KR20090042563A - Reciprocating compressor - Google Patents

Abstract

A reciprocating compressor is provided to supply AC power to the linear motor with less inverter switches and implement the AC power supply path with a DC link and inverter switches, thereby simplifying the circuit configuration. A reciprocating compressor comprises a piston, a cylinder, a coil part(205) which is equipped in the cylinder to reciprocate the piston and a power supply unit supplying the power to the coil part. The power supply unit includes a rectifier(202) rectifying the AC voltage supplied from an AC power supply(201), a DC link(203) stabilizing the rectified voltage, and a switch part(204) consisting of a pair of inverter switches which are connected to the DC link and supply the stabilized power to the coil part.

Description

Reciprocating Compressor {RECIPROCATING COMPRESSOR}

The present invention relates to a reciprocating compressor in which a piston sucks and compresses a refrigerant into a compression space while linearly reciprocating in a cylinder, and then discharges the gas. In particular, the circuit part is simplified by reducing the number of inverter switches. The invention relates to a reciprocating compressor.

In general, a compressor is a mechanical device that increases pressure by receiving power from a power generator such as an electric motor or a turbine to compress refrigerant or other various working gases. It is widely used throughout.

These compressors are classified into a reciprocating compressor which compresses the refrigerant while linearly reciprocating the inside of the cylinder by forming a compression space in which the working gas is absorbed and discharged between the piston and the cylinder. And a rotary compressor for compressing the refrigerant while the roller is eccentrically rotated along the inner wall of the cylinder to form a compression space in which the working gas is sucked and discharged between the eccentrically rotating roller and the cylinder. In order to form a compressed space in which the working gas is absorbed and discharged between the orbiting scroll and the fixed scroll, the rotating scroll rotates along the fixed scroll to compress the refrigerant. Divided.

Recently, among the reciprocating compressors, in particular, the piston is directly connected to the reciprocating linear drive motor, there is no mechanical loss due to the movement conversion to improve the compression efficiency as well as a simple reciprocating compressor has been developed a lot.

1 is a view showing a conventional power supply applied to a reciprocating compressor. There is a DC power supply unit 22 for rectifying domestic or industrial AC power (not shown) and converting it into direct current, and a separate controller (not shown) controls the inverter switch unit (S1 to S4) in a pulse width modulation (PWM) method. It controls and supplies AC power (Vm) to the linear motor. The DC power supply unit 22 includes a rectifying unit and a DC link unit rectifying the AC power, but the description and description are omitted since they are general matters. DC power through the rectifying unit (not shown) and the DC link unit (not shown) is changed to the AC power (Vm) having an appropriate size and frequency through the on / off of the inverter switch unit (S1 to S4) by the control unit, This alternating current Vm is applied to the linear motor (exactly the coil of the linear motor).

In this conventional power supply, since four inverter switches must be applied to apply AC power to the linear motor, the on / off control and circuit configuration of the four inverter switches are not only very complicated, The reaction time may be different, so that the desired AC power may not be applied to the linear motor. In addition, there is a problem that the manufacturing cost also increases with the application of a plurality of inverter switches.

Accordingly, an object of the present invention is to provide a reciprocating compressor for supplying a desired AC power supply to a linear motor even if the number of required inverter switches is reduced.

Moreover, an object of this invention is to provide the reciprocating compressor which makes control of an inverter switch part simple, and a circuit structure simple.

It is also an object of the present invention to provide a reciprocating compressor that simplifies the circuit configuration by configuring an AC power supply path to a linear motor with a DC link unit and an inverter switch.

The reciprocating compressor of the present invention is a reciprocating compressor comprising a piston, a cylinder, a coil portion provided in the cylinder to reciprocate the piston, a power supply for supplying power to the coil portion, the power supply is supplied from the AC power supply It consists of a rectifier for rectifying the alternating AC voltage, a DC link part for stabilizing the magnitude of the rectified voltage, and an inverter switch part consisting of a pair of inverter switches connected to the DC link part so that a stable voltage is applied to the coil part. Both ends of the coil part are connected between the DC link part and the pair of inverter switches, respectively, so that the coil part can receive power directly from the DC link part, thereby reducing the number of inverter switches.

In addition, the rectifying portion is preferably composed of a full-bridge diode.

In addition, the DC link unit is composed of a first capacitor and a second capacitor connected in series, both ends of the inverter switch unit is connected to both ends of the DC link unit, it is preferable that the connection point of the first capacitor and the second capacitor is grounded.

In addition, the ground portion of the AC power supply is preferably connected to each other at the connection point of the first capacitor and the second capacitor.

In addition, it is preferable that a pair of inverter switches are alternately turned on and off.

Accordingly, the present invention has an effect that the reciprocating compressor is driven by supplying a desired AC power supply to the linear motor even if the number of necessary inverter switches is reduced.

Further, the present invention has the effect of simplifying the control of the inverter switch unit and simplifying the circuit configuration.

In addition, the present invention has the effect that the maximum power is applied to the linear motor while simplifying the circuit configuration by configuring the AC power supply path to the linear motor by the DC link unit and the inverter switch.

In the following, the invention is explained in detail based on the embodiments of the invention and the accompanying drawings.

2 is a cross-sectional view of a reciprocating compressor to which a power supply device according to the present invention is applied.

In the reciprocating compressor of FIG. 2, an inflow pipe 2a and an outflow pipe 2b through which refrigerant flows in and out of one side of the sealed container 2 are installed, and the cylinder 4 is fixed inside the sealed container 2. In order to compress the refrigerant sucked into the compression space P inside the cylinder 4, the piston 6 is installed in the cylinder 4 so as to reciprocate linear movement and at the same time elastic in the direction of movement of the piston 6. Various springs are installed to be supported, and the piston 6 is installed to be connected to the reciprocating motor 10 generating a linear reciprocating driving force.

In addition, a suction valve 22 is installed at one end of the piston 6 in contact with the compression space P, and a discharge valve assembly 24 is installed at one end of the cylinder 4 in contact with the compression space P. The suction valve 22 and the discharge valve assembly 24 are automatically adjusted to open and close according to the pressure in the compression space P, respectively.

Here, the airtight container 2 is installed so that the upper and lower shells are coupled to each other so that the inside is sealed, and an inlet tube 2a through which refrigerant is introduced and an outlet tube 2b through which the refrigerant is discharged are installed, and a cylinder ( 4) the piston 6 is installed to be elastically supported in the movement direction so as to reciprocate linear movement inside, and the reciprocating motor 10 is assembled to each other by the frame 18 outside the cylinder 4 to constitute an assembly, This assembly is installed to be elastically supported by a support spring 29 on the bottom surface inside the hermetic container 2.

In addition, a predetermined oil is contained in the bottom surface of the airtight container (2), and an oil supply device (30) for pumping oil is installed at the bottom of the assembly, and oil is provided in the lower frame (18) of the assembly. An oil supply pipe 18a is formed to be supplied between the cylinders 4, so that the oil supply device 30 is operated by the vibration generated by the reciprocating linear movement of the piston 6 to pump oil, and The oil is supplied into the gap between the piston 6 and the cylinder 4 along the oil supply pipe 18a to cool and lubricate.

Next, the cylinder 4 is formed in a hollow shape so that the piston 6 can reciprocate linearly, and a compression space P is formed at one side, and one end is located close to the inside of the inflow pipe 2a. It is preferable to be provided on the same straight line as the inflow pipe 2a.

Of course, the cylinder (4) is installed in one end close to the inlet pipe (2a) so that the reciprocating linear movement of the piston 6, the discharge valve assembly 24 is provided at one end on the opposite side to the inlet pipe (2a) Is installed.

At this time, the discharge valve assembly 24 is a discharge cover (24a) is provided to form a predetermined discharge space on one end side of the cylinder 4, and the discharge valve is installed to open and close one end of the compression space (P) side of the cylinder ( 24b) and a valve spring 24c, which is a kind of coil spring that imparts an elastic force in the axial direction between the discharge cover 24a and the discharge valve 24b, and has an O-ring R around one end of the cylinder 4; It is installed so that the discharge valve 24a is in close contact with one end of the cylinder (4).

In addition, between the one side of the discharge cover (24a) and the outlet pipe (2b) is connected to the loop pipe 28 is formed bent, the loop pipe 28 not only guides the compressed refrigerant to be discharged to the outside Vibration caused by the interaction of the cylinder 4, the piston 6, and the reciprocating motor 10 buffers the transmission of the entire sealed container 2.

Therefore, when the pressure of the compression space P becomes equal to or greater than a predetermined discharge pressure as the piston 6 reciprocates linearly inside the cylinder 4, the valve spring 24c is compressed to open the discharge valve 24b. The refrigerant is discharged from the compressed space P, and then completely discharged along the loop pipe 28 and the outlet pipe 2b.

Next, the piston 6 has a refrigerant passage 6a formed at the center so that the refrigerant introduced from the inlet pipe 2a can flow, and one end of the piston 6 adjacent to the inlet pipe 2a is reciprocated by the connecting member 17. In addition to being installed so that the motor 10 is directly connected, the suction valve 22 is installed at one end of the inflow pipe 2a opposite to the inflow pipe 2a, and is installed to be elastically supported by various springs in the movement direction of the piston 6.

At this time, the suction valve 22 is formed in a thin plate shape so that the center portion is partially cut to open and close the refrigerant passage 6a of the piston 6, and one side is fixed by a screw to one end of the piston 6a. It is installed as possible.

Therefore, when the pressure of the compression space P becomes below the predetermined suction pressure lower than the discharge pressure as the piston 6 reciprocates linearly inside the cylinder 4, the suction valve 22 is opened to compress the refrigerant. When the suction in the space P and the pressure in the compression space P becomes equal to or greater than a predetermined suction pressure, the refrigerant in the compression space P is compressed in the state where the suction valve 22 is closed.

In particular, the piston 6 is installed so as to be elastically supported in the movement direction. Specifically, a piston flange 6b protruding in a radial direction at one end of the piston 6 proximate to the inflow pipe 2a includes a mechanical spring such as a coil spring or the like. 8a, 8b is elastically supported in the movement direction of the piston 6, the refrigerant contained in the compression space (P) on the opposite side to the inlet pipe (2a) acts as a gas spring by its elastic force to the piston (6) It will elastically support.

Here, the mechanical springs (8a, 8b) has a constant mechanical spring constant (K _m ) irrespective of the load, the mechanical spring (8a, 8b) is the reciprocating motor (10) relative to the piston flange (6b) It is preferable to be installed side by side in the axial direction, respectively, the predetermined support frame 26 and the cylinder 4 fixed to the machine, the machine is installed on the mechanical spring (8a) and the cylinder (4) supported by the support frame 26 Preferably, the spring 8a is configured to have the same mechanical spring constant K _m .

The drive means 10 comprises a coil part 12, 14 and a magnet 16, and when the power is applied to the coil part to generate a magnetic field, the magnet receives the force, and this force moves the piston 6. It is the driving force.

The reciprocating motor 10 is configured such that a plurality of laminations 12a are stacked in the circumferential direction, and the inner stator 12 is installed to be fixed to the outside of the cylinder 4 by the frame 18, and a coil is wound. A plurality of laminations 14b are circumferentially stacked around the coil winding 14a configured to be formed so as to have a predetermined gap with the inner stator 12 outside the cylinder 4 by the frame 18. Outer stator 14 is installed, and the permanent magnet 16 is located in the gap between the inner stator 12 and the outer stator 14 is installed so as to be connected by the piston 6 and the connecting member (17) However, the coil winding 14a may be installed to be fixed to the outer side of the inner stator 12.

As the current is applied to the coil winding 14a in the reciprocating motor 10 as described above, an electromagnetic force is generated, and the permanent magnet 16 is formed by the interaction between the electromagnetic force and the permanent magnet 16. The reciprocating linear motion, the piston 6 is connected to the permanent magnet 16 is reciprocating linear motion inside the cylinder (4).

3 and 4 are diagrams illustrating the first and second embodiments of the power supply device applied to the reciprocating compressor of the present invention.

The power supply device includes a rectifier 202 for rectifying the AC power supplied from the AC power supply 201, a DC link unit 203 for stabilizing the rectified power, and an inverter switch for controlling the power applied to the coil unit 205. It is comprised by the part 204. AC power is usually supplied from the outside through an AC power supply 201 such as a cable. The rectifier 202 functions to rectify the AC power so as to flow in only one direction, and the DC link unit 203 functions to reduce the variation in the size of the rectified power (stable function). In the rectifying unit 202 and the DC link unit 203, since the purpose is to convert the AC power source into a stable DC power source, the two parts may be bundled together and viewed as a power conversion unit. The inverter switch unit 204 controls the power applied to the inverter through a switch. The controlled power is converted into an AC power source having an appropriate size and frequency via the inverter switch unit 204, and the AC power is applied to the coil unit 205 (corresponding to the coil winding 14a of FIG. 2). .

3 is a view illustrating a first embodiment of a power supply device applied to the reciprocating compressor of the present invention.

The rectifier 202 functions to rectify the AC power and is configured by connecting four diodes in a full-bridge method in FIG. 3. However, since the rectifier is a known technology, the rectifier is rectified so that the AC power flows in only one direction. If it does, it does not affect the effect.

The direct current link unit 203 functions to reduce and stabilize the fluctuating magnitude of the rectified voltage. When the diode is connected and rectified in a full-bridge method as shown in FIG. 3, power is supplied only in one direction, but the magnitude thereof is part of a sine wave, and thus the variation is very high (eg, ripple, etc.). In order to reduce such fluctuations, the DC link unit 203 is provided to stabilize the power supply. Specifically, in Fig. 3, for example, the first capacitor C1 and the second capacitor C2. The first capacitor C1 and the second capacitor C2 are connected in series, and the connection point is grounded separately from the ground of the AC power supply 201.

When the first capacitor C1 and the second capacitor C2 have a large capacitance, the voltages V / 2 between the first capacitor C1 and the second capacitor C2 are highly variable from the rectifier 202. Even when voltage is applied, it is not significantly affected. If the absolute value of the voltages of the first or second capacitors C1 and C2 is smaller than the absolute value of the power supply passing through the rectifier 202, the diode of the rectifier 202 is closed and the voltage of the DC link unit 203 is the inverter. It is caught by the switch unit 204. If the absolute value of the voltage of the first or second capacitors C1 and C2 is greater than the absolute value of the power supply passing through the rectifier 202, the diode of the rectifier 202 is closed and the voltage of the DC link unit 203 is the rectifier ( The voltage passing through the rectifier 202 is applied to the inverter switch unit 204 by being influenced by the power source passed through 202. Through this, it is possible to reduce the magnitude of the voltage fluctuation.

The inverter switch unit 204 includes a first switch (or first inverter switch) S1 and a second switch (or second inverter switch) S2 for power applied to the coil unit 205. Both ends of the inverter switch unit 204 are connected to both ends of the DC link unit 203. That is, one end of the first switch S1 and the second switch S2 is connected to the other capacitors C1 and C2 of the DC link unit 203, and the other end is connected to the coil unit 205. It is. The coil unit 205 is connected between the connection point of the grounded first capacitor C1 and the second capacitor C2 and the connection point of the first switch S1 and the second switch S2.

The power controlled through the first and second switches S1 and S2 is converted into an AC power source having an appropriate size and frequency, and the AC power is applied to the coil unit 205. In FIG. 3, the coil part 205 simply shows the coil part 14a. The control unit (not shown) of the reciprocating compressor alternately turns on / off the first switch S1 and the second switch S2 in controlling the inverter switch unit 204, thereby providing a direct current link to the coil unit 205. The power supply from the unit 203 is applied to sequentially perform the suction stroke, compression stroke, discharge stroke, and re-expansion stroke of the reciprocating compressor. For example, when the first switch S1 is in an on state or an on operation, and the second switch S2 is in an off state or an off operation, + V / 2 is applied to the coil unit 205 to provide a re-expansion stroke. And the suction stroke is sequentially performed, when the first switch S1 is in the off operation or the off state, and the second switch S2 is in the on operation or the on state, -V / 2 is applied to the coil unit 205. Compression and discharge strokes are performed sequentially.

Through this configuration, even if the inverter switches are reduced from four to two, the same function as the conventional one can be achieved. Although the AC power supply unit 201 applies a voltage having a magnitude of V through the rectifying unit 202, when the first or second switches S1 and S2 are in an ON state or an ON operation, the DC link unit 203 Since the voltages applied to the first and second capacitors C1 and C2 are reduced to V / 2, that is, half, the efficiency is reduced. In order to solve this problem, a second embodiment is disclosed.

4 is a diagram illustrating a second embodiment of a power supply device applied to the reciprocating compressor of the present invention.

Since the connection and function of the DC link unit 203 and the inverter switch unit 204 are the same as those of FIG. 3, description thereof is omitted. In the rectifier 202, the second node 102 connected to the AC power source 201 is connected to the ground of the DC link unit 203, that is, the connection point of the first capacitor C1 and the second capacitor C2. . Therefore, the ground portion of the DC link portion 203 and the ground portion of the AC power supply 201 are connected, and the voltage of the second node 102 is always zero. Other than that, the structure of the rectifying part 202 is the same. Accordingly, the voltages at both ends of the first capacitor C1 and the second capacitor C2 of the DC link unit 203 rise to V, and the voltage V is applied to the coil unit 205.

Also in the second embodiment of FIG. 4, the first and second switches S1 and S2 are alternately turned on and off, thereby sequentially performing suction stroke, compression stroke, discharge stroke, and re-expansion stroke of the reciprocating compressor. .

If the voltage of the first node 101 is greater than that of the third node 103, the power flows toward the third node 103 so that the voltage of the third node 103 is equal to the voltage of the AC power source 201. If the voltage of the first node 101 is smaller than that of the fourth node 104, power is supplied from the fourth node 104 so that the voltage of the fourth node 104 is equal to the voltage of the AC power source 201. If the voltage of the first node 101 is between the voltage of the third node 103 and the voltage of the fourth node 104, the diodes are all closed, and if the capacitance of the capacitor constituting the DC link unit 203 is large, The voltage of the DC link portion 203 hardly changes. Through this process, the voltage applied to the inverter switch unit 204 is reduced in magnitude of the voltage through the DC link unit 203. The stabilized DC power is converted into AC power Vm having an appropriate size and frequency through the inverter switch part 204, and AC power Vm is applied to the coil part 205.

In this specification, a control unit for controlling the inverter switch unit 204 according to the PWM signal is not listed, but the configuration of the control unit is only a degree that can be understood by those familiar with the technical field to which the present invention belongs.

In the above, the present invention has been described in detail based on the embodiments of the present invention and the accompanying drawings. However, the scope of the present invention is not limited by the above embodiments and drawings, and the scope of the present invention will be limited only by the contents described in the claims below.

1 is a view showing a conventional power supply applied to a reciprocating compressor.

2 is a cross-sectional view of a reciprocating compressor to which a power supply device according to the present invention is applied.

3 and 4 are diagrams illustrating the first and second embodiments of the power supply device applied to the reciprocating compressor of the present invention.

Claims (5)

In the reciprocating compressor comprising a piston, a cylinder, a coil portion provided in the cylinder to reciprocate the piston, and a power supply device for supplying power to the coil portion, The power supply unit includes a rectifying unit for rectifying the AC voltage supplied from the AC power supply unit, a DC link unit for stabilizing the magnitude of the rectified voltage, and a pair of inverters connected to the DC link unit for applying a stable voltage to the coil unit. Inverter switch unit consisting of switches, Both ends of the coil unit is connected between the DC voltage link unit and a pair of inverter switches, respectively. The method of claim 1, A rectifier comprising a full-bridge diode reciprocating compressor. The method of claim 1, The DC link unit is composed of a first capacitor and a second capacitor connected in series, both ends of the inverter switch unit is connected to both ends of the DC link unit, the connecting point of the first capacitor and the second capacitor is grounded reciprocating compressor . The method of claim 3, A grounded compressor of the AC power supply unit is reciprocating compressor, characterized in that connected to each other at the connection point of the first capacitor and the second capacitor. The reciprocating compressor according to any one of claims 1 to 4, wherein the pair of inverter switches are alternately turned on and off.

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