JP3177457B2 - Drive unit for linear compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a linear compressor, and more particularly to a driving device for a linear compressor in which a piston is reciprocated in a cylinder by a linear motor to generate compressed gas.

[0002]

2. Description of the Related Art In recent years, a linear compressor has been developed as a mechanism for compressing expanded refrigerant gas in a cooling device such as a refrigerator. In this linear compressor, a piston is reciprocated in a cylinder by a linear motor to perform gas compression.

[0003]

In such a linear compressor, high efficiency can be obtained when the phase of the drive current of the linear motor coincides with the speed of the piston, and the top clearance (the piston head and the inner wall of the cylinder) can be improved. The highest efficiency is obtained when the closest distance between the ends is maintained at a minimum value (about 0.1 mm).

Therefore, it is conceivable to control the frequency of the drive current so that the phase of the drive current of the linear motor coincides with the phase of the speed of the piston. However, a state in which the top clearance is kept small (for example, about 0.1 mm) If the frequency of the drive current is controlled in (2), there is a problem that the loss is improved and the amplitude of the piston increases, and the head of the piston collides with the end of the inner wall of the cylinder.

It is conceivable to control the amplitude of the piston so that the top clearance becomes a minimum value.
In a two-piston linear compressor, the actual neutral point of the piston may be shifted from the designed neutral point (origin) to the top dead center or the bottom dead center due to asymmetry of the valve or the like. In such a case, it is difficult to control both the top clearances of the two pistons with high accuracy.

SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide a linear compressor driving device capable of preventing a collision between a piston head and an end portion of an inner wall of a cylinder and achieving high efficiency.

It is another object of the present invention to provide a linear compressor drive device capable of controlling both top clearances of two pistons of a two-piston linear compressor with high accuracy.

[0008]

The invention according to claim 1 is
A driving device for a linear compressor that generates a compressed gas by reciprocating a piston in a cylinder by a linear motor, comprising a power source, a position command unit, a position detection unit, a current command unit, a speed detection unit, a phase difference detection unit, and a frequency. The control means is provided. The power supply outputs a drive current according to the current command value to the linear motor. The position command means commands the position of the piston in the cylinder according to a sine function. The position detecting means detects a position of the piston in the cylinder. The current command means generates a current command value such that the position detected by the position detection means matches the position commanded by the position command means, and supplies the current command value to the power supply. The speed detecting means detects a speed of the piston in the cylinder. The phase difference detecting means detects a phase difference between the current command value generated by the current command means and a value indicating the speed detected by the speed detecting means. The frequency control means controls the frequency of a sine function used by the position command means so that the phase difference detected by the phase difference detection means disappears.
Then, when controlling the frequency of the sine function used in the position command means by the frequency control means, at least one of the current command value generated by the current command means and the amplitude of the sine function is reduced to a predetermined ratio. Let it.

According to a second aspect of the present invention, there is provided a driving device for a linear compressor which generates a compressed gas by reciprocating a piston in a cylinder by a linear motor, comprising:
The apparatus includes a current command unit, an amplitude detection unit, a speed detection unit, a phase difference detection unit, an amplitude control unit, and a frequency control unit. The power supply outputs a drive current according to the current command value to the linear motor. The current command means generates a current command value according to a sine function and supplies the current command value to a power supply. The amplitude detecting means detects the amplitude of the piston in the cylinder. The speed detecting means detects a speed of the piston in the cylinder. The phase difference detecting means detects a phase difference between a current command value generated by the current command means and a value indicating the speed detected by the speed detecting means. The amplitude control means controls the amplitude of a sine function used in the current command means so that the amplitude detected by the amplitude detection means matches a predetermined target value. The frequency control means controls the frequency of the sine function used in the current command means so that the phase difference detected by the phase difference detection means disappears. When the frequency of the sine function is controlled by the frequency control means, the amplitude of the sine function used in the current command means is reduced to a predetermined ratio.

[0010]

[0011]

According to a third aspect of the present invention, the shift amount detecting means and the shift amount control means are further provided in the first aspect. The shift amount detecting means detects a shift amount of the neutral point of the piston from the origin based on the detection result of the position detecting means. The shift amount control means controls the shift amount of the sine function used by the position command means so that the shift amount detected by the shift amount detection means disappears.

According to a fourth aspect of the present invention, an amplitude detecting means and an amplitude controlling means are further provided in the first or third aspect of the present invention. The amplitude detecting means detects a top dead center side amplitude between the top dead center and the origin of the piston and a bottom dead center side amplitude between the bottom dead center and the origin of the piston based on the detection result of the position detecting means. . The amplitude control means includes a sine function used by the position command means such that a larger one of the top dead center side amplitude and the bottom dead center side amplitude detected by the amplitude detection means matches a predetermined target value. , And at least one of the current command value generated by the current command means.

According to a fifth aspect of the present invention, a shift amount detecting means and a shift amount controlling means are further provided in the second aspect of the present invention. The shift amount detecting means detects a shift amount of the neutral point of the piston from the origin based on the detection result of the position detecting means. The shift amount control means controls the shift amount of the sine function used in the current command means so that the shift amount detected by the shift amount detection means disappears.

In the invention according to claim 6, the amplitude detecting means according to claim 2 or 5 is arranged such that the amplitude detecting means detects the top dead center between the top dead center of the piston and the origin based on the detection result of the position detecting means. The amplitude control means detects the bottom amplitude and the bottom dead center side amplitude between the bottom dead center and the origin of the piston, and the amplitude control means detects any one of the top dead center side amplitude and the bottom dead center side amplitude detected by the amplitude detection means. The amplitude of the sine function used in the current command means is controlled so that the larger value is equal to a predetermined target value.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 is a block diagram showing a configuration of a driving device 2 of a linear compressor 1 according to a first embodiment of the present invention.

In FIG. 1, the driving device 2 includes a power supply 3, a position sensor 4, and a control device 5. Power supply 3
The drive current I is supplied to the linear motor of the linear compressor 1. The position sensor 4 directly or indirectly detects the position of the piston of the linear compressor 1 and outputs an electric signal Pa corresponding to the position of the piston to the control device 5. As the position sensor 4, for example, a laser displacement meter is used. The control device 5 outputs a control signal φc corresponding to the output Pa of the position sensor 4 to the power supply 3, and controls the output current I of the power supply 3.

FIG. 2 is a sectional view showing the structure of the linear compressor 1. 2, the linear compressor 1 includes two cylinders 11a and 11b provided at an upper end and a lower end of a cylindrical casing 10, respectively.
And 2 inserted into the cylinders 11a and 11b, respectively.
Pistons 12a and 12b,
a, 12b and two compression chambers 13a, 13b formed at the inner wall ends of the cylinders 11a, 11b, and open / close in accordance with the gas pressure in the compression chambers 13a, 13b, respectively.
Set of suction valves 14a, 14b and discharge valve 15
a, 15b.

The two pistons 12a and 12b are provided at one end and the other end of one shaft 16, respectively. The shaft 16 is made up of the casing 10 and the cylinders 11a, 11b by two sets of linear ball bearings 17a, 17b and coil springs 18a, 18b.
It is supported so that it can reciprocate inside.

The linear compressor 1 includes a linear motor 20 for reciprocating the shaft 16 and the pistons 12a and 12b. The linear motor 20 is a voice coil motor, and includes a fixed portion including the yoke portion 10a and the permanent magnet 21, and a movable portion including the coil 23 and the cylindrical support member 24. Yoke part 10a
Constitutes a part of the casing 10. Permanent magnet 2
1 is provided on the inner peripheral wall of the yoke part 10a. One end of the support member 24 is reciprocally inserted between the permanent magnet 21 and the outer peripheral wall of the cylinder 11b, and the other end is fixed to the center of the shaft 16. The coil 23 is provided to face the permanent magnet 21 at one end of the support member. The power supply 3 and the coil 23 are connected via a coil spring-shaped electric wire 25.

This linear compressor 1 has a piston 1
It has a resonance frequency determined by the weights of the shafts 2a, 12b, the shaft 16, the coil 23, and the support member 24, the gas spring constants of the compression chambers 13a, 13b, the coil springs 18a, 18b, and the like. The resonance frequency is usually set near the frequency of commercial power (for example, 60 Hz). By driving the linear motor 20 at this resonance frequency, compressed gas can be generated with high efficiency in the upper and lower two compression chambers 13a and 13b.

FIG. 3 is a block diagram showing a configuration of a main part of control device 5 shown in FIG. 3, the control device 5 includes a position command value generation unit 30, a position / speed control unit 31, a current command value generation unit 32, a position / speed detection unit 33,
It includes a vertical dead center detector 34, a current / velocity phase difference detector 35, a current gain controller 36, an amplitude neutral position controller 37, and a frequency controller 38.

The position / velocity detecting section 33 includes a piston 12
The output Pa of the position sensor 4 is sampled at a sampling period (for example, 150 μsec) sufficiently smaller than the oscillation period of the a and 12b, the sampled value is A / D-converted to generate the current position value Pnow, and the current position value is obtained. The current speed value Vnow is obtained by differentiating Pnow.

The upper and lower dead center detector 34 detects a top dead center between the top dead center and the origin of the pistons 12a and 12b based on the maximum and minimum values of the current position value Pnow generated by the position / speed detector 33. The point-side amplitude and the amplitude at the bottom dead center between the bottom dead center and the origin are detected. 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 value Pref is completed, that is, when the position command value Pref passes through the zero cross point.

The current / speed phase difference detector 35 detects a phase difference between the current speed value Vnow generated by the position / speed detector 33 and the current command value Iref generated by the current command value generator 32. The detection of the phase difference is based on the current position value Pnow.
Is completed, ie, the current position value Pno
This is performed each time w passes through the zero cross point.

The position command value generating section 30 stores a sine table, an amplitude A, an angular frequency ω, a shift amount B, and a formula Pref = A sin ωt + B (sine function) stored in a memory.
The position command value Pref is generated based on the above, and the generated position command value Pref is given to the position / speed control unit 31.

The position / speed control unit 31 calculates a deviation Pr between the position command value Pref generated by the position command value generation unit 30 and the current position value Pnow generated by the position / speed detection unit 33.
The speed command value Vref is generated based on the ef-Pnow, and the speed command value Vref and the position / speed detection unit 33 are further generated.
Vref-V from the current speed value Vnow generated in
The speed control value Vc is generated based on now.

The current command value generator 32 includes a speed control value Vc generated by the position / speed controller 31 and a current gain Gi.
And the current command value Ir based on the formula Iref = GiVc.
ef, and further, the current command value Iref is
is converted to c and supplied to the power supply 3. The control of the output current I of the power supply 3 is performed by, for example, a PWM method or a PAM method.

The current gain control unit 36 compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit 34, and selects one of the top dead center side amplitude and the bottom dead center side amplitude. Is larger than the maximum amplitude current value Anow, and this maximum amplitude current value Anow is a predetermined maximum amplitude target value Ar.
The value of the current gain Gi used in the current command value generation unit 32 is controlled for each cycle of the vibration of the pistons 12a and 12b so as to match ef. In addition, the current gain control unit 36 controls the current / speed phase difference detection unit 3 once every several hundred (for example, 300) cycles of the vibration of the pistons 12a and 12b.
It is determined whether or not the phase difference detected in step 5 exceeds a predetermined allowable value, and if so, the value of the current gain Gi used in the current command value generating section 32 is reduced by several percent. In this way, by controlling the maximum amplitude in addition to the position / speed control by the position / speed controller 31 and reducing the current gain Gi by several percent prior to the frequency control, the heads of the pistons 12a and 12b and the cylinder 11 are controlled.
It is possible to reliably avoid the collision of the a and 11b with the end of the inner wall.

The amplitude neutral position control unit 37 compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit 34, and determines the difference between the top dead center side amplitude and the bottom dead center side amplitude. The shift amount B used by the position command value generation unit 30 is controlled so as to be smaller each time one cycle of the position command value Pref is completed. That is, if the top dead center side amplitude is larger than the bottom dead center side amplitude, the amplitude neutral position control unit 37 corrects the shift amount B to the negative side (downward), and the top dead center side amplitude becomes lower. If the amplitude is smaller than the dead center side amplitude, the shift amount B is corrected to the positive side (upward). Normally, the shift amount B is substantially constant due to the characteristics of the device such as valve asymmetry, so that the control amount per shift amount B is set to a small value (for example, 1 μm). By controlling the shift amount B in this way,
The top clearance between the two pistons 12a and 12b can be controlled equally accurately.

The frequency controller 38 determines whether or not the phase difference detected by the current / speed phase difference detector 35 exceeds a predetermined allowable value. The angular frequency ω used in the position command value generator 30 is corrected. The correction of the phase difference is performed almost simultaneously with the reduction of the current gain Gi by several percent by the current gain control unit 36. Thereby, the efficiency is improved by correcting the phase difference, and the heads of the pistons 12a, 12b are prevented from colliding with the inner wall ends of the cylinders 11a, 11b due to the increased amplitude of the pistons 12a, 12b.

FIGS. 4 and 5 are flowcharts showing the operation of the control device 5 shown in FIG. The operation of the linear compressor 1 and the driving device 2 thereof shown in FIGS. 1 to 3 will be described according to this flowchart.

First, the position command value P
ref is generated, the speed / control value Vc is generated by the position / speed control unit 31, and the control signal φc is generated by the current command value generation unit 32.
Is generated. Power supply 3 to coil 2 of linear motor 20
When an electric current is supplied to 3, the movable portion of the linear motor 24 starts reciprocating motion, thereby starting generation of compressed gas.

In step S1, the position / speed detector 3
3, the position data, that is, the output Pa of the position sensor 4
Is read, and in step S2, the position / speed detection unit 33 calculates the current position value Pnow and the current speed value Vnow.

In step S3, speed control is performed by the position / speed controller 31. That is,
The speed control unit 31 calculates the speed command value Vref and the current speed value V
The speed control value Vc is generated based on the deviation from the current value and given to the current command value generation unit 32.

In step S4, the current command value generator 3
2, a current command value Iref, which is a product of the speed control value Vc and the current gain Gi, is generated. In step S5, current command data corresponding to the current command value Iref, that is, a control signal φc is transmitted to the power supply 3 from the current command value generation unit 32. Is output.

In step S6, the count value of a first counter (not shown) included in the control device 5 is incremented (+1), and in step S7, the count value of the first counter reaches a set value (for example, 3). It is determined whether or not it is.

If the count value of the first counter has reached the set value in step S7, the amplitude A and the angular frequency ω are set in step S8 based on the position correction amount and the frequency set value in the position command value generation unit 30. Generated
Further, based on the sine table, the amplitude A, the shift amount B and the angular frequency ω, the position command value Pref = A sin ωt
+ B is generated. In step S9, position control is performed by the position / speed control unit 31. That is, the position / speed control unit 31 generates the speed command value Vref based on the deviation between the position command value Pref and the current position value Pnow. After the position control is completed, the first
The count value of the counter is reset.

If the count value of the first counter has not reached the set value in step S7, step S8
Steps S10 are not executed.

Next, in step S11, it is determined whether one cycle of the position command value Pref has been completed.

In step S11, the position command value Pre
If it is determined that one cycle of f has been completed, the upper and lower dead center detection unit 34 determines the piston 12 based on the maximum value and the minimum value of the current position value Pnow in step S12.
The top dead center side amplitude and the bottom dead center side amplitude of a and 12b are detected.

In step S13, the magnitude relationship between the top dead center side amplitude and the bottom dead center side amplitude is compared. If the top dead center side amplitude is larger than the bottom dead center side amplitude, the amplitude neutral position control is performed in step S14. The negative correction amount is set as the correction amount of the shift amount B by the unit 37, and the top dead center side amplitude is set as the current maximum amplitude Anow in step S15.

As a result of the magnitude comparison in step S13,
If the bottom dead center side amplitude is larger than the top dead center side amplitude,
In step S16, a positive correction amount is set as the correction amount of the shift amount B by the amplitude neutral position control unit 37, and in step S17, the bottom dead center side amplitude is set as the maximum amplitude current value Anow.

In step S18, the current gain Gi is controlled and set by the current gain controller 36 so that the current maximum amplitude Anow matches the maximum amplitude target value Aref. The maximum value and the minimum value of the current value Pnow are reset.

In step S11, the position command value Pre
If it is not determined that one cycle of f has been completed, steps S12 to S19 are not executed.

Next, at step S20, the top dead center detecting section 34
Detects and holds the maximum value and the minimum value of the current position value Pnow. In step S21, the current / speed phase difference detector 35 determines whether one cycle of the current position value Pnow has been completed.

In step S21, the current position value Pnow is set to 1
If it is determined that the cycle has been completed, step S2
In 2, the current / speed phase difference detection unit 35 detects the phase difference between the current command value Iref and the current speed value Vnow.

Next, in step S23, the count value of the second counter (not shown) is incremented, and in step S24, it is determined whether or not the count value of the second counter has reached the set value (300).

If it is determined in step S24 that the count value of the second counter has reached the set value, in step S25 the current command value Iref and the current speed value V
It is determined whether or not the now phase difference is within an allowable value.

If it is determined in step S25 that the value is not within the allowable value, the frequency control unit 38 controls the frequency of the position command value Pref in step S26.
The setting is performed, and in step S27, the current gain Gi of the current command value Iref is
Is reduced by several percent.

If it is determined in step S25 that the phase difference is within the allowable value, steps S26 and S27
Is not executed.

Next, in step S28, the count value of the second counter is reset. If it is determined in step S21 that one cycle of the current position value Pnow has not been completed, steps S22 to S28 are not executed. If it is determined in step S24 that the count value of the second counter has not reached the set value, steps S25 to S28 are not performed.

Next, in step S29, it is determined whether or not the control has been completed. If it is determined that the control has been completed, the control is completed. If it is determined that the control has not been completed, the process returns to step S1 again.

In this embodiment, the current command value Iref
When the frequency of the position command value Pref is controlled so that the phase difference between the current command value I
The current gain Gi of ref = GiVc is reduced by several percent. Therefore, even if the loss is improved by controlling the frequency of the position command value Pref and the amplitude of the pistons 12a and 12b is increased, the heads of the pistons 12a and 12b are moved to the cylinder 1 position.
There is no collision with the inner wall ends of 1a and 11b.

The current gain Gi of the current command value Iref is controlled such that the larger of the top dead center side amplitude and the bottom dead center side amplitude of the pistons 12a and 12b is located at the maximum amplitude target value Aref. Even if the actual neutral point of the pistons 12a and 12b deviates from the designed neutral point (origin),
The heads of the pistons 12a, 12b are
There is no collision with the end of the inner wall 1b.

The shift amount B of the actual neutral point of the pistons 12a and 12b from the origin is detected, and the shift amount B
Since the shift amount B of the position command value Pref is controlled so as to eliminate the error, both head clearances of the two pistons 12a and 12b can be controlled equally accurately.

In this embodiment, the phase difference between the current command value Iref and the current speed value Vnow is detected by the current / speed phase difference detection section 35, and the frequency of the position command value Pref is changed so that the phase difference disappears. However, the present invention is not limited to this. The current command value Iref and the current position value P
Alternatively, the frequency of the position command value Pref may be controlled so that the phase difference of now is detected and the phase difference becomes 90 °.

[Second Embodiment] FIG. 6 is a block diagram showing a configuration of a linear compressor driving device according to a second embodiment of the present invention.

In FIG. 6, the driving device of this linear compressor is different from that of the first embodiment in that the control device 5 is replaced by a control device 40 and the position command value Pref is replaced with the current gain Gi of the current command value Iref. The point is that the amplitude A is controlled.

The control unit 40 is obtained by replacing the current gain control unit 36 of the control unit 5 with a position command value amplitude control unit 41. The position command value amplitude control unit 41 compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit 34, and selects one of the top dead center side amplitude and the bottom dead center side amplitude. The larger one is set as the maximum amplitude current value Anow, and this maximum amplitude current value Anow is set to a predetermined maximum amplitude target value Ar.
The value of the amplitude A used in the position command value generation unit 30 is controlled for each cycle of the vibration of the pistons 12a and 12b so as to match ef. The position command value amplitude control unit 41
Is equivalent to hundreds of vibrations of the pistons 12a and 12b (for example, 3
00) Once in a cycle, it is determined whether or not the phase difference detected by the current / speed phase difference detection unit 35 exceeds a predetermined allowable value. The value of the amplitude A is reduced by several percent.

FIGS. 7 and 8 are flowcharts showing the operation of the linear compressor driving device shown in FIG.

7 and FIG. 8, this flowchart is different from the flowcharts of FIG. 4 and FIG.
Steps S4 ', S8', S18 ', and S27' are executed instead of steps S4, S8, S18, and S27, respectively.

That is, in step S 4 ′, the current command value generator 32 controls the speed control value Vc and the current gain G
A current command value Iref, which is a product of i, is calculated. This current gain Gi is a constant. In step S8 ',
Position command value Pref = A by position command value generation unit 30
sinωt + B is generated. Here, each of the amplitude A, the angular frequency ω, and the shift amount B is a variable.

In step S18 ', the amplitude A of the position command value Pref is controlled and set by the position command value amplitude controller 41 such that the current maximum amplitude Anow of the pistons 12a and 12b matches the maximum amplitude target value Aref. . In step S27 ', the amplitude A of the position command value Pref is reduced by several percent by the position command value amplitude control unit 41. Other configurations and operations are the same as those of the first embodiment, and therefore description thereof will not be repeated.

In this embodiment, the same effect as in the first embodiment can be obtained. [Third Embodiment] FIG. 9 is a block diagram showing a configuration of a driving device for a linear compressor according to a third embodiment of the present invention.

In FIG. 9, the driving device of this linear compressor differs from that of the first embodiment in that the control device 5 is replaced by a control device 42 to simplify the configuration.

The control unit 42 is obtained by removing the position / speed control unit 32 of the control unit 5 and replacing the position command value generation unit 30 with a current command value basic value generation unit 43. The current command value basic generator 43 converts the sine table stored in the memory, the amplitude A ', the angular frequency ω', the shift amount B ', and the formula Ic = A'sin ω't + B' (sine function) into A current basic value Ic is generated based on the current value, and the generated current basic value Ic is provided to the current command value generation unit 32.

The current command value generator 32 generates a current command value Iref based on the current basic value Ic generated by the current command value basic value generator 43, the current gain Gi, and the equation Iref = GiIc. Further, current command value Iref is converted into control signal φc and applied to power supply 3.

The amplitude neutral position control unit 37 calculates the position command value Pr.
controlling the shift amount B 'of current basic value Ic instead of the shift amount B of ef, frequency control unit 38 is position instruction value Pref
Is controlled instead of the frequency of the current basic value Ic.

[0070] FIGS. 10 and 11 are flow charts showing the operation of the linear motor of the drive apparatus shown in FIG.

In step S 31, the position / speed detector 33 outputs position data, that is, the output P of the position sensor 4.
a is read, and in step S32, the position / speed detection unit 33 calculates the current position value Pnow and the current speed value Vnow.

In step S33, the current command value generator 32 generates a current command value Iref which is the product of the current basic value Ic and the current gain Gi. In step S34, the current command value generator 32 responds to the current command value Iref. Current command data, that is, control signal φc is output to power supply 3.

Next, in step S35, the amplitude A 'and the angular frequency ω' are generated by the current command value basic value generation unit 43 based on the position correction amount and the frequency set value, and further, the sine table, the amplitude A ', and the shift amount Based on B ′ and angular frequency ω ′, basic current value Ic = A′sin ω′t +
B 'is generated.

Steps S36 to S54 are the same as steps S11 to S29 shown in FIGS. 4 and 5, and therefore description thereof will not be repeated.

In this embodiment, the same effects as in the first embodiment can be obtained, and the configuration of the control device can be simplified.

Note that, in this embodiment, the present invention
Although an example in which the present invention is applied to the piston type linear compressor 1 has been described, the one of the present invention in which the amplitude is temporarily reduced when controlling the frequency is also effective for the one-piston type linear compressor.

FIG. 12 is a sectional view showing the structure of the one-piston linear compressor 50. 12, a linear compressor 50 includes a cylinder 51, a piston 52 reciprocally fitted in the cylinder 51, a compression chamber 53 formed by a head of the piston 52 and an end of an inner wall of the cylinder 51. A suction valve 54 and a discharge valve 50 that open and close according to the gas pressure of the compression chamber 53 are provided. Further, the linear compressor 50 includes a piston 5
2 includes a linear motor 56 for reciprocating the piston 2 and a piston spring 61 for supporting the piston 52 reciprocally. The linear motor 56 has a cylindrical yoke 57
And stators 58 and 59 having wound coils and a movable body 60 having a cylindrical permanent magnet. The yoke portion 57 is provided concentrically with the cylinder 51, and one end thereof is joined to one end of the cylinder 51. The stator 58 is provided on the outer peripheral wall of the cylinder 51, and the stator 59 is provided on the inner peripheral wall of the yoke 57. The movable body 60 includes the stators 58 and 59.
Between the piston 52 and one end thereof.
At one end. The peripheral portion of the piston spring 61 is fixed to the other end surface of the yoke portion 57, and the central portion is
2 is fixed to one end.

The piston 52 has a resonance frequency determined by the weight of the piston 52 and the movable body 60, the spring constant of the gas spring based on the pressure fluctuation of the gas in the compression chamber 53, the spring constant of the piston spring 61, and the like. A drive current I having a resonance frequency is supplied from the power supply 3 to the coils of the stators 58 and 59 of the linear motor 56.

These parts 51 to 61 are soundproof and
It is housed in a casing 63 via a mount spring 62 for vibration isolation.

From the power supply 3 to the stator 5 of the linear motor 56
When the drive current I is supplied to the coils 8 and 59, an electromagnetic force acts on the permanent magnet of the movable body 60, and the movable body 60 and the piston 52 reciprocate. By the reciprocating motion of the piston 52, the expansion gas is sucked into the compression chamber 53 via the suction valve 54, and the compressed gas generated in the compression chamber 53 is discharged via the protruding valve 55.

[0081]

As described above, according to the first aspect of the present invention, the position command means commands the position of the piston according to a sine function, and the current command means controls the current command so that the detected position value matches the position command value. The power supply outputs a drive current corresponding to the current command value to the linear motor. When the phase difference between the current command value and the piston speed exceeds the allowable value, the frequency control means reduces at least one of the current command value and the sine function to a predetermined ratio and eliminates the phase difference. So that the frequency of the sine function is controlled. Therefore, during the frequency control, the amplitude of the piston once decreases, so that even if the efficiency is improved by controlling the frequency, the amplitude of the piston increases and the piston head does not collide with the end of the inner wall of the cylinder.

In the invention according to claim 2, the current command means generates a current command value according to a sine function, and the amplitude control means controls the amplitude of the sine function so that the detected amplitude of the piston matches the target value. The power supply outputs a drive current according to the current command value to the linear motor. Then, when the phase difference between the current command value and the piston speed exceeds the allowable value, the frequency control means reduces the amplitude of the sine function to a predetermined ratio and changes the frequency of the sine function so that the phase difference disappears. Control. Therefore, the same effect as that of the first aspect can be obtained, and the configuration can be simplified.

According to the third aspect of the invention, the amount of shift of the neutral point of the piston from the origin can be eliminated, and the head of the piston can be prevented from colliding with the end of the inner wall of the cylinder. Also, even if the linear motor is a two-piston type,
Both head clearances of the two pistons can be controlled equally accurately.

In the invention according to claim 4, even if the neutral point of the piston deviates from the origin, the head of the piston does not collide with the end of the inner wall of the cylinder.

According to the fifth aspect of the invention, the same effects as those of the third aspect of the invention can be obtained, and the structure can be simplified.

According to the sixth aspect of the invention, the same effects as those of the fourth aspect of the invention can be obtained, and the structure can be simplified.

[0087]

[0088]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a linear compressor driving device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of the linear compressor shown in FIG.

FIG. 3 is a block diagram showing a configuration of a main part of the control device shown in FIG. 1;

FIG. 4 is a flowchart illustrating an operation of the control device illustrated in FIG. 3;

FIG. 5 is a partial view of FIG. 4;

FIG. 6 is a block diagram showing a main part of a control device of a linear compressor driving device according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of the control device shown in FIG. 6;

FIG. 8 is a partial view of FIG. 7;

FIG. 9 is a block diagram showing a configuration of a main part of a control device of a linear compressor drive device according to Embodiment 3 of the present invention.

10 is a flowchart showing the operation of the control device shown in FIG.

FIG. 11 is a partial view of FIG. 10;

FIG. 12 is a cross-sectional view showing an improved example of the driving device for the linear compressor shown in FIG.

[Explanation of symbols]

 1,50 Linear compressor 2 Drive unit 3 Power supply 4 Position sensor 5,40,42 Control unit 11a, 11b, 51 Cylinder 12a, 12b, 52 Piston 20,56 Linear motor 30 Position command value generation unit 31 Position / speed control unit 32 Current command value generation unit 33 Position / speed detection unit 34 Vertical dead center detection unit 35 Current / speed phase difference detection unit 36 Current gain control unit 37 Amplitude neutral position control unit 38 Frequency control unit 41 Position command value amplitude control unit 43 Current command Value basic value generator

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-51-57009 (JP, A) JP-A-3-3984 (JP, A) JP-A-8-247025 (JP, A) US Pat. , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 49/06 341 F04B 35/04 H02P 7/00 101

Claims (6)

(57) [Claims] 1. A drive device for a linear compressor which generates a compressed gas by reciprocating a piston in a cylinder by a linear motor, wherein the drive source outputs a drive current corresponding to a current command value to the linear motor, according to a sine function. Position instructing means for instructing the position of the piston in the cylinder, position detecting means for detecting the position of the piston in the cylinder, and the position detected by the position detecting means is instructed by the position instructing means. Current command means for generating the current command value to match the position and applying the current command value to the power supply; speed detection means for detecting the speed of the piston in the cylinder; and a current command value generated by the current command means. Phase difference detection for detecting a phase difference from a value indicating the speed detected by the speed detecting means. Output means and the position command means so that the phase difference detected by the phase difference detection means is eliminated.
Frequency controlling the frequency of the sine function used in the stage
Control means, which is used in the position command means by the frequency control means.
When controlling the frequency of the sine function, the current command
Command value generated by the means and the amplitude of the sine function
At least one is reduced to a predetermined rate
A driving device for a linear compressor, characterized in that: 2. A drive device for a linear compressor which generates a compressed gas by reciprocating a piston in a cylinder by a linear motor, wherein the power source outputs a drive current according to a current command value to the linear motor, according to a sine function. Current command means for generating the current command value and applying the current command value to the power supply; amplitude detection means for detecting the amplitude of the piston in the cylinder; speed detection means for detecting the speed of the piston in the cylinder; Phase difference detecting means for detecting a phase difference between a current command value generated by a current command means and a value indicating a speed detected by the speed detecting means; an amplitude detected by the amplitude detecting means being a predetermined target Amplitude control means for controlling the amplitude of the sine function used in the current command means so as to match the value, and No phase difference detected by the phase difference detecting means
The sine function used in the current command means so that
Frequency control means for controlling the frequency of the current command means by the frequency control means.
When controlling the frequency of the sine function, the sine function
Characterized by reducing the amplitude of the
A linear compressor drive device. 3. A method according to claim 1, wherein said position detecting means detects a position of said position detecting means.
To detect the amount of shift of the neutral point of the piston from the origin
Shift amount detecting means, and the shift amount detecting means
Therefore, the position finger is moved so that the detected shift amount disappears.
Controlling the shift amount of the sine function used in the command means
The drive device for a linear compressor according to claim 1, further comprising a shift amount control unit . 4. A method according to claim 1, wherein said position detecting means detects a result of said detecting operation.
The top dead center side amplitude between the top dead center of the piston and the origin,
Check the bottom dead center side amplitude between the bottom dead center of the piston and the origin.
Output amplitude detecting means, and the amplitude detecting means
One of the detected top dead center amplitude and bottom dead center amplitude
The larger the difference, the more it matches the predetermined target value.
The amplitude and the amplitude of the sine function used in the position command means.
And the current command value generated by the current command means.
Claims: It is provided with an amplitude control means for controlling at least one of them.
4. The driving device for a linear compressor according to 1 or 3 . 5. A method according to claim 1, wherein said position detection means detects a result of said detection.
To detect the amount of shift of the neutral point of the piston from the origin
Shift amount detecting means, and the shift amount detecting means
Therefore, the current finger is controlled so that the detected shift amount disappears.
Controlling the shift amount of the sine function used in the command means
3. The driving device for a linear compressor according to claim 2, further comprising a shift amount control unit . 6. The apparatus according to claim 6, wherein said amplitude detecting means is provided on said piston.
Top dead center amplitude between dead center and origin and bottom dead center of the piston
And the lower dead center side amplitude between the origin and the origin, and the amplitude control means detects the amplitude by the amplitude detection means.
One of the top and bottom dead center amplitudes
I sea urchin said that the larger matches the predetermined target value
Controlling the amplitude of the sine function used in the current command means.
The driving device for a linear compressor according to claim 2 or 5, wherein