increases, and the behavior of the piston becomes unstable, leading to a decrease in efficiency and reliability. Also, if the load increases rapidly, the center of the piston is offset to the non-compression side, so that if the amplitude of the spring exceeds the limit, the spring will be damaged. The same result is obtained when the power supply voltage suddenly changes. When there is a risk of collision of the piston, the collision of the piston cannot be reliably avoided under any load condition only by reducing the current of the linear motor.

Accordingly, the present invention has been made to solve the conventional problems, and its object is to reduce the stroke of the piston and to achieve high efficiency, stability, and high reliability without changing the top clearance of the piston. Accordingly, the present invention proposes a simple and low-cost piston collision prevention control method for a linear compressor that can reliably prevent a piston from colliding with a cylinder head.

[0005]

According to a first aspect of the present invention, there is provided a linear compressor having a piston compression preventing control method, wherein a driving frequency of a piston is made to coincide with a resonance frequency determined by a spring and a gas spring constant. Driving the linear compressor, and reading the current position of the piston and an upper limit position setting value of the movement of the piston, and comparing the current position of the piston with the upper limit position setting value of the piston, Supplying a drive frequency command value higher or lower than the resonance frequency to the piston when the current position of the piston exceeds the upper limit position set value of the piston to reduce the amplitude of the piston. According to a second aspect of the present invention, there is provided the linear compressor piston collision prevention control method according to the first aspect, wherein the upper limit position set value is set according to a difference between a top dead center and a top dead center reference value. It is characterized by having a plurality of set values. According to a third aspect of the present invention, in the method for controlling prevention of collision of a piston of a linear compressor according to the second aspect, at least two or more upper limit positions are set when the current position of the piston exceeds the upper limit position set value of the piston. Among the values, as the upper limit position set value of a larger value is exceeded, a frequency command value higher or lower than the resonance frequency is supplied. According to a fourth aspect of the present invention, there is provided the piston collision prevention control method for a linear compressor according to the first aspect, wherein the condenser, the decompression expander, and the evaporator constitute a refrigeration cycle together with the piston collision prevention control. After the step of supplying a drive frequency command value higher or lower than a resonance frequency to the piston to reduce the amplitude of the piston, the opening degree of the pressure reducing expander is controlled to set the center of amplitude of the piston. The method further comprises a step of offsetting in the negative direction to bring the amplitude center of the piston closer to the anti-compression side. According to a fifth aspect of the present invention, in the control method for preventing collision of a piston of a linear compressor according to the fourth aspect, when the current position of the piston exceeds the upper limit position set value of the piston, at least two or more upper limit position set values are set. The method further includes a step of supplying a frequency command value higher or lower than the resonance frequency and narrowing the opening of the pressure reducing expander as the value exceeds the upper limit position set value of the larger value. The piston collision prevention control method for a linear compressor according to the present invention according to claim 6,
Supplying a direct current to the piston to drive the linear compressor, reading the current position of the piston and the upper and / or lower limit position set values of the piston, setting the current position of the piston and the upper or lower limit position of the piston And comparing the value with the value, when the current position of the piston exceeds the upper limit or lower limit position set value of the piston, by controlling the DC current component to offset the center of amplitude of the piston in the negative or positive direction. Bringing the piston closer to the compression side or the anti-compression side. Claim 7
According to a first aspect of the present invention, in the method for preventing collision of a piston of a linear compressor according to the first aspect, when a current position of the piston exceeds a set value of an upper limit position of the piston, the DC current component is controlled to be negative. It is characterized in that the amplitude center of the piston is offset in the negative direction. According to an eighth aspect of the present invention, in the method for controlling prevention of collision of a piston of a linear compressor according to the first aspect, when the current position of the piston exceeds a lower limit position set value of the piston, the DC current component is positively controlled. The amplitude center of the piston is offset in the positive direction. According to a ninth aspect of the present invention, there is provided the linear compressor piston collision prevention control method according to the sixth aspect, further comprising a plurality of upper limit and / or lower limit position setting values of the piston, and the current position of the piston is When exceeding the upper limit or lower limit position set value, the DC component of the linear motor input current is increased or decreased as the value exceeds the larger upper limit or lower limit position set value of at least two or more upper limit or lower limit set values. The method further comprises the step of: A piston collision prevention control method for a linear compressor according to the present invention according to claim 10 is a piston collision prevention control method for a linear compressor that forms a refrigeration cycle together with a condenser, a decompression expander, and an evaporator. Controlling the linear compressor and reading the current piston position and the upper and / or lower limit position set values of the piston, and comparing the current position of the piston with the upper or lower limit position set value of the piston When the current position of the piston exceeds the upper limit or lower limit position set value of the piston, by controlling the opening and closing degree of the pressure reducing expander to offset the amplitude center of the piston in the negative or positive direction. Bringing the amplitude center of the piston closer to the compression side or the anti-compression side. The control method for preventing collision of a piston of a linear compressor according to the present invention according to claim 11 includes a condenser, a decompression expander,
And a piston collision prevention control method of a linear compressor that constitutes a refrigeration cycle together with the evaporator, the step of driving the linear compressor, the current position of the piston and a plurality of upper or lower limit position set values of the piston, Reading the current number of revolutions and rotation setpoints of the condenser blower or the evaporator blower, the current position of the piston is located between at least two upper or lower limit setpoints, and the current number of revolutions of the blower; Is higher than the rotation setting,
Reducing the current value of the motor. A method for controlling collision prevention of a piston of a linear compressor according to the present invention according to claim 12 includes the steps of: controlling a power supply voltage to drive the linear compressor; the current position of the piston; And when the current position of the piston is between at least two upper limit set values and the current voltage is higher than the voltage set value, the voltage is reduced to reduce the motor current value. And a step. Claim 13
The method for controlling the collision prevention of a piston of a linear compressor according to the present invention includes the steps of controlling a power supply voltage to drive the linear compressor, the current position of the piston and a plurality of upper limit position set values of the piston and the current voltage and Read the voltage setting,
Offsetting the voltage to a negative side when the current position of the piston is between at least two upper limit position set values and the current voltage is higher than the voltage set value. The present invention described in claim 14 is based on claim 1.
The method for controlling collision prevention of a piston of a linear compressor according to the above, further comprising: calculating a differential speed from position information of the piston to calculate a set speed for performing the collision prevention control based on a current speed. It is characterized by.

[0006]

According to the first embodiment of the present invention, when the present position of the piston exceeds the set value of the upper limit position of the piston, the piston is controlled by the resonance frequency. By supplying a high or low drive frequency command value to reduce the piston amplitude,
Even if the stroke is further extended, it is possible to prevent the piston from colliding with the cylinder head.

According to the piston compressor collision prevention control method for a linear compressor according to the second embodiment of the present invention, the upper limit position set value is set to a plurality of values in accordance with the difference between the top dead center and the top dead center reference value. With the set value of, it is possible to perform the collision prevention control according to the state of the sudden load change.

According to the piston compressor collision prevention control method for a linear compressor according to the third embodiment of the present invention, the present position of the piston is set to a larger one of at least two or more upper limit position set values. By supplying a frequency command value higher or lower than the resonance frequency as the value exceeds the set value, it is possible to perform the collision prevention control according to the sudden load change state.

According to a fourth embodiment of the present invention, there is provided a method for controlling a piston to prevent collision of a linear compressor, wherein a drive frequency command value higher or lower than a resonance frequency is supplied to the piston to reduce the amplitude of the piston. After that, the opening degree of the pressure reducing expander is controlled to offset the center of amplitude of the piston in the negative direction to bring the center of amplitude of the piston closer to the anti-compression side, thereby preventing the piston from colliding with the cylinder again.

According to the piston compressor collision prevention control method for a linear compressor according to a fifth embodiment of the present invention, the present position of the piston is set to a larger one of at least two or more upper limit position set values. As the frequency exceeds, the frequency command value higher or lower than the resonance frequency is supplied, and the opening angle is further narrowed, so that the sudden change of the load can be achieved, and the collision prevention control can be performed more reliably.

According to the piston compression prevention control method for a linear compressor according to the sixth embodiment of the present invention, when the current position of the piston exceeds the upper limit or lower limit position set value of the piston, the DC current component is controlled. By offsetting the center of amplitude of the piston in the negative direction or the positive direction and moving the piston closer to the compression side or the anti-compression side, collision prevention control can be performed efficiently and reliably.

According to the piston collision prevention control method of the linear compressor according to the seventh embodiment of the present invention, when the current position of the piston exceeds the set upper limit position of the piston, the DC current component is controlled to be negative. By offsetting the center of amplitude of the piston in the negative direction by adjusting the center of amplitude of the piston earlier, the collision prevention control can be more reliably performed.

According to the piston collision prevention control method of the linear compressor according to the eighth embodiment of the present invention, when the current position of the piston exceeds the lower limit position set value of the piston, the DC current component is positively controlled. By offsetting the center of amplitude of the piston in the positive direction, the anti-collision control can be performed more reliably by adjusting the center of amplitude of the piston faster.

According to the ninth embodiment of the present invention, the current position of the piston is at least two or more of the upper limit and the lower limit position set values. As the value exceeds the lower limit position set value, the DC component of the linear motor input current is increased or decreased, whereby the collision prevention control can be more instantaneously and more reliably performed in accordance with a sudden load change state.

According to the control method for preventing the collision of the piston of the linear compressor according to the tenth embodiment of the present invention, when the current position of the piston exceeds the set value of the upper or lower limit position of the piston, the opening / closing degree of the pressure reducing expander is reduced. By controlling and offsetting the center of amplitude of the piston in the negative or positive direction and bringing the center of amplitude of the piston closer to the compression side or the opposite side of compression, the collision pressure can be more reliably controlled by increasing the discharge pressure. it can.

According to the control method for preventing collision of a piston of a linear compressor according to the eleventh embodiment of the present invention, the present position of the piston is located between at least two upper limit or lower limit position set values, and When the rotation speed for heat exchange in the cycle is higher than the rotation set value, the motor current value is reduced to prevent the spring from oscillating in the anti-compression side beyond the spring amplitude design value, improving the reliability of the spring. Can be achieved.

According to the control method for preventing collision of a piston of a linear compressor according to the twelfth embodiment of the present invention, the current position of the piston is located between at least two upper limit position set values, and the current voltage is equal to the voltage. By lowering the voltage when the voltage is higher than the set value to reduce the motor current value, it is possible to reliably prevent a collision even when a sudden change in the power supply voltage occurs.

According to the thirteenth embodiment of the present invention, the current position of the piston is between at least two upper limit position set values, and the current voltage is the voltage. By offsetting the voltage to the negative side when the voltage is higher than the set value, even when a sudden change of the power supply voltage occurs, it is possible to instantaneously and reliably prevent the amplitude center of the piston from colliding with the offset.

According to the piston collision prevention control method for a linear compressor according to the fourteenth embodiment of the present invention, the differential velocity is calculated from the piston position information to perform the collision prevention control based on the current velocity. By calculating the set speed,
The collision of the piston can be reliably prevented by reducing the amplitude of the piston earlier.

[0020]

FIG. 1 shows the construction of a linear compressor. The linear compressor includes an airtight container 80, a cylinder unit 10 housed in the airtight container 80, and a support mechanism 90 and a cylinder unit 10 inside the airtight container 80.
A linear motor portion 100 having a movable portion 40 and a fixed portion 50 to generate axial thrust in the piston portion 20 by magnetic force; And a suction / discharge mechanism unit 60 for performing suction / discharge of the liquid. The piston section 20 is elastically supported by the spring mechanism section 70. The closed container 80 is formed of a cylindrical container, and forms a space 84 inside. All the components of the linear compressor are stored in the space 84. Further, the closed container 80 is provided with a suction pipe 85 for introducing a refrigerant from outside the closed container 80 and a discharge pipe 67 for discharging the refrigerant outside the closed container 80. The support mechanism 90 includes
Coil springs 91 are disposed at one end and the other end in the sealed container 80, and elastically support the cylinder portion 10 in the sealed container 80 to reduce vibration transmission from the cylinder portion 10 to the sealed container 80. To work. The coil spring 91 provided at one end is interposed between the cylinder head cover 46 and the front wall plate 82 of the sealed container 80, and the coil spring 91 provided at the other end is provided with Fixed part 50 of linear motor part 100 fixed to
It is interposed between the support plate 92 connected to the side and the rear wall plate 83 of the sealed container 80. The linear motor section 100 includes the movable section 40 and the fixed section 50 as described above. The movable part 40 includes a cylindrical holding member 41 and a permanent magnet 4 fixed to the outer peripheral side thereof.
Consists of two. The other end of the cylindrical holding member 41 is fixed to the flange 24. Therefore, the cylindrical holding member 41
And the piston part 20 are connected. On the other hand, the fixing portion 50 includes an inner yoke 51, an outer yoke 52, and a coil 53.
Consists of The inner yoke 51 is formed of a cylindrical body, is fitted on the outer periphery of the cylindrical body 13 of the cylinder 10, and is circumscribed and fixed to the boss 12. A minute gap is formed between the outer peripheral surface of the inner yoke 51 and the inner peripheral surface of the cylindrical holding member 41 of the movable section 40. The outer yoke 52 is also formed of a cylindrical body, and its circumferential surface is fixed to the flange portion 11 of the cylinder portion 10 while maintaining a small gap with the outer circumferential surface of the permanent magnet 42 of the movable portion 40. The coil 53
Is fixed to the outer yoke 52 and is disposed at a position facing the permanent magnet 42. A support 54 for fixing the support plate 92 is fixed to the other end of the outer yoke 52. The inner yoke 51, the outer yoke 52, and the movable part 4
0 is concentrically held with high precision. Spring mechanism 70
Is composed of a plurality of (two in the illustrated) flat plate-like spring plates 71 disposed on the other end side of the piston portion 10.
Is provided between the bolt 25 screwed to the piston part 20 and the support member 54 fixed to the cylinder part 10. The spring plate 71 is formed by stacking a plurality of spring plate members 71a. When the coil 53 of the fixed part 50 is energized, a magnetic force or thrust proportional to the current is generated between the coil 53 and the permanent magnet 41 of the movable part 40 according to Fleming's left-hand rule. A driving force that moves in the axial direction acts on the movable section 40 by the thrust. Since the cylindrical holding member 41 of the movable section 40 is connected to the spring mechanism section 60, the piston section 20 moves. Here, energization of the coil 53 is given by an AC wave, and forward and reverse thrusts are alternately generated in the linear motor portion. The piston portion 20 reciprocates due to the alternately generated forward and reverse thrusts. The refrigerant gas is introduced from the suction pipe 85 into the closed container 80. The introduced refrigerant gas is sucked into the low-pressure chamber 46a from the suction pipe 85 in the closed vessel 80, passes through the suction valve 44, and
Enter 8. Then, the refrigerant gas is compressed by the piston portion 20, passes through the discharge valve 48 attached to the discharge port 45b of the cylinder head 45, passes through the high-pressure chamber 46b, and is discharged from the discharge pipe 67. Also, the piston section 20
The vibration of the cylinder portion 10 caused by the reciprocating motion of is controlled by a plurality of coil springs 91.

FIG. 2 is a diagram showing a configuration of a refrigeration cycle according to an embodiment of the present invention. Linear compressor 112, indoor heat exchanger 113, decompressor 119, outdoor heat exchanger 116
Are connected in a ring. The AC voltage from the AC power supply 130 is converted into DC by the rectifier 102 and supplied to the inverter 104. The inverter 104 applies an AC magnetic field to the winding of the linear motor of the linear compressor 112 to generate a thrust.
DC voltage detection section 103 detects a DC voltage. The current detector 107 detects the current flowing to the linear compressor 112 with the current detector 106. The piston position detector 109 detects the positional relationship between the piston and the cylinder based on the signal from the stroke detector 108. The FAN control unit 121
The internal FAN control unit 115 and the external FAN control unit 118
The rotation speeds of N114 and N117 are respectively detected. The decompressor / expander controller 120 controls the opening / closing degree of the decompressor / expander 119. The inverter control unit 105 can perform a rapid load change or a voltage change based on information from each of the control units.
Prevent collision between piston and cylinder head and ensure spring reliability.

Hereinafter, a first embodiment of a piston collision prevention control method for a linear compressor according to the present invention will be described with reference to FIG. In the figure, a drive frequency command value having a sine wave having a resonance frequency determined by a spring and a gas spring constant;
sinFsinc is given to the linear compressor 112 (step S1). Here, the resonance frequency f of the piston motion is determined by the relationship between the mass m of the movable mass of the piston section 20 and the like and the spring system constant k. Note that the spring system constant k is
1 and the gas spring constant kg generated by the compressed gas in the compression chamber 68. That is, the resonance frequency f is represented by the following relational expression. f = 1 / 2π√ (k / m) k = km + kg− (1) Next, a preset upper limit position set value Ptag at the top dead center of the piston is read from the data table.
In addition, the position information of the piston (amplitude center, top clearance, piston offset amount, etc.) is read into the inverter control unit 105 from the piston position detection unit 109 for each cycle (step S2). Next, the upper limit position set value Ptag of the piston is compared with the current position Pnow of the piston. When the current position Pnow of the piston exceeds the upper limit position set value Ptag of the piston (step S39), the drive frequency is changed from the resonance frequency. The resonance magnification is reduced by shifting to a higher or lower frequency side, and control is performed so as to reduce the amplitude width of the piston (step S4).

FIG. 4 shows the relationship between the drive frequency and the amplitude value of the piston. As shown in the figure, when the drive frequency is controlled to match the resonance frequency determined by the spring and the gas spring constant, the resonance magnification is increased and the amplitude value of the piston becomes maximum. The amplitude value of the piston decreases as the drive frequency shifts from the resonance frequency to a higher or lower frequency side. When the piston exceeds the upper limit position set value and switches to the protection control mode, the upper limit position set value Ptag flag is set and the target current is reset (step S5). on the other hand,
If the upper limit position set value Ptag of the piston is not exceeded, the upper limit position set value Ptag flag is reset (step S).
6). Thus, when the resonance frequency is determined by the load condition, the current flowing through the linear compressor is controlled, and the amplitude of the piston is adjusted. As a result, the displacement is varied. When the load suddenly drops from the stable state, the pressure applied to the piston drops sharply, and the center of amplitude of the piston is offset to the compression side.However, by utilizing the resonance characteristics, the piston does not collide with the cylinder head. Works.

FIG. 5 shows a second embodiment of the piston collision prevention control method. After the above step S1, in step S7, the current position Pnow of the piston and the two upper limit position set values Ps, P
Read b. In step S3, the current piston position Pno
w is compared with the first upper limit position set value Ps. When the current piston position Pnow exceeds the first upper limit position set value Ps, the drive frequency is changed from the resonance frequency by Δ in step S4.
Decrease by F1. When the piston switches to the protection control mode beyond the upper limit position set value, the upper limit position set value Ps flag is set and the target current is reset (step S).
8). On the other hand, if the upper limit position set value Ps of the piston is not exceeded, the upper limit position set value Ps flag is reset (step S9). Further, the current position Pnow is compared with the upper limit position set value Pb closer to the cylinder head, and when the current position Pnow of the piston exceeds the upper limit position set value Pb (step S10), the drive frequency is further reduced from the resonance frequency. By greatly shifting by ΔF2, the amplitude of the piston is greatly reduced to prevent collision (step S11). In this way, by setting a plurality of upper limit position setting values, it is possible to perform collision prevention control in accordance with a sudden load change state. When the piston exceeds the upper limit position set value and switches to the protection control mode, the upper limit position set value P
The b flag is set and the target current is reset (step S12). On the other hand, if the value does not exceed the upper limit position set value Pb of the piston, the upper limit position set value Pb flag is reset (step S13).

FIG. 6 shows a third embodiment of the piston collision prevention control method. After the above step S1, in step S2, the current piston position Pnow and the upper limit position set value Ptag are read. The upper limit position set value Ptag of the piston is compared with the current position Pnow of the piston. When the current position Pnow of the piston exceeds the first upper limit position set value Ps (step S3), the resonance frequency is changed in step S4. The amplitude width of the piston is reduced to reduce the discharge pressure. But,
When the resonance frequency approaches the changed drive frequency due to a change in the gas spring constant, there is a risk that the piston will collide again with the cylinder. For this purpose, the opening degree of the pressure reducing expander is closed. Thus, the discharge pressure is increased, the center of amplitude of the piston shifts to the anti-compression side, and collision of the piston is prevented (step S14).

FIG. 7 shows the relationship between the opening / closing degree of the pressure reducing expander and the offset amount of the piston amplitude center under a certain load condition. In the figure, when the discharge pressure is increased by narrowing the opening of the pressure reducing expander, the piston has a free piston configuration without a crank mechanism. Offset.

FIG. 8 shows a fourth embodiment of the piston collision prevention control method. After the above step S1, in step S7, the current piston position Pnow and the two upper limit position set values P of the piston are set.
Read s and Pb. The two upper limit position setting values are set according to the magnitude of the difference between the top dead center and the top dead center reference value. Then, the upper limit position set value Ptag of the piston is compared with the current position Pnow of the piston. When the current position exceeds the upper limit position set value (step S3), the drive frequency is shifted from the resonance frequency by ΔF1 in step S4, In step S8, an upper limit position set value Ps flag is set. If not, the upper limit position set value Ps flag is reset (step S9). Further, as described above, in step S14, the opening angle of the pressure reducing expander is reduced by ΔE1. In step S10, the current position and the upper limit position set value Pb closer to the cylinder head are compared, and when the current position Pnow of the piston exceeds the upper limit position set value Pb, the drive frequency is changed from the resonance frequency in step S11. Further, the amplitude of the piston is greatly reduced by ΔF2. Then, an upper limit position set value Pb flag is set in step S12. On the other hand, if the value does not exceed the upper limit position set value Pb of the piston, the upper limit position set value Pb flag is reset (step S13). Step S1
At 5, the opening angle of the decompression expander is further reduced to ΔE2,
Offset the center of amplitude of the cylinder to the anti-compression side.
By setting a plurality of upper limit position setting values and adjusting the resonance frequency and the opening degree of the pressure reducing expander, the collision prevention control can be more reliably performed in accordance with a sudden load change state.

FIG. 9 shows a fifth embodiment of the piston collision prevention control method. After the above step S1, in step S2, the current piston position Pnow and the upper limit position set value Ptag are read. In step S3, the upper limit position set value Ptag of the piston
Is compared with the current position Pnow of the piston. When the current position Pnow of the piston exceeds the upper limit position set value Ptag, the DC component flowing through the linear motor is offset negatively (step 16). That is, when the current I = I0 sinωt
I is added to make I = I0 sin ωt + △ I. Therefore, a DC component is added to the thrust of the linear motor, that is, the exciting force, and the center of amplitude of the piston is instantaneously controlled to be offset.

Here, FIG. 10 shows the relationship of the center of amplitude of the piston to the addition of the direct current. In the figure, when the current of the DC component is increased, the amplitude center of the piston is offset in the + direction. Therefore, the center of amplitude of the piston moves in the direction of approaching the compression side, that is, the cylinder head. On the other hand, when the DC component current is reduced, the center of amplitude of the piston is offset in the negative direction. Therefore, the center of amplitude of the piston moves in a direction approaching the anti-compression side. The upper limit position set value Ptag flag is set and the target current is reset (step S5). On the other hand, if the value does not exceed the upper limit position set value Ptag of the piston, the upper limit position set value Ptag
The g flag is reset (step S6).

FIG. 11 shows a sixth embodiment of the piston collision prevention control method. After the above step S1, in step S7, the current piston position Pnow and the two upper limit position set values Ps and Pb of the piston are read. Then, in step 3, the current position Pnow of the piston is compared with the initial upper limit position set value Ps. When the current position exceeds the upper limit position set value, only the DC component -ΔIs is applied to the linear motor in step S16. ,
The center of amplitude of the piston is moved to the anti-compression side. When the piston exceeds the upper limit position set value and switches to the protection control mode, the upper limit position set value Ps flag is set and the target current is reset (step S8). On the other hand, if the upper limit position set value Ps of the piston is not exceeded, the upper limit position set value Ps flag is reset (step S9). In step S10, the current position is compared with the upper limit position set value Pb closer to the cylinder head. When the current position Pnow of the piston exceeds the upper limit position set value Pb, the direct current is further increased to the linear motor in step S17. Component is applied by -ΔIb,
The center of amplitude of the piston is instantaneously moved greatly toward the anti-compression side. By setting a plurality of upper limit position set values and adjusting the DC component to the linear motor, the collision prevention control can be instantaneously and more reliably performed according to the state at the time of a sudden change in load. When the piston exceeds the upper limit position set value and is switched to the protection control mode, the upper limit position set value Pb flag is set and the target current is reset (step S12). On the other hand, if the value does not exceed the upper limit position set value Pb of the piston, the upper limit position set value Pb flag is reset (step S13).

FIG. 12 shows a seventh embodiment of the piston collision prevention control method. After step S1, in step S18, the current position Pnow and the lower limit position set values Pds and Pdb at the two bottom dead centers of the piston are read. The two lower limit position setting values are set according to the magnitude of the difference between the bottom dead center and the bottom dead center reference value. In step 19, the current position Pnow is compared with the first lower limit position set value ds of the piston to determine the current position Pnow.
When w exceeds the initial lower limit position set value ds of the piston,
The piston is moved to the compression side by a DC component + ΔIs on the linear motor (step 20). Then, the lower limit position set value Pds flag is set and the target current is reset (step S21). On the other hand, the lower limit position set value Pd of the piston
If it does not exceed s, the lower limit position set value Pds flag is reset (step S22). Further, in step S23, the current piston position Pnow is compared with the lower limit position set value Pdb closer to the anti-compression side. When the piston current position exceeds the lower limit position set value Pdb, the DC component is further increased by + ΔIb in step S24. Add and move the piston to the compression side. Then, the lower limit position set value Pdb flag is set and the target current is reset (step S25). on the other hand,
If the lower limit position setting value Pdb of the piston is not exceeded, the lower limit position setting Pdb flag is reset (step S2).
6).

FIG. 13 shows an eighth embodiment of the piston collision prevention control method. After the above step S1, in step S27, the current position Pnow, the upper limit position set value Ps of the piston, and the lower limit position set value Pdb are read. In step S3, the current position is compared with the upper limit position set value Ps. When the current position of the piston exceeds the upper limit position set value, the DC component is reduced by -Δ in step S16.
Is is added, and the piston is moved to the anti-compression side. When the piston moves to the protection control mode beyond the upper limit position, the upper limit position set value Ps flag is set and the target current is reset (step S8). On the other hand, if the upper limit position set value Ps of the piston is not exceeded, the upper limit position Ps flag is reset (step S9). In step S27, the current piston position Pnow and the lower limit position set value Pdb are further determined.
When the lower limit position setting value exceeds the current position, the DC component is offset toward the compression side by + ΔIb in step S28. Thus, even if the load changes suddenly, the piston does not exceed the upper limit position set value and the lower limit position set value,
Along with preventing the collision of the piston, the reliability of the spring is improved without the spring oscillating to the anti-compression side more than the designed value. Then, the lower limit position set value Pdb flag is set and the target current is reset (step S25). On the other hand, when the lower limit position set value Pdb of the piston is not exceeded, the lower limit position Pdb
The flag is reset (step S26).

FIG. 14 shows a ninth embodiment of the piston collision prevention control method. As described above, the sine wave command value as the resonance frequency determined by the spring and the gas spring constant; Vsin
Fsinc is given to the linear compressor 112 (step S
1). In step S29, the current piston value Pnow and the piston upper limit position set values Ptag1 and Ptag2 are read.
Further, the current rotational speed command Fannow of the blower and the target rotational speed command Fantag of the blower are read. Step S30
In step S31, the zone of the piston position is detected. The piston position is located between Ptag1 and Ptag2, and in step 32, the current rotational speed command FanVnow of the blower is compared with the target rotational speed command value Fantag of the blower. When the target rotational speed command is higher, the target motor current command value is reduced by ΔI in step S33, and the piston amplitude is reduced in advance.

FIG. 15 shows a tenth embodiment of the piston collision prevention control method. After the step S1, the current piston position Pnow, the upper limit position set value Ps of the piston, and the lower limit position set value Pdb are read. In step S34, the current piston value Pnow and the two lower limit position set values Pdtag
1, Pdtag2, and the current rotational speed command Fan of the blower
Vnow and a target rotation speed command value Fantag of the blower are read. Then, in steps S30 and S31, the zone of the piston position is detected, and the piston position becomes Pdtag1, Pdtag1, Pdtag1.
dtag2, and in step S32, the DC voltage Vdcnow is compared with the DC voltage set value Vdcm. When the DC voltage exceeds the set value, it is expected that the load will be suddenly reduced. -Reduce the motor current command value by ΔI and reduce the amplitude of the piston in advance.

FIG. 16 shows an eleventh embodiment of the piston collision prevention control method. As described above, the sine wave command value as the resonance frequency determined by the spring and the gas spring constant;
nFsinc is given to the linear compressor 112 (step S
1). In step S35, the current piston positions Pnow and 2
The two upper limit position set values Ptag1, Ptag2, the power supply voltage Vdcnow detected by the power supply voltage detection unit 103, and the power supply voltage set value Vdcm are read. In steps S30 and S31, the zone of the piston position is detected, and the piston position becomes Pt.
ag1 and Ptag2, and in step S32
Then, the power supply voltage Vdcnow is compared with the power supply voltage set value Vdcm, and when the power supply voltage exceeds the set value, that is, when the power supply voltage suddenly changes, the motor current command is reduced by ΔI in step S33, and the power supply voltage is reduced. Prevents collision of pistons even when sudden changes occur.

FIG. 17 shows the state of the upper limit position of the piston when the power supply voltage fluctuates by ± 10%. This indicates that the closer to the cylinder head side as the power supply voltage increases.

FIG. 18 shows a twelfth embodiment of the collision prevention control method. After the above-described step S1, in step S35, the current piston position Pnow and the two upper limit position set values Ptag
1. Read Ptag2, voltage Vdcnow detected by power supply voltage detection unit 103, and voltage set value Vdcm. Process S
At 30 and S31, the zone of the piston position is detected, the piston position is located between Ptag1 and Ptag2, and at step S32, the voltage Vdcnow and the voltage set value Vd are set.
cm, and when the voltage exceeds the set value, a DC component is added to -ΔIDC to instantaneously move the piston to the anti-compression side. Even when the voltage changes suddenly, the piston amplitude center is instantly offset to prevent collision. I do.

FIG. 19 shows a thirteenth embodiment of the piston collision prevention control method. After step S1, in step S35, the current value Pnow of the piston and the two upper limit position set values Ptag
1. Read Ptag2, current voltage Vdcnow, and voltage set value Vdcm data. In step S37, the speed Pspeed is calculated from the piston position information, and in step S38
The anti-collision setting speed Psp for performing anti-collision control based on the current speed Pspeed calculated in step S37.
Calculate tag. In steps S30 and S31, the zone of the piston position is detected, and the piston position is determined to be Ptag1, Ptag1.
If the actual speed Pspeed exceeds the collision prevention set speed Psptag in step S39 and the actual current speed Pspeed is exceeded in step S39, the current command of the linear motor is reduced by ΔI in step S33, and the piston amplitude of the piston is reduced earlier. Can be reduced.

FIG. 20 shows a fourteenth embodiment of the piston collision prevention control method. After step S1, in step S35, the current value Pnow of the piston and the two upper limit position set values Ptag
1, Ptag2, the current voltage Vdcnow, the set value Vdcm of the voltage, and the set value Exb of the opening / closing angle 40 of the pressure reducing expander are read. In steps S30 and S31, the zone of the piston position is detected, and the piston positions are determined to be Ptag1, Ptag2.
The current voltage Vdcnow is compared with the set value Vdcm of the voltage. When the voltage becomes higher than the set value, the current command of the linear motor is first reduced by ΔI in S33 to reduce the amplitude of the piston. Reduce. Next, in step S19, the discharge pressure is increased by narrowing the opening degree of the pressure reducing expander by ΔE1, and the piston is offset to the non-compression side to reduce the current, thereby reducing the load and shifting the amplitude center of the piston to the compression side. Can be prevented.

[0040]

According to the control method for preventing collision of a piston of a linear compressor according to the present invention, the stroke of the piston is reduced, and the top clearance of the piston is not changed. The piston can reliably be prevented from colliding with the cylinder head with reliability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a linear compressor according to one embodiment of the present invention.

FIG. 2 is a block diagram showing control of an air conditioner using the linear compressor.

FIG. 3 is a flowchart showing a piston collision prevention control method according to the first embodiment of the present invention.

FIG. 4 is a graph showing amplitude characteristics of a piston with respect to a driving frequency.

FIG. 5 is a flowchart showing a piston collision prevention control method according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing a piston collision prevention control method according to a third embodiment of the present invention.

FIG. 7 is a graph showing the displacement characteristic of the center of amplitude of the piston with respect to the degree of opening and closing of the linear expander.

FIG. 8 is a flowchart showing a piston collision prevention control method according to a fourth embodiment of the present invention.

FIG. 9 is a flowchart showing a piston collision prevention control method according to a fifth embodiment of the present invention.

FIG. 10 is a graph showing a displacement characteristic of a center of amplitude of a piston with respect to a DC current component.

FIG. 11 is a flowchart showing a piston collision prevention control method according to a sixth embodiment of the present invention.

FIG. 12 is a flowchart showing a piston collision prevention control method according to a seventh embodiment of the present invention.

FIG. 13 is a flowchart showing a piston collision prevention control method according to an eighth embodiment of the present invention.

FIG. 14 is a flowchart showing a piston collision prevention control method according to a ninth embodiment of the present invention.

FIG. 15 is a flowchart showing a piston collision prevention control method according to a tenth embodiment of the present invention.

FIG. 16 is a flowchart showing a piston collision prevention control method according to an eleventh embodiment of the present invention.

FIG. 17 is a graph showing a displacement characteristic of a compression side of a piston with respect to a power supply voltage fluctuation.

FIG. 18 is a flowchart showing a piston collision prevention control method according to a twelfth embodiment of the present invention.

FIG. 19 is a flowchart showing piston collision prevention control according to a thirteenth embodiment of the present invention.

FIG. 20 is a flowchart showing piston collision prevention control according to a fourteenth embodiment of the present invention.

FIG. 21 is a control block diagram showing a conventional linear compressor.

FIG. 22 is a flowchart showing piston collision prevention control showing a conventional example.

[Explanation of symbols]

 Reference Signs List 10 Cylinder 14 Discharge gas introduction path 14a Communication hole 14b Ring groove 14c Introduction hole 15 Through hole 20 Piston 22 Ball seat 23 Dynamic pressure groove 30 Connecting rod 31 Spherical end of connecting rod 32 Spherical end of connecting rod Opposite end 40 Movable part 41 Permanent magnet 42 Cylindrical holding member 50 Fixed part 51 Inner yoke 52 Outer yoke 53 Coil 53 60 Spring mechanism 61 Spring plate 80 Head cover 90 Support mechanism 91 Coil spring 100 Sealed container

Claims (14)

[Claims] A step of driving the linear compressor at a drive frequency that matches a drive frequency of the piston with a resonance frequency determined by a spring and a gas spring constant; and a current position of the piston and an upper limit position of the movement of the piston. Read the setting value,
Comparing the current position of the piston with an upper limit position set value of the piston, and when the current position of the piston exceeds the upper limit position set value of the piston, a drive frequency command higher or lower than a resonance frequency to the piston. Supplying a value to reduce the amplitude of the piston. 2. The linear compressor according to claim 1, wherein the upper limit position set value has a plurality of set values according to a difference between a top dead center and a top dead center reference value. Piston collision prevention control method. 3. When the current position of the piston exceeds the upper limit position set value of the piston, the resonance frequency is higher or higher than the larger upper limit position set value of at least two or more upper limit position set values. 3. The method according to claim 2, wherein a low frequency command value is supplied. 4. A control method for preventing collision of a piston of a linear compressor constituting a refrigeration cycle together with a condenser, a decompression expander, and an evaporator, wherein a drive frequency command value higher or lower than a resonance frequency is supplied to the piston. After the step of reducing the amplitude of the piston by controlling the opening degree of the decompressor and expanding the center of amplitude of the piston in the negative direction to bring the center of amplitude of the piston closer to the anti-compression side. The control method for preventing a piston from colliding in a linear compressor according to claim 1, wherein: 5. When the current position of the piston exceeds the upper limit position set value of the piston, the higher or lower the upper limit position set value of at least two or more upper limit position values, the higher or lower the resonance frequency. The method according to claim 4, further comprising a step of supplying a command value and further narrowing an opening degree of the pressure reducing expander. 6. A step of supplying a direct current to a piston to drive a linear compressor, reading a current position of the piston and upper and / or lower limit position set values of the piston, and reading a current position of the piston and a position of the piston. Comparing the current position of the piston with the upper or lower limit set value of the piston, and controlling the DC current component to move the center of amplitude of the piston in the negative direction or the positive direction. Offsetting in the direction to move the piston closer to the compression side or closer to the anti-compression side. 7. When the current position of the piston exceeds a set value of the upper limit position of the piston, the DC current component is controlled to be negative to offset the center of amplitude of the piston in the negative direction. Item 2. A control method for preventing piston collision of a linear compressor according to Item 1. 8. When the current position of the piston exceeds the lower limit position set value of the piston, the DC current component is controlled to be positive to offset the center of amplitude of the piston in the positive direction. Item 2. A control method for preventing piston collision of a linear compressor according to Item 1. 9. When the current position of the piston exceeds an upper or lower limit position set value of the piston, a plurality of upper and / or lower limit position set values of the piston is provided. The piston of the linear compressor according to claim 6, further comprising a step of further increasing or decreasing the DC component of the linear motor input current as the value exceeds the upper limit or lower limit position set value of the larger value. Collision prevention control method. 10. A control method for preventing collision of a piston of a linear compressor constituting a refrigeration cycle together with a condenser, a decompressor and an evaporator, the method comprising controlling discharge pressure to drive the linear compressor. Reading the current piston position and the upper and / or lower limit position set value of the piston, and comparing the current position of the piston with the upper or lower limit set value of the piston; and When the upper limit or lower limit position is exceeded, the opening / closing degree of the pressure reducing expander is controlled to offset the amplitude center of the piston in the negative direction or the positive direction to shift the amplitude center of the piston to the compression side or the anti-compression side. A method for preventing piston collision of a linear compressor. 11. A control method for preventing collision of a piston of a linear compressor constituting a refrigeration cycle together with a condenser, a decompression expander, and an evaporator, comprising: a step of driving the linear compressor; Read the plurality of upper or lower limit position set values of the piston and the current rotational speed and set value of the condenser blower or the evaporator blower, the current position of the piston between at least two upper or lower limit set values And reducing the current value of the motor when the current rotation speed of the blower is higher than a rotation setting value. 12. A step of controlling a power supply voltage to drive the linear compressor, reading a current position of the piston, a plurality of upper limit position set values of the piston, a current voltage and a voltage set value, and reading the current position of the piston. Is located between at least two upper limit position set values, and when the current voltage is higher than the voltage set value, reducing the voltage to reduce the motor current value. Collision prevention control method. 13. A step of controlling a power supply voltage to drive the linear compressor, reading a current position of the piston, a plurality of upper limit position set values of the piston, a current voltage and a voltage set value, and reading the current position of the piston. Is located between at least two upper limit position set values, and when the current voltage is higher than the voltage set value, a step of offsetting the voltage to the negative side is provided. Method. 14. The apparatus according to claim 1, further comprising a step of calculating a differential speed from the position information of the piston and calculating a set speed for performing the collision prevention control based on a current speed. Control method for preventing piston collision of linear compressor.