Information
-
Patent Grant
-
6581624
-
Patent Number
6,581,624
-
Date Filed
Friday, October 12, 200123 years ago
-
Date Issued
Tuesday, June 24, 200321 years ago
-
Inventors
-
-
Examiners
Agents
- Wenderoth, Lind & Ponack, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 137 11901
- 137 62414
- 137 62418
- 137 104
- 137 105
- 137 99
-
International Classifications
-
Abstract
An automatic pressurized fluid switching device performs a switching using pressurized fluid rather than electrical elements, and comprises a pressurized-fluid inlet port, plural pressurized-fluid outlet ports, a switching valve for switching between outlet ports, a pilot valve for piloting the valve switching operation, and a reaction member for controlling the pilot valve in response to pressure of the pressurized fluid introduced. The pilot valve includes a first pilot unit controlled only by the reaction member, and a second pilot unit controlled by the reaction member in its initial and final stages and directly by the pressurized fluid in its middle stage, whereby the second pilot unit in the middle stage is reliably controlled even with little pressurized fluid introduced when again operated after an intermediate stoppage.
Description
TECHNICAL FIELD
This invention relates to a device for automatically switching a plurality of outlet ports from which pressurized fluid is discharged.
To be more specific, this invention relates to an automatic pressurized fluid switching device for performing a switching operation using the pressure of pressurized fluid in itself without using electrical elements.
BACKGROUND ART
As a conventional technique for automatically switching discharge of high pressure fluid such as oil and air from outlet ports, there has been known a device using electrical elements such as an electromagnetic valve and so on (cf. Japanese Patent Publication SHO 46-20414(B)). However, the conventional device entails problem such as lack of versatility, since the electrical elements have restrictions on applicability.
There has been known another device incorporating various mechanical valve systems which operate with the pressure of pressurized fluid. However, this conventional device has a possibility that a smooth switching operation cannot securely be effected when being again operated after stopping at an intermediate point of the switching action. To solve the problem noted above, the conventional device is provided with a valve mechanism or a mechanism for producing an expansion force by the pressurized fluid so as to smoothly carry out infallibly the switching operation with the expansion force of the pressurized fluid, resulting in complexity of the overall structure.
DISCLOSURE OF THE INVENTION
The present invention was made in the light of the foregoing problems, and has an object to provide an automatic pressurized fluid switching device having an excellent switching performance without using an electrical element so as not to be complicated in structure.
As set forth in claim
1
, a solution of the technical problems as described above is to provide an automatic pressurized fluid switching device comprising an inlet port for introducing pressurized fluid, a plurality of outlet ports for discharging the pressurized fluid, a switching valve disposed between the inlet port and the outlet ports for switching over the outlet ports, a pilot valve for piloting the switching operation of the switching valve, and a reaction member for controlling the pilot action of the pilot valve in response to the pressure of the pressurized fluid introduced, which is characterized in that the pilot valve is provided with a first pilot unit in which the pilot action of the pilot valve is controlled only by the reaction member, and a second pilot unit in which the pilot action of the pilot valve is controlled by the reaction member in its initial and final stages and directly by the pressurized fluid in its middle stage.
According to the solution of the technical problems described above, two lineages of the pilot action of the pilot valve for piloting the switching action of the switching valve can be constituted.
Thus, the lineages are formed of the pilot action controlled only by the reaction member in the first pilot unit and the pilot action controlled by both of the reaction member and the fluid in the second pilot unit. The pilot action in the second pilot unit is controlled by the reaction member in the initial and final stages and by the pressurized fluid in the middle stage. In other words, the pilot action in the second pilot unit in the middle stage is left free from the controlling of the reaction member.
Consequently, the pilot action in the second pilot unit in the middle stage can be securely effected even when the pressurized fluid introduced thereinto is little at the time of being again operated after stopping at the intermediate point of the switching action. Thus, smooth switching action can be performed securely. There is however no call for providing a mechanism for producing expansive power on the pressurized fluid.
As a result, a simple automatic pressurized fluid switching device having excellent switching performance can be fulfilled without using electrical elements.
The automatic pressurized fluid switching device provided as another solution of the aforesaid technical problems as set forth in claim
2
is featured in that the reaction member in the structure set forth in claim
1
comprises an operating piston mounted in a reciprocative sidable state within an operating chamber formed between the inlet port and the outlet port, each of the first pilot units of the pilot valve comprises a push rod having a front portion which protrudes into the operating chamber to come in touch with the operating piston, a flange formed in the middle of the push rod, and a pilot piston mounted at the rear portion to receive the pressure of the pressurized fluid, and each of the second pilot units of the pilot valve is formed of a sleeve fitted sidably in the rear portion side of the push rod, wherein the sleeve is shorter than the length from the flange of the push rod to the rear end thereof so as to control the pressure of the pressurized fluid applied to the switching valve.
According to this solution, the reaction member can be formed of the operating piston of a reciprocating type, which is simplest in structure. Thus, the automatic pressurized fluid switching device can be made simple in structure. Furthermore, the first and second pilot units of the pilot valve are arranged coaxially, so that they can be assembled compact. Consequently, the structure of the device can be made more simple.
As set forth in claim
3
, the other solution of the technical problems described above is featured in that the reaction member in the structure set forth in claim
1
comprises an operating piston mounted in a reciprocative sidable state within an operating chamber formed between the inlet port and the outlet port, each of the first pilot units of the pilot valve comprises a push rod having a front portion which protrudes into the operating chamber to come in touch with the operating piston, a flange formed in the middle of the push rod, and a pilot piston mounted at the rear portion to receive the pressure of the pressurized fluid, and each of the second pilot units of the pilot valve is formed of a sleeve fitted sidably in the rear portion side of the push rod, wherein the sleeve is slightly shorter than the length from the vicinity of the front portion to the rear portion of the push rod of the first pilot unit so as to control the pressure of the pressurized fluid applied to the switching valve.
According to this solution, the reaction member can be formed of the operating piston of a reciprocating type, which is simplest in structure. Thus, the automatic pressurized fluid switching device can be made simple in structure. Furthermore, the first and second pilot units of the pilot valve are arranged coaxially within a double structure, so that they can be assembled compact. Consequently, the structure of the device can be made more simple.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a sectional view showing a first embodiment of the best mode for carrying out the automatic pressurized fluid switching device according to the present invention.
FIG. 2
is an illustration of the principal portion of
FIG. 1
, showing the sequence of operation of the device in the order of (A) to (C).
FIG. 3
shows the state of finishing the operation of FIG.
2
.
FIG. 4
shows the state of finishing the operation of the principal portion of the counterpart of FIG.
2
.
FIG. 5
is a sectional view showing a second embodiment of the best mode for carrying out the automatic pressurized fluid switching device, showing the sequence of operation of the device in the order of (A) to (C).
BEST MODE FOR CARRYING OUT THE INVENTION
The best mode for carrying out the automatic pressurized fluid switching device according to the invention will be described hereinafter with reference to the accompanying drawings.
FIG.
1
through
FIG. 4
show a first embodiment of the invention.
The illustrated device comprises one inlet port
1
for introducing pressurized fluid A, and two outlet ports
2
and
3
for discharging the pressurized fluid A.
There is adopted a switching valve
4
of a spool type having a shaft
4
a
and lands
4
b
. The shaft
4
a
of the switching valve
4
has both end portions inserted into pressure chambers
6
and
7
formed in a housing
5
and supported by the housing
5
in a sidable state. Each of the end portions of the shaft
4
a
receives the pressure of pressurized fluid selectively supplied to one of the pressure chambers
6
and
7
at a time. The lands
4
b
are in disjunctive contact with seats
8
formed within the housing
5
, so that two main passages
9
and
10
communicating with the inlet port
1
and outlet ports
2
and
3
can be intermittently switched over to each other.
The two main passages
9
and
10
communicate with an operating chamber
11
formed in the housing
5
.
In the operating chamber
11
, there is contained an operating piston
12
serving as a reaction member which is sidably moved by the pressure of the pressurized fluid A. The two main passages
9
and
10
are divided by the operating piston
12
within the operating chamber
11
.
On both sides of the operating piston
12
(operating chamber
11
), there are disposed a pair of pilot valves
13
and
14
.
The pilot valves
13
and
14
have first pilot units
13
a
and
14
a
, and second pilot units
13
b
and
14
b
, respectively. The first pilot units
13
a
and
14
a
comprise push rods
13
aa
and
14
aa
each having a round cross-section, which rods each have a front portion protruding into the operating chamber
11
to come in touch with the operating piston
12
, plate-like flanges
13
ab
and
14
ab
formed in the middle of the push rod
13
aa
, and pilot pistons
13
ac
and
14
ac
connected to or brought in contact with the rear portions of the push rods
13
aa
and
14
aa
. The second pilot units
13
b
and
14
b
of the pilot valve are each formed of a sleeve fitted slidably in the rear portion side of the push rod, wherein the sleeve is shorter than the length from the flange
13
ab
or
14
ab
of the push rod
13
aa
or
14
aa
to the rear end thereof. In the rear portion sides of the pilot units, there are formed discharge ports
13
ba
and
14
ba.
The pilot pistons
13
ac
and
14
ac
of the first pilot units
13
a
and
14
a
are opposed to pilot passages
15
and
16
leading to the main passages
9
and
10
. Consequently, the pilot pistons
13
ac
and
14
ac
each receive the pressure of the pressurized fluid A in the main passages
9
and
10
.
The discharge ports
13
ba
and
14
ba
of the second pilot units
13
b
and
14
b
can selectively communicate with discharge passages
17
and
18
leading to the outside of the housing
5
or pressure release passages
21
and
22
diverged from pressure passages
19
and
20
. Incidentally, the pressure passages
19
and
20
are connected with voids formed in the front end sides of the second pilot units
14
b
and
13
b
of the opposed pilot valves
14
and
13
.
With passages formed between the pressure passages
20
and
19
and the pressure release passages
21
and
22
, pressure supplying passages
23
and
24
, which always communicate with the inlet port
1
, are connected.
The pressure passages
20
and
19
and the pressure supplying passages
23
and
24
are arranged so as to communicate with each other through the voids formed in the front end sides of the second pilot units
13
b
and
14
b
when the second pilot units
13
b
and
14
b
of the pilot valve
13
move backward.
According to this embodiment, the device can be made simple in structure because it has no need of relying on any electrical element such as an electromagnetic valve nor causing the pressurized fluid to produce an expansion force. Thus, a highly versatile pressurized fluid switching device without having restrictions in applicability can be fulfilled.
As shown in
FIG. 1
, the switching operation in this embodiment is carried out by introducing the pressurized fluid A into the right main passage
10
communicating with the inlet port
1
to forcibly slide the operating piston
12
leftward within the operating chamber
11
in the state of switching the switching valve
4
rightward (in the drawing). Thus, the pressurized fluid A is discharged from the left outlet port
2
. The light outlet port
3
is closed by the switching valve
4
.
At this time, the operating piston
12
thrusts the push rod
13
aa
of the first pilot unit
13
a
of the left pilot valve
13
in the initial stage as shown in FIG.
2
(B). Thus, the entire first pilot unit
13
a
moves backward. However, the second pilot unit
13
b
is remained in its rest state slidably pushed by the push rod
13
aa
. As a result, between the pilot piston
13
ac
of the first pilot unit
13
a
and the rear end side of the second pilot unit
13
b
, there is formed a space S.
The subsequent sliding motion of the operating piston
12
involves moving the second pilot unit
13
b
by means of the flange
13
ab
of the first pilot unit
13
a
. Consequently, the entire pilot valve
13
(first pilot unit
13
a
and second pilot unit
13
b
) integrally moves backward.
The further subsequent sliding motion of the operating piston
12
in its middle stage involves introducing the pressurized fluid A into the front side chamber of the second pilot unit
13
b
by moving the front end of the second pilot unit
13
backward behind the pressure supplying passages
23
, as shown in FIG.
2
(C). Consequently, the second pilot unit
13
b
is moved backward by the pressurized fluid A at higher speed than the first pilot unit
13
a
. The backward movement of the second pilot unit
13
b
slows down due to collision with the pilot piston
13
ac
of the first pilot unit
13
a
(disappearance of the space S).
The further sliding motion of the operating piston
12
continues to push the push rod
13
aa
of the first pilot unit
13
a
in the final stage. The second pilot unit
13
b
is also continued to move backward due to the pressure of the pressurized fluid A. Consequently, the entire pilot valve
13
(first and second pilot units
13
a
and
13
b
in one body) moves backward.
When the operating piston
12
changes from the state shown in FIG.
2
(C) to the state of stopping as shown in
FIG. 3
, the pressurized fluid A introduced into the front end side of the second pilot unit
13
b
through the pressure supplying passages
23
flows into the pressure passage
20
and fills up the right pressure chamber
7
, thus to push the right side end portion of the shaft
4
a
of the switching valve
4
. Consequently, the switching valve
4
which assumes its right position is automatically turned to its left position.
That is to say, the operating piston
12
is pushed by the pressurized fluid A introduced into the left main passage
9
communicating with the inlet port
1
, thus to move rightward within the operating chamber
11
. As a result, the pressurized fluid A is discharged from the right outlet port
3
. At this time, the left outlet port
2
is closed by the switching valve
4
.
At the time of switching the switching valve
4
, the right pilot valve
14
moves forward by the pressure of the pressurized fluid A from the pilot passage
16
communicating with the right main passage
10
, as shown in FIG.
4
. Thus, the right pressure release passage
22
is not connected with the discharge port
14
ba
of the second pilot unit
14
b
, and thus, isolated from the discharge passage
18
. As a result, pressure loss of the pressurized fluid A filled in the right pressure chamber
7
can be prevented.
On the other hand, the left pressure release passage
21
is connected with the discharge port
13
ba
of the second pilot unit
13
b
to communicate with the discharge passage
17
, as shown in FIG.
3
. As a result, the pressurized fluid A filled in the left pressure chamber
6
is discharged from the discharge passage
17
, to decrease resistance of the pressurized fluid A applied to the left side end portion of the shaft
4
a
of the switching valve
4
.
FIG. 5
illustrates the second embodiment of the invention.
The pilot valves
13
and
14
in this illustrated embodiment are modified from those of the foregoing first embodiment.
The first pilot units
13
a
and
14
a
of the pilot valves
13
and
14
in this embodiment are not provided with the flanges
13
ab
and
14
ab
found in the first embodiment.
The second pilot units
13
b
and
14
b
of the pilot valves
13
and
14
in this embodiment are each formed of a sleeve, which has length slightly shorter than that from the front end to the rear end of the respective push rods
13
aa
and
14
aa
of the first pilot unit
13
a
and
14
a
. The front end portions
13
bb
and
14
bb
of the respective sleeves are made small in diameter and brought in contact with the operating piston
12
within the operating chamber
11
.
In this manner, the pilot units
13
a
and
14
a
and the second pilot units
13
b
and
14
b
can be made compact.
Besides, the front end portions
13
bb
and
14
bb
of the second pilot unit can bring about the same function and effect as the flanges
13
ab
and
14
ab
of the first pilot units
13
a
and
14
a
in the first embodiment described above.
Furthermore, the passages connected with the pressure passages
19
and
20
, pressure supplying passages
23
and
24
, inlet port
1
, and outlet ports
2
and
3
may be arbitrarily modified in various ways.
INDUSTRIAL APPLICABILITY
The present invention is applicable to all sorts of pressurized fluid such as oil, air and gas.
The switching mechanism for discharging the pressurized fluid according to the invention can be used for not only a reciprocating drive device for a fluid pressure cylinder, but also a fluid pressure pump, a fluid pressure compressor and the like.
Claims
- 1. An automatic pressurized fluid switching device comprising an inlet port for introducing pressurized fluid, a plurality of outlet ports for discharging the pressurized fluid, a switching valve disposed between said inlet port and said outlet ports for switching over said outlet ports, a pilot valve for piloting switching operation of said switching valve, and a reaction member for controlling pilot action of said pilot valve in response to pressure of the pressurized fluid introduced, characterized in that said pilot valve is provided with a first pilot unit in which the pilot action of said pilot valve is controlled only by said reaction member, and a second pilot unit in which the pilot action of said pilot valve is controlled by said reaction member in its initial and final stages and directly by the pressurized fluid in its middle stage.
- 2. An automatic pressurized fluid switching device according to claim 1, wherein said reaction member comprises an operating piston mounted in a reciprocative sidable state within an operating chamber formed between said inlet port and said outlet ports, each of said first pilot units of said pilot valve comprises a push rod having a front portion which protrudes into said operating chamber to come in touch with said operating piston, a flange formed in the middle of said push rod, and a pilot piston mounted at the rear portion to receive the pressure of the pressurized fluid, and each of said second pilot units of said pilot valve is formed of a sleeve fitted sidably in the rear portion side of said push rod, said sleeve being shorter than length from said flange of said push rod to the rear end thereof so as to control the pressure of the pressurized fluid applied to said switching valve.
- 3. An automatic pressurized fluid switching device according to claim 1, wherein that the reaction member comprises an operating piston mounted in a reciprocative sidable state within an operating chamber formed between said inlet port and said outlet ports, each of said first pilot units of said pilot valve comprises a push rod having a front portion which protrudes into said operating chamber to come in touch with said operating piston, a flange formed in the middle of said push rod, and a pilot piston mounted at the rear portion to receive the pressure of the pressurized fluid, and each of said second pilot units of said pilot valve is formed of a sleeve fitted sidably in the rear portion side of said push rod, said sleeve being slightly shorter than length from the vicinity of the front portion to the rear portion of said push rod of said first pilot unit so as to control the pressure of the pressurized fluid applied to said switching valve.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/JP99/01959 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/61949 |
10/19/2000 |
WO |
A |
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3260212 |
Johnson |
Jul 1966 |
A |
3791768 |
Wanner |
Feb 1974 |
A |
4572331 |
Powell et al. |
Feb 1986 |
A |
Foreign Referenced Citations (4)
Number |
Date |
Country |
28-5844 |
Nov 1953 |
JP |
51-24480 |
Feb 1976 |
JP |
60-263708 |
Dec 1985 |
JP |
01-250604 |
Oct 1989 |
JP |