JP2931184B2 - 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 linear compressor for compressing an explosive gas.

[0002]

2. Description of the Related Art Conventionally, a linear compressor has been known. This linear compressor has a cylinder in which at least one end has a cylinder bore serving as a compression chamber for explosive gas compression, a piston slidably fitted in the cylinder bore, and controls gas suction and gas discharge into the compression chamber. And a linear motor mechanism for reciprocating the piston.The linear motor mechanism is composed of a permanent magnet fitted to the outer periphery of the piston, and a soft magnet fixedly functioning as a cylinder or fixed to the cylinder. A stator core consisting of a body,
A stator coil wound around the stator core to form an alternating magnetic field for reciprocating the permanent magnet in the axial direction.

A type in which a compression chamber is formed on one side of a cylinder bore is called a single-head type, and a type in which a compression chamber is formed on both sides of a cylinder bore is called a double-head type. The double-headed type is advantageous for miniaturization and large output for various reasons. Various linear motor principles can be adopted as the linear motor mechanism.
The simplest method is to fit a piston having a permanent magnet or a soft magnetic material into the cylinder bore between the air gaps of the stator core, and to arrange this permanent magnet or soft magnetic material between the air gaps of the stator core. It is. When an alternating current or an intermittent current is applied to the stator coil wound around the stator core, both ends of the stator core sandwiching the air gap are excited to opposite magnetic poles, thereby causing the permanent magnet or the soft magnetic material on the piston side to rotate. Be energized. For example, in the case of a permanent magnet, it moves forward by magnetic attraction and moves backward by magnetic repulsion. Further, in the case of a soft magnetic material, it moves forward in the air gap disappearing direction due to the magnetic attraction force and moves backward by the spring.

In addition, a linear motor mechanism using various motor driving principles can be adopted. A conventional example of a double-headed piston type linear compressor is disclosed in
No. 4950 discloses a configuration in which a stator core, a stator coil, and a rotor core (yoke) with a permanent magnet are hermetically sealed in a housing.

[0005]

In the above-mentioned conventional linear compressor, for example, as disclosed in the above publication, the stator coil is hermetically housed in a housing. However, when compressing an explosive gas such as hydrogen gas, it is inevitable that hydrogen gas leaks from the piston ring to a space on the side of the linear motor mechanism (hereinafter referred to as a driving chamber).

As a result, if a crack or the like occurs in the resin layer or the resin bobbin that covers the stator coil and a discharge occurs between the windings of the stator coil due to poor coil insulation or the like, the gas may explode. . The present invention has been made in view of the above problems, and has as its object to provide a linear compressor with improved safety against leaked explosive gas.

[0007]

SUMMARY OF THE INVENTION A linear compressor according to the present invention comprises a cylinder having at least one end provided with a cylinder bore serving as a compression chamber for compressing explosive gas, and a piston slidably fitted into the cylinder bore. A suction valve and a discharge valve for controlling gas suction and gas discharge to and from the compression chamber, and a linear motor mechanism for reciprocating the piston, wherein the linear motor mechanism is fitted to an outer peripheral portion of the piston. A permanent magnet or a soft magnetic material, a stator core which also serves as the cylinder or is made of a soft magnetic material fixed to the cylinder, and an alternation wound around the stator core to reciprocate the permanent magnet in the axial direction. And a stator coil for forming a magnetic field, wherein an outer peripheral surface of the stator coil is formed through a communication hole formed in the stator core. It is characterized by being open to.

[0008]

The outer peripheral surface of the stator coil of the linear motor mechanism is open to the outside through a communication hole formed in the stator core. Therefore, for example, even if a crack occurs in a resin bobbin around which the stator coil is wound and an explosive gas enters the portion of the stator coil, the explosive gas is quickly diffused from the outer peripheral surface of the stator coil to the outside air, and As a result, the explosive gas does not stay inside the stator coil and the concentration does not increase beyond the explosive limit concentration, so that the explosion can be prevented.

[0009]

The present invention will be specifically described below with reference to examples. (Embodiment 1) An embodiment of a linear compressor according to the present invention will be described with reference to FIG. This linear compressor is
A yoke (yoke) 1 made of a soft iron cylinder having both ends opened is provided. A valve portion 2, a magnetic pole core 3, a resin bobbin 4, a magnetic pole core 3, a valve portion are provided in a through hole in the yoke 1 in order from one end. 2 are sequentially fitted, and the cylinder heads 5 are individually screwed into both ends of the through hole of the yoke 1.

A stator coil 6 is wound around the resin bobbin 4, and the resin bobbin 4 has flanges 41 at both ends. The outer periphery of the flange 41 is in contact with the inner peripheral surface of the yoke 1. An AC voltage is applied to the stator coil 6 from an AC power supply 60. 61 is a capacitor for canceling the reactive current component of the stator coil 6. The magnetic pole core 3 is made of a soft iron cylinder having both ends opened, and constitutes a cylinder referred to in the present invention. The outer diameter of both pole cores 3 is equal to the outer diameter of flange 41 of resin bobbin 4, the inner diameter of both pole cores 3 is equal to the inner diameter of resin bobbin 4, and the holes of both pole cores 3 communicate with each other. To form a cylinder bore.

A double-headed piston 7 made of an aluminum alloy is slidably fitted in the holes of the resin bobbin 4 and the two pole cores 3.
A piston ring 70 is fitted in sliding contact with the inner peripheral surface of the piston ring 70. The double-headed piston 7 is formed by screwing a left half 71 in which a cylindrical permanent magnet 8 is fitted to a small-diameter right end and a right half 72, and both end faces of the double-headed piston 7 will be described later. Bolt 2
9 is formed with a cylindrical concave portion 73 for avoiding interference with the head. In FIG. 1, the left end of the permanent magnet 8 is magnetized to the N pole, and the right end is magnetized to the S pole in FIG.

The valve portion 2 includes a valve plate 21 made of a short-axis cylinder made of a non-magnetic metal such as stainless steel,
A suction valve V1 and a discharge valve V2 are individually adhered to both end surfaces of the valve plate 21. Reeds (not shown) are formed in the suction valve V1 on the piston side and the discharge valve V2 on the cylinder head side, respectively. I have. The suction valve V1 and the discharge valve V2 are fixed to the valve plate 21 by bolts 29 and nuts 28 penetrating into the center of the valve plate 21. In the valve plate 21,
A suction hole 22 that can be opened and closed by a lead of the suction valve is provided in the axial direction, and a discharge hole 23 is provided in the axial direction so as to be opened and closed by a lead of the discharge valve.

The cylinder head 5 is formed of a short-axis cylinder made of an aluminum alloy, and a suction chamber 52 communicating with the suction hole 22 and a discharge chamber 53 communicating with the discharge hole 23 are formed on the inner end surface thereof. I have. Reference numeral 54 denotes a suction pipe for introducing hydrogen gas from the outside into the suction chamber 52, and reference numeral 55 denotes a discharge pipe for discharging hydrogen gas from the discharge chamber 53 to the outside.
Is connected to the outer end face of the

As a result, the double-headed piston 7 defines a compression chamber at both ends of the cylinder bore. Yoke 1, magnetic pole core 3, resin bobbin 4, stator coil 6 described later, permanent magnet 8
Constitutes a linear motor mechanism according to the present invention. The yoke 1 and the magnetic pole core 3 constitute a stator core according to the present invention. The present embodiment is characterized in that the communication hole 18 is provided in the yoke 1 in the linear compressor described above.

The communication hole 18 exposes the outer peripheral surface of the stator coil 6 to the external space. The communication hole 18 is located at the center of the yoke 1 in the axial direction, and is opened in the circumferential direction at a plurality of intervals. ing. Hereinafter, the operation of the linear compressor will be described. When an AC current having a predetermined frequency is applied to the stator coil 6 from the AC power supply 60, the left and right magnetic pole cores 3 and 3 are alternately magnetized into N poles and S poles. When the left magnetic pole core 3 is magnetized to the S pole, the permanent magnet 8 whose left end portion is magnetized to the N pole is attracted to the left direction, and when the left magnetic pole core 3 is magnetized to the N pole. , And is biased rightward, whereby the double-headed piston 7 reciprocates.

Then, when the volume of the compression chamber increases, the hydrogen gas pushes open the tongue constituting the suction valve body and flows into the compression chamber, and when the volume of the compression chamber decreases, the pressurized hydrogen gas in the compression chamber passes through the discharge valve body. The above-described tongue part is pushed open to be discharged. In the following, the operation of this embodiment will be described. First, the case where there is no communication hole 18 will be considered.

In this case, the hydrogen gas pressurized in the compression chamber leaks over the piston ring 70 to the inner peripheral surface side of the resin bobbin 4. Here, if a crack occurs in the cylindrical body of the resin bobbin 4, hydrogen gas flows into the stator coil 6 from the crack. As a result, if air (oxygen gas) remains inside or around the stator coil 6,
There is a risk that hydrogen gas will reach explosive concentration. Similarly, hydrogen gas inevitably leaks from the gap between the outer periphery of the flange 41 of the resin bobbin 4 and the inner periphery of the yoke 1 to the outer periphery of the stator coil 6, and the outer periphery of the stator coil 6 A similar danger arises in the vicinity.

On the other hand, when the communication hole 18 is provided,
Even if hydrogen gas enters the inside or the inner peripheral surface of the stator coil 6, the hydrogen gas passes through a minute gap inside the stator coil 6 or a gap between the stator coil 6 and the resin bobbin 4. And rapidly diffuses outside through the communication hole 18. The same applies even if hydrogen gas enters the vicinity of the outer peripheral surface of the stator coil 6.

As a result, even if hydrogen gas leaks around the stator coil 6, the hydrogen gas does not have an explosive concentration, and the explosion of the hydrogen gas due to, for example, generation of spark discharge can be avoided. Therefore, the shape and size of the communication holes 18 are free as long as hydrogen gas leakage is possible, and the number of the communication holes 18 is also free. However, considering that there is much leakage from the gap between the outer peripheral surface of the flange portion 41 of the resin bobbin 4 and the inner peripheral surface of the yoke 1, it is preferable that the opening be provided close to the flange portion 41. (Embodiment 2) A linear compressor according to another embodiment will be described with reference to FIG.

In this embodiment, the structures of the valve section 2 and the cylinder head 5 are the same as those of the first embodiment, and are not shown.
In this embodiment, a single magnetic pole core 3 is inserted in the axial center of the yoke 1, and a cylinder portion 9 made of an aluminum alloy cylinder is inserted between the magnetic pole core 3 and both valve portions 2. Have been.

Slots 39 formed of annular grooves are formed in the inner peripheral surface of the magnetic pole core 3 at equal intervals in the axial direction, and the slots 39 accommodate the stator coils 6 of the respective phases. In addition, the stator coil 6 is provided with a slot 39 on the left end side.
, A U-phase coil, a V-phase coil, and a W-phase coil in this order from the slot 39 on the right side. Accordingly, the teeth between the slots 39 are magnetic poles in this embodiment.

The permanent magnet 8 fitted to the center of the piston 7 has N pitches equal to the axial pitch of the magnetic poles.
The pole and the south pole are magnetized. The operation of this linear motor mechanism will be described. This drive mechanism has the same principle as that of a so-called three-phase synchronous motor.
By applying a three-phase AC voltage to the V-phase coil and the W-phase coil, the piston 7 is driven to reciprocate. It is a well-known matter that a sensor for detecting the position of the piston 7 is provided, and the voltage of the U-phase coil, the V-phase coil, and the W-phase coil of the stator coil 6 is switched by the output of the sensor. Also, a soft iron cylinder is inserted into the piston 7 in place of the permanent magnet 8, and slots formed of circumferential grooves are formed in the soft iron cylinder at equal intervals in the axial direction, and conductor rings are embedded in these slots, so-called, Of course, it is also possible to employ an induction motor type linear motor mechanism.

In this embodiment, the outer peripheral surface of the stator coil 6 is communicated with the outside air by the communicating hole 18 opened in the yoke 1 and the communicating hole 38 communicating the communicating hole 18 with the outer periphery of the slot 39. Thus, the same effect as in the first embodiment can be obtained. (Modification) FIG. 3 shows an embodiment in which a DC power supply E is used instead of the AC power supply 60 of the first embodiment.

An AC voltage is applied to the stator coil 6 by switching a single-phase inverter circuit composed of MOS power switches 101 to 104 on and off. FIG. 4 shows an embodiment in which a DC power supply E is used to drive the linear motor mechanism according to the second embodiment. Each of the three-phase AC voltages is individually applied to the U-phase coil, the V-phase coil, and the W-phase coil of the stator coil 6 by the intermittent operation of a three-phase inverter circuit including MOS power switches 201 to 206.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a linear compressor of the present invention.

FIG. 2 is a sectional view showing another embodiment of the linear compressor of the present invention.

FIG. 3 is a circuit diagram showing a modification of the AC power supply of FIG. 1;

FIG. 4 is a circuit diagram showing the AC power supply of FIG. 2;

[Explanation of symbols]

1 is a yoke, 2 is a valve part, 3 is a magnetic pole core, 4 is a resin bobbin, 5 is a cylinder head, 6 is a stator coil, 7 is a piston, 8 is a permanent magnet, and 18 is a communication hole.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hirohisa Kato 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Nobuo Fujita 1-Toyota-cho, Toyota-shi, Aichi Prefecture Toyota Motor Vehicle Stock within the company (72) inventor Hiroyuki Mitsui Aichi Prefecture Aichi-gun Nagakute Oaza Nagakute-shaped side street 1 Co., Ltd. Toyota central research Institute in the address of 41 (58) investigated the field (Int.Cl. ^6, DB name) F04B 35/04

Claims (1)

(57) [Claims] 1. A cylinder having a cylinder bore at least one end of which serves as a compression chamber for compressing an explosive gas, a piston slidably fitted into the cylinder bore, and gas suction and gas discharge into the compression chamber. And a linear motor mechanism for reciprocating the piston, wherein the linear motor mechanism includes a permanent magnet or a soft magnetic material fitted to an outer peripheral portion of the piston, and the cylinder. A linear comprising a stator core which is also made of a soft magnetic material and is fixed to the cylinder, and a stator coil which is wound around the stator core and forms an alternating magnetic field for reciprocating the permanent magnet in the axial direction. In the compressor, an outer peripheral surface of the stator coil is open to the outside air through a communication hole formed in the stator core. Lessa.