JPH03237285A - Capacity control device for scroll compressor - Google Patents

Abstract

PURPOSE:To reduce the number of parts and the manday of machining and assembling so as to reduce the cost in large degree by providing a cylinder with one end thereof communicated with a suction chamber across by-pass holes for allowing the by-passing of gas in compression chambers, and providing a piston in the cylinder with passages for opening the by-pass holes into the suction chamber. CONSTITUTION:By-pass holes 33a, 33b for allowing the by-passing of gas during the compression stroke in compression chambers 19a, 19b are bored at the end plate 11 of a fixed scroll 10, and a cylinder 50 with one end thereof communicated with a suction chamber 28 is bored across these by-pass holes 33a, 33b. A piston 51 is provided with through holes 61a, 61b bored to communicate the by-pass holes 33a, 33b simultaneously with a blind hole 52, a through hole 62 bored to communicate a by-pass hole 60 with the blind hole 52, and a slotted hole 63 bored to pass a discharge pipe 58 through. At the time of reducing the capacity of a compressor, control pressure acts upon the other end face of the piston 51 through a through hole 57 and a chamber 56, and the piston 51 advances into a position where the pressing force of control pressure and the spring force of a coil spring run parallel to each other so as to discharge gas during the compression stroke in the compression chambers 19a, 19b into a suction chamber 28.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a capacity control device for a scroll compressor suitable for use in vehicle air conditioners and the like.

(Conventional technology) An example of a conventional device is shown in FIGS. 4-6.

In FIG. 4, reference numeral 1 denotes a closed housing, which is composed of a cup-shaped main body 2, a front end plate 4 fastened to this by bolts 3, and a cylindrical member 6 fastened to this by bolts 5. A main shaft 7 passing through the cylindrical member 6 is rotatably supported by bearings 8 and 9.

A fixed scroll 1o is disposed within the hermetic housing 1, and the fixed scroll 1O includes an end plate 11 and a spiral wrap I2 erected on its inner surface. 2 has been concluded.

The orbiting scroll 14 includes an end plate 15 and a spiral wrap 16 erected on its inner surface, and the spiral wrap 16 has substantially the same shape as the spiral rubber 12 of the fixed scroll 10. .

The orbiting scroll 14 and the fixed scroll 10 are eccentric to each other by the revolution radius and are meshed with each other at an angle of 180'' as shown in the figure, and the spiral wrap 12
The tip seal 17 embedded in the tip surface of the spiral wrap 6 is in close contact with the inner surface of the end plate 15, and the tip seal 18 embedded in the tip surface of the spiral wrap 6 is in close contact with the inner surface of the end plate 11. The sides of 12 and 16 are located at point a, as shown in FIG.
, b, c, and d, and thus a plurality of compression chambers 19a and 19b are formed which are approximately point symmetrical with respect to the center of the spiral.

A cylindrical boss 20 protruding from the center of the outer surface of the end plate 15 has a tribe bushing 2 inside it. is rotatably fitted through a bearing 23, and an eccentric pin 25 protruding from the inner end of the main shaft 7 is rotatably fitted into an eccentric hole 24 formed in the drive bush 21. has been done.

Further, a rotation prevention mechanism 26 that also serves as a thrust bearing is arranged between the outer peripheral edge of the outer surface of the end plate 15 and the inner surface of the front end plate 4.

When the main shaft 7 is rotated, the orbiting scroll 14 is driven via the eccentric pin 25, the drive bush 21, and the boss 20.
The revolution radius while being prevented from rotating by 6, that is,
It revolves around a circular orbit whose radius is the amount of eccentricity between the main shaft 7 and the eccentric pin 25. Then, the spiral wraps 12 and 1
The line contact portions a to d with 6 gradually move toward the center of the spiral, and as a result, the compression chambers 19a and 19b move toward the center of the spiral while decreasing their volumes.

Along with this, gas flowing into the suction chamber 28 through the suction port (not shown) is taken into each compression chamber 19a, 19b from the outer end opening of the spiral wraps 12 and 16, and is compressed into the center. Finally, fixed scroll 1 from here
The discharge valve 30 is pushed open through the discharge port 29 drilled in the end plate 11 of 0, and the discharge is discharged into the cavity 31 bounded by the end plate 11 and the housing l, from which it flows out through a discharge port (not shown). .

Inside the end plate 11 of the fixed scroll 10, there are
As shown in the figure, a pair of cylinders 32a and 32b are bored, one end of which communicates with the suction chamber 28, and these pair of cylinders 32a and 32b are located on both sides of the discharge port 29 and spaced apart from each other by a predetermined distance. extending in parallel. In addition, bypass holes 33a and 33B are bored in the end plate 11 for bypassing the gas that is being compressed from the pair of compression chambers 19a and 19b to the cylinders 32a and 32b. And these cylinders 32a, 32
Pistons 34a and 34b for opening and closing the bypass holes 33a and 33b are fitted into the pistons b in a sealed and slidable manner.

However, when the compressor is operating at full load, the piston 3
High-pressure control gas generated by the control valve 38 is introduced into the inner end surfaces of the pistons 4a and 34b through the through holes 39a and 39b, and the pistons 34a and 34b are connected to the spring receivers 4 and 4a.
The bypass holes 33a and 33b are closed by moving the return springs 41a and 41b forward against the elastic force of the return springs 41a and 41b interposed in a compressed state between the return springs 0a and 40b.

On the other hand, is the capacity system of pressure? During il operation, the piston 34
The pressure of the control gas introduced into each inner end of a, 34b is reduced. Then, each piston 34a, 34b retreats by the elastic force of the return springs 41a, 41b and occupies the position shown in the figure, and the gas that is being compressed from the pair of compression chambers 19a, 19b passes through the bypass holes 33a, 33b.
Holes 42a and 4 bored in the pistons 34a and 34b
2b, cylinders 32a, 32b and flows into the suction chamber 28. In addition, 27 is a balance weight attached to the inner end of the main shaft 7, 35 is a retainer of the discharge valve 30, and 36
are bolts that fasten the discharge valve 30 and the retainer 35 to the end plate 11.

(Issues to be Solved by the Invention) In the above-mentioned conventional compressor, in order to bypass the gas in the middle of compression from a pair of compression chambers 19a and 19b, which are formed point-symmetrically with respect to the center of the spiral. , end plate l
A pair of cylinders 32a, 32b are formed in the cylinder 1, and pistons 34a, 34b and return springs 41a, 41b are installed in the cylinders 32a, 32b, respectively.
, it is necessary to provide two sets of spring receivers 40a, 40b, etc.

As a result, the structure becomes complicated, resulting in an increase in the number of parts and the number of assembly and processing steps, as well as an increase in cost and weight.

(Means for Solving the Problems) The present invention was invented to solve the above problems, and the gist of the first invention is that a spiral wrap is formed on the inner surface of each end plate. By meshing the fixed scroll and the orbiting scroll, a pair of compression chambers are formed point-symmetrically with respect to the center of the spiral wrap. The gas sucked into the compression chamber is compressed as the compression chamber moves toward the center of the spiral wrap while decreasing its volume, and the compressed gas is formed on the end plate of the fixed scroll. In a scroll type compressor that discharges from a discharge port, the end plate of the fixed scroll has at least a pair of bypass holes for bypassing gas that is being compressed in the pair of compression chambers, and the scroll compressor straddles the pair of bypass holes, and , a passageway comprising a cylinder whose one end communicates with the suction chamber, and through which a piston slidably fitted into the cylinder opens the pair of bypass holes to the suction chamber at a predetermined sliding position; There is provided a capacity control device for a scroll compressor, characterized in that:

The gist of the second invention is characterized in that a discharge pipe for connecting the discharge port is provided across the cylinder, and the piston is provided with an elongated hole extending in the sliding direction of the piston through which the discharge pipe passes. Claim (1)
) in the capacity control device for a scroll compressor.

The gist of the third invention is to provide point symmetry with respect to the center of the spiral wrap by meshing a fixed scroll and an orbiting scroll each having a spiral wrap erected on the inner surface of an end plate. A pair of compression chambers are formed in the orbiting scroll, and by rotating the orbiting scroll, the compression chamber moves the gas sucked into the compression chamber from the suction chamber toward the center of the spiral wrap while reducing its volume. In a scroll type compressor that compresses the gas according to the fixed scroll and discharges the compressed gas from a discharge port formed in the end plate of the fixed scroll to a discharge cavity formed by the end plate of the fixed scroll and the housing, at least a pair of bypass holes in the end plate for bypassing gas that is being compressed in the pair of compression chambers;
A cylinder that straddles these pair of bypass holes and has one end communicating with the suction chamber, and a bypass passage that has one end communicating with the outlet side of the discharge port and the other end opening into the cylinder, and the cylinder Claim (1) characterized in that a passage is formed that sequentially opens the pair of bypass holes and the bypass passage to the suction chamber during the sliding process of one piston that is slidably fitted therein. ) in the capacity control device for a scroll compressor.

(Function) In the first invention, when controlling the capacity of the compressor, by moving one piston to a predetermined sliding position, the gas that is being compressed from the pair of compression chambers passes through the pair of bypass holes and into the cylinder. enters and is bypassed to the suction chamber.

In the second invention, rotation of the piston around the axis is prevented by the discharge pipe.

In the third invention, when controlling the capacity of the compressor, the pair of bypass holes and the bypass passage are sequentially opened to the suction chamber in the course of sliding of the - pistons.

Embodiment One embodiment of the invention is shown in FIGS. 1-3.

A pair of compression chambers 19a are provided in the end plate 11 of the fixed scroll 10.
A pair of bypass holes 33a and 33b for bypassing the gas that is being compressed in 519b is bored, and the bypass hole straddles the pair of bypass holes 33a and 33b,
Also, one cylinder 50 is bored, one end of which communicates with the suction chamber 28. A piston 51 is fitted into the cylinder 5° so as to be slidable in a sealed manner. This piston 51 has a blind hole 5 extending from one end to almost its entire length.
2 is bored, and a coil spring 55 is in a compressed state between a shoulder portion 53 formed approximately in the middle of this blind hole 52 and a spring receiver 54 that also serves as a stopper fixed to the end of the suction chamber 28 side of the cylinder 5o. It is interposed with. A control valve 38 is connected to a chamber 56 bounded by the cylinder 50 and the other end of the piston 51 fitted therein through a through hole 57.
The control pressure generated in

A discharge pipe 58 that also serves as a discharge port 29 is connected to the cylinder 50.
One end of a groove 59 bored on the outer surface of the end plate 11 communicates with the outlet end of the discharge pipe 58, and the other end of this groove 59 communicates with the bypass hole Go. ing. This groove 59 is covered by the discharge valve 3o.

The piston 51 has bypass holes 33a and 33b.
through holes 61a and 61b that simultaneously communicate with the blind hole 52, and a through hole 62 that communicates the bypass hole 60 with the blind hole 52,
A long hole 63 is bored in the sliding direction of the piston 51 for passing the discharge pipe 58 therethrough.

Note that the bypass holes 33a and 33b are connected to the compression chambers 19a and 19.
While b progresses from the rotation angle of the orbiting scroll 14 at which its maximum volume reaches a predetermined rotation angle, that is, the compression chamber 19a
, 19b finishes inhaling the gas and enters the compression stroke to reduce its volume to, for example, 50% of the compression chamber 1.
9a and 19b.

The rest of the structure is the same as the conventional one shown in FIGS. 4 to 6, and corresponding members are given the same reference numerals.

During unload operation of the compressor, the control pressure generated by the control valve 38 decreases, so the piston 51 is pushed by the restoring force of the coil spring 55 and occupies the illustrated position, and the bypass holes 33a and 33b are closed. The bypass hole 60 communicates with the blind hole 52 through the through holes 61a and 61b, and the bypass hole 60 communicates with the blind hole 52 through the through hole 62. Therefore, the gas that is being compressed in the compression chambers 19a, 19b enters the blind hole 52 via the bypass holes 33a, 33b and the through holes 61a, 61b, and the gas in the compression chambers that has come to the center of the spiral, that is, The remaining gas passes through the discharge pipe 58, the concave groove 59, the bypass hole 60. Blind hole 52 via through hole 62
They join together and are discharged through the cylinder 50 into the suction chamber 28, so that the capacity of the compressor becomes zero.

When the compressor is operating at full load, control valve 3
8 generates high control pressure. Then, this high control pressure enters the chamber 56 through the through hole 57, and the piston 51
Press the other end surface. Thus, the piston 51 moves forward against the elastic force of the coil spring 55 and stops at a position where one end thereof abuts the spring receiver 54 which also serves as a stopper.

In this state, the bypass holes 33a, 33b and the bypass hole 60 are all closed by the piston 51, so the gas compressed in the compression chambers 19a, 19b and coming to the compression chamber in the center of the spiral passes through the discharge pipe 58. Discharge valve 3
0 is pushed open and discharged into the discharge cavity 31, and then discharged to the outside through a discharge port (not shown).

When reducing the capacity of the compressor, a control pressure corresponding to the reduction rate is generated at the control valve 38. When this control pressure acts on the other end surface of the piston 51 through the through hole 57 and the chamber 56, the piston 5I advances to a position where this pressing force and the elastic force of the coil spring 55 are balanced. Then, the through holes 61a and 61b become the bypass holes 33a and 33.
b, and the gas being compressed in the compression chambers 19a, 19b passes through the bypass holes 33a, 33b, and the il hole 61a.
, 61b , the suction chamber 2 via the blind hole 52 and the cylinder 50
8 and the compressor capacity is reduced to 50%. When the piston 51 is further advanced to communicate the bypass hole 60 with the through hole 62, the capacity of the compressor becomes zero.

When the piston 51 slides within the cylinder 50, the discharge pipe 58 moves within the through hole 63 while being guided therethrough, so that rotation of the piston 51 around the axis is prevented by the discharge pipe 58.

In addition, in the above embodiment, the pair of bypass holes 33a
, 33b, but two or more pairs of bypass holes may also be provided.

(Effects of the Invention) In the first invention, the end plate of the fixed scroll has at least one pair of bypass holes for bypassing gas that is being compressed in a pair of compression chambers, and straddles the pair of bypass holes, and A cylinder is provided with one end communicating with the suction chamber, and a passage is formed in which a piston is slidably inserted into the cylinder housing and opens the pair of bypass holes to the suction chamber at a predetermined sliding position. Therefore, there is no need for two sets of cylinders, pistons, etc. as in the conventional case.

Therefore, the structure is simplified, and the number of parts and the number of processing and assembly steps are reduced, so that costs can be significantly reduced.

Further, since the pair of bypass holes are opened and closed simultaneously by one piston, there is no difference in the timing of opening and closing of the pair of bypass holes unlike in the conventional system, and therefore, control safety is improved.

In the second invention, the discharge pipe constituting the discharge port is provided across the cylinder wood, and the piston is provided with a long elongated hole in the sliding direction of the piston through which the discharge pipe passes. Rotation is prevented, so the bypass hole can be reliably opened and closed.

In the third invention, the end plate of the fixed scroll has at least a pair of bypass holes for bypassing gas that is being compressed in a pair of compression chambers, and a bypass hole that straddles the pair of bypass holes and has an end located in the suction chamber. A process in which a piston, which is slidably inserted into the cylinder hole, is provided with a bypass passage whose one end communicates with the outlet side of the discharge port and whose other end opens into the cylinder. By forming a passage in which a pair of bypass holes and a bypass passage are sequentially opened to the suction chamber, the reduction rate of the compressor capacity can be selected depending on the sliding position of the piston, and by opening the bypass passage to the suction port. , it becomes possible to unload the compressor.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a partial longitudinal cross-sectional view of the main part, FIG. 2 is a cross-sectional view taken along the -■ arrow in FIG. 1, and FIG. 1 is a partially enlarged cross-sectional view taken along the arrow ■-■ in FIG. 1. FIG. 4 to 6 show an example of a conventional device, in which FIG. 4 is a longitudinal sectional view, FIG. 5 is a partial sectional view taken along the line V-V in FIG. 6, and FIG. FIG. 2 is a cross-sectional view along the line Vl-Vl of FIG. Fixed scroll -1O1 end plate -41, spiral wrap -12, orbiting scroll -14, end plate -15,
Spiral wrap--I6, compression chamber--19a,
19b, bypass hole -33a, 33b, cylinder -50, piston -51, suction chamber -28, passage -61a, 61b, 52, discharge pipe -5
8, Elongated hole -63, Discharge cavity -31, Housing...1, Figure 6

Claims (3)

[Claims] (1) A pair of compression chambers are formed symmetrically with respect to the center of the spiral wrap by meshing a fixed scroll and an orbiting scroll each having a spiral wrap erected on the inner surface of an end plate. , by causing the orbiting scroll to revolve around the orbit, the gas sucked into the compression chamber from the suction chamber is compressed as the compression chamber moves toward the center of the spiral wrap while decreasing its volume. In a scroll type compressor that discharges compressed gas from a discharge port formed in an end plate of the fixed scroll, the end plate of the fixed scroll is provided with at least a pair of gases for bypassing gas that is being compressed in the pair of compression chambers. A bypass hole and a cylinder that spans the pair of bypass holes and has one end communicating with the suction chamber are provided, and a piston that is slidably inserted into the cylinder is positioned at a predetermined sliding position. A capacity control device for a scroll compressor, characterized in that a passage is formed to open the pair of bypass holes to the suction chamber. (2) Claim (1) characterized in that a discharge pipe constituting the discharge port is provided across the cylinder, and the piston is provided with an elongated hole extending in the sliding direction of the piston through which the discharge pipe passes. A capacity control device for the scroll compressor described above. (3) A pair of compression chambers are formed point-symmetrically with respect to the center of the spiral wrap by meshing a fixed scroll and an orbiting scroll each having a spiral wrap erected on the inner surface of the end plate. By rotating the orbiting scroll, the gas sucked into the compression chamber from the suction chamber is compressed as the compression chamber moves toward the center of the spiral wrap while reducing its volume. In a scroll compressor that discharges gas from a discharge port formed in an end plate of the fixed scroll to a discharge cavity formed by an end plate of the fixed scroll and a housing, the pair of at least a pair of bypass holes for bypassing gas that is being compressed in the compression chamber; a cylinder that straddles the pair of bypass holes and has one end communicating with the suction chamber; and one end facing the outlet side of the discharge port. A bypass passage is provided that communicates with the cylinder, and the other end opens into the cylinder, and the pair of bypass holes and the bypass passage are sequentially connected in the process of sliding of a piston that is slidably inserted into the cylinder. 2. A capacity control device for a scroll compressor according to claim 1, further comprising a passageway opening into said suction chamber.