JPH09151843A - Linear compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear compressor to open and close a suction valve and a delivery valve by a minimum stroke amount on all operation conditions. SOLUTION: By reciprocating a piston 3 in a cylinder 2 with the aid of a linear motor 7, compression gas is generated in a compression chamber 4 and a space on the back side of the piston 3 is separated into a back pressure space 14 and a buffer space 15 for controlling a neutral position by a piston mounting plate 13. By elevating the piston mounting plate 13 through opening and closing of solenid valves 16 and 17, high pressure gas in the buffer space 15 for controlling a neutral position is controlled and the neutral position of the piston 3 is changed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view of a conventional linear compressor. In FIG. 6, the linear compressor 1 is
It includes a cylinder chamber 2 formed by a cylindrical cylinder wall and having upper and lower ends opened, and a piston 3 inserted so as to reciprocate in the cylinder chamber 2. A compression chamber 4 is formed above the cylinder chamber 2 so as to face the head of the piston 3. A suction valve 5 and a discharge valve 6 that open and close according to the gas pressure in the compression chamber 4 are provided above the compression chamber 4.

The piston 3 is driven by a linear motor 7 to reciprocate. The linear motor has a cylindrical bobbin 8
And a coil 9 wound around the bobbin 8 and a ring-shaped magnet 10 arranged so as to face the coil 9. The piston 3 is fixed to the center of the bobbin 8, and the bobbin 8 is supported by the casing 12 by the spring 11.

In the linear compressor thus constructed, when AC power is supplied to the coil 9, a magnetic field as shown in FIG. 6 is generated in the bobbin 8, and the linear motor 7 causes the piston 3 to reciprocate. The reciprocating motion of the piston 3 causes the expanded gas to be sucked into the compression chamber 4 through the suction valve 5, compressed by the piston 3, and discharged through the discharge valve 6.

Since the thrust of the linear motor 7 shown in FIG. 5 is proportional to the energizing current, the stroke of the piston 3 moving up and down by the current can be freely controlled. Therefore, it is possible to perform capacity control only by controlling the excluded volume without using a frequency conversion device such as an inverter.

[0006]

However, when the stroke of the piston 3 is made too small in the case of low energy operation such as under low load, the pressure amplitude inside the compression space decreases, and the internal pressure is reduced by the suction valve 5. And, there arises a problem that the opening pressure of each discharge 6 is not reached. In this case, if an attempt is made to obtain the pressure required to open the suction valve 5 and the discharge valve 6, an unnecessary current will be supplied to the linear motor 7, and as a result, operating efficiency at low load will be obtained. Will get worse.

Therefore, the main object of the present invention is to control the neutral position of the piston so that the intake valve and the discharge valve can be opened and closed with a minimum stroke amount for all operating conditions, and efficient operation is possible. Is to provide a linear compressor capable of

[0008]

The invention according to claim 1 is
A linear compressor that reciprocates a piston in a cylinder by a linear motor to generate compressed gas, and separates a back pressure space and a buffer space by a mounting plate for fixing the piston to control the volume of the buffer space. As a result, the neutral position of the piston is made variable.

Therefore, according to the present invention, the neutral position of the piston can be controlled by controlling the volume of the buffer space and moving the mounting plate, and the suction valve and the discharge valve can be opened and closed with a minimum stroke amount. It can be carried out, and highly efficient operation becomes possible.

According to the second aspect of the invention, the volume of the buffer space is controlled by letting gas flow in and out of the buffer space.

[0011]

1 is a vertical sectional view of an embodiment of the present invention. In FIG. 1, the lower part of the casing 12 is partitioned by a piston mounting plate 13 into a back pressure space 14 and a neutral position control buffer space 15. Casing 1
A gas seal 22 is attached between the piston 2 and the piston mounting plate 13. The neutral position of the piston 3 can be controlled by moving the piston mounting plate 13 up and down to change the volume of the neutral position control buffer space 15.

The vertical movement of the piston 3 is performed by controlling the gas pressure in the buffer space 15 for neutral position control. That is, two solenoid valves 16 and 17 communicating with the neutral position control buffer space 15 are provided.
Guides the high-pressure gas stored in the high-pressure tank 18 to the neutral position control buffer space 15, and the solenoid valve 17 guides the high-pressure gas in the neutral position control buffer space 15 to the low-pressure tank 19. The high pressure tank 18 and the low pressure tank 19 each have a valve 2
0 and 21 are provided, the valve 20 guides the high pressure gas from the high pressure space inside the refrigerator to the high pressure tank, and the valve 21 guides the gas inside the low pressure tank to the low pressure space inside the refrigerator. Other than that, the linear motor 7, the suction valve 5, the discharge valve 6 and the like are configured in the same manner as in FIG. 6 described above.

FIG. 2 is a block diagram showing a control unit for vertically moving the piston 3 shown in FIG. In FIG. 2, the freezing temperature is detected by the sensor 30, the detection output is converted into a digital signal by the A / D converter 31, and the digital signal is input to the microcomputer 32. The microcomputer 32 controls the solenoid valves 16 and 17 shown in FIG. 1 via the drive circuit 33 by performing control based on the flowchart shown in FIG.

FIG. 3 shows a state in which high pressure gas is supplied to the neutral position control buffer space 15 to raise the piston mounting plate 13, and FIG. 4 shows a state in which high pressure gas is removed and the piston mounting plate 13 is lowered. 5 is a flowchart for explaining the operation of the piston neutral position control.

Next, the operation of the piston neutral position control will be described with reference to FIGS. When the sensor 30 detects that the freezing temperature is out of the set position, the microcomputer 32 determines whether the freezing capacity is insufficient. If the freezing capacity is insufficient, the input current flowing through the coil 9 is increased, and In the opposite case, the input current is reduced. Then, it is determined whether or not the pressure fluctuation is normal, that is, whether the suction valve 5 and the discharge valve 6 are normally opened and closed,
If not normal, it is determined whether the pressure amplitude is too small. If the pressure amplitude is small, as shown in FIG. 3, the solenoid valve 16 is opened to move the high pressure gas to the neutral position control buffer space 1.
5, and the piston mounting plate 13 is moved upward. On the contrary, if the pressure amplitude is large, as shown in FIG.
The solenoid valve 17 is opened, and the high pressure gas in the neutral position control buffer space 15 is caused to flow out to the low pressure tank 19 side. As a result, the neutral position of the piston is lowered, and the pressure amplitude can be reduced. By repeating this operation, the neutral position of the piston 3 can be controlled, and the suction valve 5 and the discharge valve 6 can be opened and closed with a minimum stroke amount. When the refrigerating capacity reaches the set value, the operation is continued.

In the above description, the high pressure gas is caused to flow into the neutral position control buffer space, and the piston mounting plate 1 is
Although 3 is moved, the piston mounting plate 13 may be moved using a drive mechanism such as a motor without being limited to this.

[0017]

As described above, according to the present invention, the neutral position of the piston can be changed by separating the back pressure space and the buffer space by the mounting plate for fixing the piston and controlling the volume of the buffer space. It is possible to open and close the intake valve and the discharge valve with a minimum stroke amount under all operating conditions, and efficient operation is possible.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a control unit according to the embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing a state in which high-pressure gas is caused to flow into the neutral position control buffer space.

FIG. 4 is a vertical cross-sectional view showing a state in which high-pressure gas in a buffer space for neutral position control is let out.

FIG. 5 is a flowchart for explaining the operation of the embodiment of the present invention;

FIG. 6 is a vertical sectional view of a conventional linear compressor.

[Explanation of symbols]

 1 Linear compressor 2 Cylinder 3 Piston 4 Compression chamber 5 Suction valve 6 Discharge valve 7 Linear motor 8 Bobbin 9 Coil 10 Magnet 11 Spring 12 Casing 13 Piston mounting plate 14 Back pressure space 15 Neutral position control buffer space 16, 17 Solenoid valve 18 High-pressure tank 19 Low-pressure tank 20,21 Valve 22 Gas seal 30 Sensor 31 A / D converter 32 Microcomputer

Claims (2)

[Claims] 1. A linear compressor that reciprocates a piston in a cylinder by a linear motor to generate compressed gas, wherein a back plate space and a buffer space are separated by a mounting plate for fixing the piston, A linear compressor, wherein the neutral position of the piston is changed by controlling the volume of the buffer space. 2. The linear compressor according to claim 1, wherein the volume of the buffer space is controlled by causing gas to flow in and out of the buffer space.