U.S. patent application number 11/862344 was filed with the patent office on 2008-04-03 for reciprocating compressor.
This patent application is currently assigned to ANEST IWATA CORPORATION. Invention is credited to Hiroshi INOUE.
Application Number | 20080080995 11/862344 |
Document ID | / |
Family ID | 39255418 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080080995 |
Kind Code |
A1 |
INOUE; Hiroshi |
April 3, 2008 |
RECIPROCATING COMPRESSOR
Abstract
A reciprocating compressor includes a suction port, through
which a working gas is taken into a cylinder volume, which is
closed and opened by a suction valve, and a discharge port, through
which the working gas compressed by a reciprocating piston is
emitted toward an end use, which is closed and opened by a
discharge valve, wherein the maximum discharge pressure determined
by a compression ratio which is calculated by the ratio of the
cylinder volume in a case where the piston is located at the bottom
dead center position and the cylinder volume in a case where the
piston is located at the top dead center position, is set so as to
be compatible with the demand pressure of said gas end use.
Inventors: |
INOUE; Hiroshi;
(Yokohama-city, JP) |
Correspondence
Address: |
ROSSI, KIMMS & McDOWELL LLP.
P.O. BOX 826
ASHBURN
VA
20146-0826
US
|
Assignee: |
ANEST IWATA CORPORATION
Yokohama-shi
JP
|
Family ID: |
39255418 |
Appl. No.: |
11/862344 |
Filed: |
September 27, 2007 |
Current U.S.
Class: |
417/547 ;
417/437 |
Current CPC
Class: |
F04B 39/125 20130101;
F04B 49/16 20130101; F04B 39/1066 20130101 |
Class at
Publication: |
417/547 ;
417/437 |
International
Class: |
F04B 39/10 20060101
F04B039/10; F04B 19/22 20060101 F04B019/22; F04B 53/12 20060101
F04B053/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2006 |
JP |
2006-270046 |
Claims
1. A reciprocating compressor comprising; a suction port, through
which a working gas is taken into a cylinder, wherein the suction
port is opened/closed by a suction valve; a discharge port, through
which the working gas compressed by a reciprocating piston is
emitted toward an end use, wherein the discharge port is
opened/closed by a discharge valve; and a cylinder volume setting
mechanism that determines a cylinder volume of the cylinder;
wherein a maximum discharge pressure determined by a compression
ratio, which is calculated by the ratio of the cylinder volume in a
case where the reciprocating piston is located at the bottom dead
center position of the cylinder and the cylinder volume in a case
where the reciprocating piston is located at the top dead center
position of the cylinder, is set by the cylinder volume setting
mechanism so as to be compatible with the demand pressure of the
gas end use.
2. The reciprocating compressor of claim 1, further comprising a
cylinder-cover which puts the lid on said cylinder, wherein the
cylinder-cover is of a boxy type, and wherein within the cylinder
cover a suction chamber is connected to said suction port and is
juxtaposed with a discharge chamber connected to said discharge
port.
3. A reciprocating compressor comprising; a suction port, through
which a working gas is taken into a cylinder volume of a cylinder,
wherein the suction port is opened/closed by a suction valve; and a
discharge port, through which the working gas compressed by a
reciprocating piston is emitted toward an end use, wherein the
discharge port is opened/closed by a discharge valve; wherein said
suction port and said suction valve are at an upper part of a
suction side of a cylinder-wall of said cylinder; wherein said
discharge port and said discharge valve are at the upper part of a
discharge side of the cylinder-wall of said cylinder; and wherein a
discharge chamber is at the above-mentioned discharge side of said
cylinder-wall and is connected to said discharge port.
4. A reciprocating compressor comprising; a suction port, through
which a working gas is taken into a cylinder volume of a cylinder,
wherein the suction port is opened/closed by a suction valve; and a
discharge port, through which the working gas compressed by a
reciprocating piston within the cylinder is emitted toward an end
use, wherein the discharge port is opened/closed by a discharge
valve; wherein the suction port, which is opened and shut by said
suction valve, is placed at a top wall of said piston that faces
with said cylinder volume; wherein an inhalation passage connected
to said suction port is provided inside said piston; wherein said
discharge port and said discharge valve are at an upper part of a
cylinder-wall of said cylinder; and wherein a discharge chamber is
connected to said discharge port.
5. The reciprocating compressor of claim 1, wherein the cylinder
volume setting mechanism includes: a second cylinder volume located
by the upper part of a cylinder-wall of the cylinder, which is
connected to the cylinder volume, and a piston that is capable of
adjusting the second cylinder volume.
6. The reciprocating compressor of claim 2, wherein the cylinder
volume setting mechanism comprises a spacer located between the
cylinder and the cylinder-cover.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a reciprocating compressor,
including a suction port, through which a working gas is taken into
a cylinder room, and which is closed and opened by a suction valve,
and a discharge port, through which the working gas compressed by a
reciprocating piston is fed toward an end use, and which is
closed/opened by a discharge valve.
[0003] 2. Description of the Related Art
[0004] There are a variety of control principles that may be used
to control the pressure in a cylinder including: automatic
start/stop control or pressure switch control; load/no-load control
or unloader control; upper limit pressure release control or safety
valve control; or a combination of these controls.
[0005] In the above cylinder internal pressure control systems, a
pressure switch control device, an unloader control device or a
safety valve is required, each corresponding to pressure switch
control, unloader control or safety valve control, respectively. In
addition, an air holder and/or a gas holder is necessary so as to
maintain the operation stability of each control device.
[0006] Moreover, in a reciprocating compressor, maximum discharge
pressure Pmax depends on the compression ratio .kappa. of the
piston, where .kappa. is defined as
(Vh+Vc)/Vc
and Vh and Vc are the piston stroke volume and the cylinder dead
volume respectively. Here the cylinder dead volume means the
cylinder volume at a time when the piston is located at a top dead
center position. When the cylinder dead volume Vc is less than the
conventionally experienced value or when the compression ratio
.kappa. is more than the conventionally experienced value, the
maximum discharge pressure Pmax would exceed a permissible value,
thereby resulting in Pmax bringing excessive stress to the static
and/or running components around the cylinder room.
[0007] In order to evade the excessive rise of the maximum
discharge pressure Pmax, discharge pressure control methods have
been conventionally introduced to keep the maximum discharge
pressure to less than a permissible value.
[0008] For example, patent document WO 02/29251 discloses a method
of controlling the maximum discharge pressure. In this related
method, the maximum discharge pressure is prevented from exceeding
the permissible limit by: introducing a relief port and a relief
valve which opens and closes the relief port at a cylinder cover;
making the relief valve opened by means of a drive projection
fitted on the top of a piston at the final stage of the piston
compression stroke; and draining a part of the gas in the cylinder
outside through a relief port.
[0009] It is necessary that the maximum discharge pressure Pmax of
the compressor be kept within a service pressure so as not to cause
excessive stresses to the static and/or running components around
the cylinder room and so as to conform with the specified pressure
of the instrumentation that uses the discharged gas. In the related
art of the aforementioned patent document WO 02/29251, the maximum
discharge pressure Pmax is controlled to a target pressure so as to
meet both conditions by means of the maximum discharge pressure
control devices.
[0010] However, in the related method discussed above, it is
required to additionally introduce special parts and/or related
machining in order to control the maximum discharge pressure in a
way that the relief port, the relief valve to open/close the relief
port and the opening/closing mechanism of the valve are installed
within the cylinder cover as well as in a way that the drive
projection on the top surface of the piston is specially machined
and/or manufactured. As a result, in the related method, processing
man-hours to make the compressor and production costs of the
compressor are inevitable increased.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to realizing a
reciprocating compressor capable of holding the discharge pressure
of the compressor so as to prevent the components of the compressor
from breakage, and is also capable of always keeping the discharge
pressure of the compressor at a target pressure in order not to
violate a demand service pressure determined by the end-application
conditions or specified limitations of instruments used downstream
of the compressor, without an increase of part marks increasing
processing man-hours or increasing production costs as a
result.
[0012] According to the present invention, a reciprocating
compressor includes a suction port, through which a working gas is
taken into a cylinder room and which is closed/opened by a suction
valve, and a discharge port, through which the working gas
compressed by a reciprocating piston is fed toward an end use and
which is closed/opened by a discharge valve. Maximum discharge
pressure is determined by a compression ratio, which is calculated
by the ratio of the cylinder volume in a case where the piston is
located at the bottom dead center position and the cylinder volume
in a case where the piston is located at the top dead center
position, and the maximum discharge pressure is set so as to be
compatible with the demand pressure of the gas end use.
[0013] Specifically, the present invention provides a reciprocating
compressor that includes: a cylinder-cover, which puts a lid on a
cylinder and is of a boxy type, and a suction chamber connected to
a suction port is juxtaposed with a discharge chamber connected to
a discharge port; wherein the suction port and the suction valve
are at one side of an upper part of a cylinder-wall of the
cylinder, the discharge port and the discharge valve are at another
side of the upper part of the cylinder-wall of the cylinder, the
discharge chamber is at the discharge side of the cylinder, being
connected to discharge port, and additionally the suction valve is
placed so as to open/close the connection between the
above-mentioned discharge port and discharge chamber; wherein the
suction port, which is opened/closed by the suction valve, is
placed at a top wall of the piston, the top wall facing with the
above mentioned cylinder volume, an inhalation passage connected to
the above-mentioned suction port is prepared inside the
above-mentioned piston, the above-mentioned discharge port and the
above-mentioned discharge valve are at the upper part of the
cylinder-wall of the above-mentioned cylinder, the discharge
chamber is at the above-mentioned discharge side of the cylinder,
the chamber being connected to the above-mentioned discharge port,
and that the above-mentioned suction valve is placed so as to
open/close the connection between the above-mentioned discharge
port and discharge chamber; and wherein, outside the upper part of
the above-mentioned cylinder-wall of the above-mentioned cylinder,
is prepared a second cylinder volume, which is connected to the
aforementioned cylinder volume, and within which a piston is placed
so as to be capable of adjusting the second cylinder volume.
[0014] According to the present invention, the maximum discharge
pressure can always be held so as to be compatible with the demand
pressure of the above-mentioned gas end use, without the mechanism
described in the above-mentioned related art, namely, without
requiring a drive projection on the top surface of the piston, a
relief port and a relief valve to open/close the relief port, both
of which are prepared in the cylinder cover, and an opening/closing
device of the relief valve.
[0015] The present invention provides a way to thoroughly dispense
with the increase in the number of parts for controlling the
maximum discharge pressure of a compressor, with the increase in
the number of processing man-hours for parts, as well as with the
increase of production costs of the compressor which result
therefrom. Also, the present invention provides a way to always
keep the compressor discharge pressure at or below the target
discharge pressure, enabling the compressor discharge pressure to
be satisfactory compatible with the demand pressure of the gas end
use and enabling compressor parts to be prevented from possible
breakage.
[0016] Moreover, in case of ordinary compressors including the box
type cylinder cover which puts the lid on the above-mentioned
cylinder and within which the suction chamber connected to the
suction port is juxtaposed with the discharge chamber connected to
the discharge port, the control effectiveness, that the maximum
discharge pressure of the compressors is held within the range of
the demand service pressure, is obtained by means of inserting a
spacer into the contact surface between the cylinder and the
cylinder cover as well as by means of only adjusting the volume of
the cylinder volume. The above approach is applicable to current
compressors as they are.
[0017] In case of the compressors including: [0018] (a) a suction
port and a suction valve being located at the upper part of one
side of the cylinder-wall of the cylinder; [0019] (b) a discharge
port and a discharge valve being located at the upper part of
another side of the cylinder-wall of the cylinder; and [0020] (c) a
discharge chamber being located at the discharge side of said
cylinder, as well as being connected to the discharge port, wherein
the suction valve is placed so as to open/close the connection
between the discharge port and the discharge chamber, it becomes
possible: [0021] (i) to secure room for placing the suction valve
at the upper part of the cylinder-wall of the cylinder volume;
[0022] (ii) to allow the structure of a cylinder cover putting the
lid on the cylinder to be of simple plate type instead of the
complicated box type in a manner that a discharge chamber be at the
discharge side of the cylinder, being connected to the discharge
port.
[0023] In the above manner, the production cost of the cylinder
cover can be reduced thanks to the simplification of the structure
of the cylinder cover and a small compact compressor can be
realized with a reduced length of the piston running direction.
[0024] Moreover, since the cylinder cover can be of a plate type
and cooling fins can be easily formed on the external surface of
the cylinder cover, an improved cooling-effect of the cylinder can
be expected.
[0025] In case of a reciprocating compressor: [0026] wherein a
suction port, which is opened and shut by the suction valve, is
placed at the top wall of the piston the wall facing with the
cylinder volume; [0027] wherein an inhalation passage connected to
the suction port is prepared inside the piston; [0028] wherein the
discharge port and the discharge valve are at the upper part of the
cylinder-wall of the cylinder; and [0029] wherein a discharge
chamber is at the discharge side of the cylinder, the chamber being
connected to the discharge port, by means of [0030] (1) preparing
the discharge chamber connected to the discharge port at the
discharge side of the cylinder, and [0031] (2) placing the suction
port, which is opened and shut by the suction valve, at the top
wall of the piston, the wall facing with the cylinder volume; it
becomes possible: [0032] (a) to reduce the production cost of the
cylinder cover thanks to the simplification of the structure of the
cylinder cover; and [0033] (b) to realize a small compact
compressor with a reduced length along the piston running
direction, because the discharge chamber can be removed from the
cylinder cover and cylinder cover can be of simple plate type
instead of the complicated box type as mentioned before.
[0034] In addition, an improved cooling-effect of the cylinder can
be expected, since the cylinder cover can be of plate type and
cooling fins can be easily formed on the external surface of the
cylinder cover.
[0035] Moreover, since the suction port and the suction valve are
placed at the top wall of the piston, the wall facing with the
cylinder volume, working gas can be inhaled into the cylinder
during the piston down-stroke with the valve opened by the negative
pressure in the cylinder. During the piston up-stroke with the
valve closed by pressure rising in the cylinder, working gas can be
compressed. In this manner, the suction valve can be opened/closed
by use of reciprocating motion of the piston.
[0036] Thanks to the above manner, since it becomes possible for
the inhalated gas to be introduced from the lower part of the
cylinder-wall of the cylinder or from the lower part of the
crankcase, the degree of freedom of design gas inhalation can be
increased, namely, the number of alternative selections of gas
inhalation is increased.
[0037] In addition, in case of the compressors characterized in
that, beside the upper part of the cylinder-wall of the cylinder,
is prepared a second cylinder volume, which is connected to the
aforementioned cylinder volume, and within which a piston be placed
so as to be capable of adjusting the second cylinder volume, the
cylinder dead volume can be redefined as the sum of the original
cylinder dead volume, which is the cylinder volume at a time when
the piston is at the top dead center, and the second cylinder
volume. In this manner, the maximum discharge pressure can be
adjusted so as to be compatible with the demand pressure of gas end
use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The invention will now be described in greater detail with
reference to the preferred embodiments of the invention and the
accompanying drawings, wherein:
[0039] FIG. 1 shows a cylinder-centerline section regarding an
embodiment of the reciprocating compressor of the present
invention;
[0040] FIG. 2 shows a cylinder-centerline section regarding another
embodiment of the upper part of the reciprocating compressor of the
present invention;
[0041] FIG. 3 shows a third embodiment of the present invention
corresponding to FIG. 2; and
[0042] FIG. 4 shows a fourth embodiment of the present invention
corresponding to FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] Hereafter, the present invention will be described in detail
with reference to the embodiments shown in the figures. However,
the dimensions, materials, shape, the relative placement and so on
of a component mentioned in these embodiments shall not be
construed as limiting the scope of the invention thereto, unless
especially specific mention is placed.
[0044] FIG. 1 illustrates a reciprocating compressor in accordance
with a first embodiment of the present invention. A crankshaft 6 is
installed in and penetrates a crankcase 1. Both ends of the
crankshaft 6 are rotation-freely supported by main bearings 7. A
cylinder 3 is securely fastened to the upper part of the crankcase
1 by means of plural bolts which are not illustrated in FIG. 1.
[0045] A piston 5 is fitted inside the cylinder 3 so as to be able
to carry out reciprocating movement. The piston 5 connected to the
small end of a connecting rod 8 via a piston pin 5a, while the
large end of the connecting rod 8 is rotatably connected to the
crankshaft 6 via a bearing. A crankcase cover 2 is firmly fastened
to the crank-axial direction one side of the crankcase 1 by plural
bolts 2a.
[0046] A valve-case 4a is positioned at the upper side of the
cylinder 3 via a spacer 40. Further, a cylinder cover 4 is placed
at the upper side of the valve-case 4a via a gasket not illustrated
in the figure. The cylinder cover 4 and the valve-case 4a are
together fixed over the top face of the cylinder 3 with plural
tightening-bolts that are not illustrated in the figure.
[0047] The cylinder cover 4 is formed in the shape of box type.
Within the cylinder cover 4, a suction chamber 130 is provided
which is connected to a suction port 10, a discharge chamber 15 is
provided which is connected to a discharge port 13, and a partition
wall 130 is provided between the suction chamber and the discharge
chamber. In addition, the suction chamber 130 has a inhalation hole
12 opened for gas inhalation and the discharge chamber 15 has a
discharge hole 16 opened for gas discharge.
[0048] Further, the suction port 10 and the discharge port 13 are
positioned at the valve-case 4a. The suction port 10 is
opened/closed by means of a suction valve 11, while the discharge
port 13 is opened/closed by means of a discharge valve 14.
[0049] According to the present invention in the case of production
of the reciprocating compressor constituted as mentioned above, the
dimension C corresponding to the cylinder volume 9 in FIG. 1 is set
so that the maximum pressure in the cylinder coincides with the
demand pressure of the end use of the compressed gas which is
passed through the discharge chamber 15, where the maximum pressure
in the cylinder is decided by the compression ratio computed with a
ratio of X and Y, where X denotes the cylinder volume 9 surrounded
by the top surface of piston 5 at time in the bottom dead center
position (shown by B in FIG. 1), the interior of the cylinder 3,
and the undersurface of the cylinder cover 4 (valve-case 4a side),
and where Y denotes the cylinder volume 9 surrounded by the top
surface of piston 5 at time in the top dead center position (shown
by A in FIG. 1), the interior of the cylinder 3, and the
undersurface of the cylinder cover 4 (valve-case 4a side).
[0050] That is, by means of changing the thickness of the spacer
40, the cylinder volume 9 is adjusted so that the pressure of the
cylinder volume 9, in time when the piston 5 comes to a top dead
center A, coincides with the demand pressure of the end use of the
compressed gas. In addition, the length S shows a stroke of piston
5.
[0051] In operation, the rotational drive of the crankshaft 6 is
carried out by drive sources, such as a motor (not shown), and the
rotary motion of the crankshaft 6 is changed into the reciprocating
motion of the piston 5 through the connecting rod 8.
[0052] Gas is introduced into the cylinder 3 with the suction valve
opened during the down stroke of the piston 5 from the top dead
center A to the bottom dead center B. The gas in the cylinder 3 is
then compressed with the up stroke of the piston 5 from the bottom
dead center B to the top dead center A. The compressed gas is then
fed into the use end through a discharge hole 16 after the pressure
pulsation is relaxed in the discharge chamber 15.
[0053] The arrows show the flow of gas in FIG. 1, as described
above (the same is said of FIGS. 2-4).
[0054] Since, in the case of production of the reciprocating
compressor, the cylinder volume 9 is set so that the maximum
pressure in the cylinder, which is decided by the compression
ratio, coincides with the demand pressure of the end use equipment
of the discharged compressed-gas, the maximum pressure in the
cylinder at the top dead center A of the piston 5 does not exceed
the demand pressure (necessary working-pressure) of the end use and
the maximum pressure in the cylinder does not rise abnormally
during operation.
[0055] The above mentioned first embodiment requires the compressor
to be assembled only in the manner that the cylinder volume 9 is
set so that the maximum pressure in the cylinder, which is decided
by the compression ratio, coincides with the demand pressure for
the end use equipment of the discharged compressed-gas.
Accordingly, the first embodiment gives a way to completely
dispenses with the mechanism of the related art, for controlling
the maximum discharge pressure of the compressor toward a target
pressure, such as a drive projection on the top surface of the
piston, a relief port and a relief valve to open/close the relief
port both of which are prepared in the cylinder cover and an
opening/closing device of the relief valve. Namely, the first
embodiment enables the maximum discharge pressure to hold so as to
be compatible with the demand pressure of the above-mentioned gas
end use completely without the mechanism such as described in
aforementioned patent document.
[0056] Consequently, the first embodiment makes it possible to
realize a reciprocating compressor that is capable of holding the
discharge pressure of the compressor so as to prevent the
components of the compressor from breakage, and that is capable of
keeping always the discharge pressure of the compressor at the
target pressure in order not to violate the demand service pressure
determined by the end-application conditions or specified
limitations of instruments used downstream of the compressor,
without an increase of part marks, processing man-hours and
production costs.
[0057] Moreover, in case of an ordinary compressor comprising the
box type cylinder cover 4 which puts the lid on said cylinder 3 and
within which the suction chamber 130 connected to the suction port
10 is juxtaposed with the discharge chamber 15 connected to the
discharge port 13, the control effectiveness, that the maximum
discharge pressure of the compressors is held within the range of
the demand service pressure, is obtained by means of inserting a
spacer 40 into the contact surface between the cylinder and the
cylinder cover as well as by means of only adjusting the volume of
the cylinder volume. This embodiment is applicable to current
compressors as they are.
[0058] FIG. 2 illustrates a partial section view of the upper part
along the cylinder centerline 100 of the reciprocating compressor
concerning the second embodiment of the present invention.
[0059] In this second embodiment, horizontally by one side at the
upper part of the cylinder-wall of the cylinder 3, are prepared a
suction port 20 and a suction valve 11 which opens/closes the
suction port 20. By another side (opposite side of the suction port
20) at the upper part of the cylinder-wall, are prepared a
discharge port 23 and a discharge valve 14 which opens/closes the
discharge port 23.
[0060] Furthermore, by the discharge-side at the upper part of the
cylinder 4, is prepared a discharge chamber 24 connected to the
discharge port 23. Here, discharge valve 14 is placed so as to
open/close the connection between the discharge port 23 and
discharge chamber 24.
[0061] Here, a plate type cylinder cover 21 puts the lid on the
upper part opening of the cylinder 3 as well as the upper part
opening of the discharge chamber 24.
[0062] The other constitution of the second embodiment is the same
as that of the above first embodiment and the same part number is
used also in the FIG. 2.
[0063] The second embodiment as stated above enables a large height
of the cylinder volume 9. Accordingly, the second embodiment also
secures the space for installing the suction valve 11 at the upper
part of the cylinder-wall. Further, the second embodiment enables
the cylinder cover 21 which puts the lid on the cylinder 3 to be of
plate type by means of placing, at the discharge side of the
cylinder 3, the discharge chamber 24 connected to the discharge
port 23, while removing discharge chamber from the cylinder cover
21 and making the cylinder cover 21 only put the lid on the
cylinder 3 and the discharge chamber 24.
[0064] In the manner as mentioned above, while the structure of the
cylinder cover 21 becomes simple, the production cost of the
cylinder cover 21 can be reduced and a small compact structure can
be realized with restrained length along the cylinder center
line.
[0065] Moreover, since the cylinder cover 21 can be of plate type,
it becomes easier to form cooling fins (not shown) on the external
surface of the cylinder cover 21, and an improved cooling effect of
the cylinder 3 can be expected.
[0066] FIG. 3, corresponding to FIG. 2, shows the third embodiment
of the present invention.
[0067] In the third embodiment, on the outside surface of the upper
part of the cylinder-wall of the cylinder, are placed the discharge
port 23 and the discharge valve 14 which opens/closes the discharge
port 23, in the same manner as in the second embodiment. As to the
discharge side constitution, there is a piston suction hole 25 at
the upper part of the piston 5 of which the upper part faces the
above-mentioned cylinder volume 9. The piston suction hole 25 is
opened/closed by a suction valve 11.
[0068] In this third embodiment, the suction entrance (not shown)
of the gas is prepared at the lower part of the cylinder-wall of
the cylinder 3 or at the side face wall of the crankcase 1. During
the down stroke of the piston 5, the suction valve 11 is opened
with the aid of the negative pressure in the cylinder 3, while,
during the up stroke of the piston 5, the suction valve 11 is
closed with the aid of the pressure increase in the cylinder 3 and
the gas is compressed.
[0069] In addition, as in the above-described second embodiment,
the plate type cylinder cover 21 puts the lid on the upper part
opening of the cylinder 3 and the upper part opening of the
discharge chamber 24.
[0070] The other construction is the same as that of the above
first embodiment, and the same part as that of the above first
embodiment is quoted with the same reference number.
[0071] In case of this third embodiment, while the discharge
chamber 24 which is connected to the discharge port 23 is prepared
at the discharge side of the cylinder 3, the piston suction hole 25
is opened at the upper part of the piston 5 of which the upper part
faces the cylinder volume 9, the hole 25 being opened/closed by the
suction valve 11. Accordingly, as in the case of the second
embodiment, the cylinder cover 21 could be of plate type and of
simple structure, while having the function of only putting the lid
on the cylinder 3 and the discharge chamber 24. As a result, the
production cost of the cylinder cover 21 can be reduced and a small
compact structure of the cylinder cover can be realized, the
structure bringing restrained length of the compressor along the
cylinder-center-line.
[0072] Moreover, it would be easy to form cooling fins on the
external surface of the cylinder cover 21, and improved cooling
effect of the cylinder can therefore be expected.
[0073] Moreover, since the piston suction hole 25 and the suction
valve 11 are placed at the top wall of the piston 5, the wall
facing with the cylinder volume 9, gas can be inhaled into the
cylinder 3 during the piston 5 down-stroke with the suction valve
11 opened with the aid of the negative pressure in the cylinder 3.
During the piston 5 up-stroke with the suction valve 11 closed with
the aid of pressure rising in the cylinder 3, the gas can be
compressed. In this manner, the suction valve 11 can be
opened/closed by use of reciprocating motion of the piston 5.
[0074] By the above manner, since it becomes possible for suction
gas to be inhaled from the lower part of the cylinder-wall of the
cylinder 3 or the side face wall of the crankcase 1, the degree of
freedom of gas inhalation design is increased, namely, the number
of alternative selections of gas inhalation structure is
increased.
[0075] FIG. 4, corresponding to FIG. 2, shows the fourth embodiment
of the present invention.
[0076] In the fourth embodiment, the second cylinder volume 30
connected to the cylinder volume 9 is formed by the discharge side
of the cylinder 3, and a volume adjusting piston 31 capable of
piston movement is fitted into the second cylinder volume 30, while
a spring 32 for restoration is set between the undersurface of the
volume adjusting piston 31 and the base bottom of the second
cylinder volume 30.
[0077] The other construction is the same as that of the above
first embodiment, and the same part as that of the above first
embodiment is quoted with the same reference number.
[0078] In case of the fourth embodiment, the cylinder dead volume
can be redefined as the sum of the second cylinder volume 30 and
the original cylinder dead volume which is the cylinder volume 9 in
time when the piston 5 is at the top dead center. And the maximum
discharge pressure can be adjusted so as to be compatible with the
demand pressure of gas end use.
[0079] Moreover, since the second cylinder volume 30 connected to
the cylinder volume 9 varies with the balance of the cylinder
internal pressure force and the spring 32 force, it becomes
possible to set the total volume of the second cylinder volume 30
and the original cylinder dead volume which is the cylinder volume
9 in time when the piston 5 is at the top dead center A. Also, it
becomes possible for the maximum discharge pressure to be held
automatically so as to meet the demand pressure of gas end use.
[0080] In the above embodiments, the explanation was focused on the
reciprocating compressor which sends gas out to end use. However,
the application style is not limited to gas sending. As a matter of
course, the present invention is applicable to the reciprocating
booster compressor to have the same mechanism as the reciprocating
compressor of this invention.
[0081] The present invention makes it possible to provide a
reciprocating compressor that is capable of holding the discharge
pressure of the compressor so as to prevent the components of the
compressor from breakage, and that is capable of always keeping the
discharge pressure of the compressor at the target pressure in
order not to violate the demand service pressure determined by the
end-application conditions or specified limitations of instruments
used downstream of the compressor, without the increase of part
marks, processing man-hours and production costs.
* * * * *