Variable capacity-type scroll compressor

Details Variable capacity-type scroll compressor Variable capacity-type scroll compressor

1999-08-27

2001-06-12

Thorpe, Timothy S. (Department: 3746)

Pumps

With condition responsive pumped fluid control

Pumped fluid temperature responsive

C417S440000

Reexamination Certificate

active

06244834

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a variable capacity-type scroll compressor effectively applicable to a compressor required to change the discharge capacity thereof in accordance with the driving rotational speed (the rotational speed of the drive shaft).
BACKGROUND ART
A scroll-type compressor described in Japanese Unexamined Patent Publications (Kokai) Nos. 3-33486 and 58-101287 as a variable capacity-type compressor comprises a bypass hole formed at the end plate of a fixed scroll for establishing the communication between the compressor working chamber and the suction side, wherein by opening and closing the bypass hole, the discharge capacity of the compressor is variable. For opening and closing the bypass hole, a solenoid valve or valve means utilizing the differential pressure between the suction pressure and the discharge pressure is used.
The means described above, however, increases the number of parts constituting the variable capacity-type compressor and complicates the structure thereof. The problem is posed, therefore, that the manufacturing cost of the variable capacity-type compressor may be increased and the reliability (durability) thereof may be reduced.
DISCLOSURE OF THE INVENTION
In view of the problem point described above, the object of the present invention is to provide a variable capacity-type scroll compressor in which the discharge capacity can be changed by simple means.
In order to achieve the object described above, the present invention uses the following technical means.
The invention is characterized by a configuration in which a valve body (
23
) for opening or closing a bypass hole (
22
) is forcibly vibrated under a vibratory force generated with the rotation of the shaft (
4
) through an elastic member (
25
).
As a result, the valve body (
23
) is vibrated (displaced) based on the natural frequency &ohgr;
0
determined by the mass of the valve body (
23
) and the elastic constant of the elastic member (
25
). In the case were the vibration frequency of the movable portion such as a movable scroll (
9
), i.e. the number of revolutions per unit time &ohgr; (i.e. the rotational speed) of the shaft
4
is sufficiently small as compared with the natural frequency &ohgr;
0
, therefore, as described later, the valve body (
23
) vibrates with substantially the same phase and amplitude as the movable scroll (
9
). Specifically, in the case where the bypass hole (
22
) is closed with the shaft (
4
) kept stationary, the closed state is maintained, while if the bypass hole (
22
) is opened in that state, the open state is maintained.
In the case where the rotational speed of the shaft (
4
) and the orbital vibration frequency &ohgr; of the movable scroll (
9
) have become sufficiently large as compared with the natural frequency &ohgr;
0
, the valve body (
23
) is vibrated (displaced) relative to the movable scroll (
9
) and the bypass hole (
22
). The bypass hole (
22
) thus is opened and closed by the valve body (
23
). The valve body (
23
) can open or close the bypass hole (
22
), therefore, by selecting an appropriate natural frequency &ohgr;
0
.
As described above, according to this invention, the bypass hole (
22
) can be opened and closed by simple means in which the natural frequency &ohgr;
0
of the vibration system including the valve body (
23
) and the elastic member (
25
) is set to a predetermined value and the valve body (
23
) is forcibly vibrated by the shaft (
4
) through the elastic member (
25
). By doing so, the discharge capacity of the compressor can be changed. Thus, the manufacturing cost of the compressor can be reduced and the reliability (durability) thereof can be improved.
The invention in an aspect is characterized in that the elastic constant of the elastic member is changed in accordance with the fluid temperature on the fluid suction side.
As a result, the open/close timing of the bypass hole (
22
) can be controlled based on the fluid temperature on the fluid suction side. As described later, therefore, in the case where the variable capacity-type compressor according to this invention is applied to the refrigeration cycle, the open/close timing of the bypass hole (
22
) can be controlled in accordance with the thermal load on the evaporator.
By the way, the elastic member can be configured as a fluid spring by introducing the fluid of the fluid suction side.
Also, the elastic member may be formed of a shape memory alloy the shape of which is changed in accordance with the atmospheric temperature. By the way, in this case, the elastic member of a shape memory alloy is desirably exposed directly to the fluid on the fluid suction side.
Also, a plurality of valve bodies (
23
a
,
23
b
) and elastic members (
25
a
,
25
b
) may be provided and the natural frequency determined by the elastic constant of the valve bodies (
23
a
,
23
b
) and the elastic members (
25
a
,
25
b
) may be set to different values. By doing so, the open/close operation of the bypass hole can be controlled in multiple stages.
Also, the value body (
23
) may be configured in such a manner as to receive the vibratory force from the end plate portion (
9
b
) of the movable scroll (
9
). Also, the valve body (
23
) may be configured so as to close the bypass hole (
22
) while the shaft (
4
) is stationary.
By the way, the reference numerals in the parentheses for each means described above illustrate the correspondence with the specific means according to the embodiments described later.


REFERENCES:
patent: 5040952 (1991-08-01), Inoue et al.
patent: 5362211 (1994-11-01), Iizuka et al.
patent: 5639255 (1997-06-01), Matsuda et al.
patent: 5759021 (1998-06-01), Yamaguchi et al.
patent: 5860791 (1999-01-01), Kikuchi
patent: 58-101287 (1983-06-01), None
patent: 62-67288 (1987-03-01), None
patent: 3-33486 (1991-02-01), None

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