Power plants – Pressure fluid source and motor – With control means for structure storing work driving energy
Reexamination Certificate
2001-06-13
2002-04-30
Lopez, F. Daniel (Department: 3745)
Power plants
Pressure fluid source and motor
With control means for structure storing work driving energy
C060S417000, C060S419000
Reexamination Certificate
active
06378301
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hydraulic oil recovery/reutilization system which accumulates a high pressure fluid by an energy of a pressurized fluid returned from a hydraulic actuator in a construction machine, such as a power shovel or the like and re-uses an accumulated high pressure fluid as an actuation energy of an actuator.
BACKGROUND ART
As a power shovel, there has been known one, in which an upper pivotal body is provided on a lower vehicular body having a traveling body, for pivotal motion by a pivoting hydraulic motor, a boom is mounted on the upper pivotal body for vertical rocking motion by means of a boom cylinder, an arm is mounted on the boom for vertical rocking motion by means of an arm cylinder, and a bucket is mounted on the arm for vertical swing motion by means of a bucket cylinder.
The foregoing pivoting hydraulic motor, the boom cylinder, the arm cylinder and the bucket cylinder are actuated by supplying a discharged pressurized fluid of a hydraulic pump to one chamber and draining the pressurized fluid of another chamber to a tank, by switching direction switching valves.
For example, the discharged pressurized fluid of the hydraulic pump is supplied to an expansion chamber of the boom cylinder by the direction switching valve for the boom, and in conjunction therewith, the pressurized fluid in a compression chamber is drained for actuating the boom cylinder for expansion, and the discharged pressurized fluid of the hydraulic pump is supplied to the compression chamber of the boom cylinder, and in conjunction therewith, the pressurized fluid in the expansion chamber is drained for actuating the boom cylinder for compression.
As set forth above, since the pressurized fluid returned from the pivoting hydraulic motor, the boom cylinder, the arm cylinder and the bucket cylinder is drained to the tank, an energy of the returning pressurized fluid cannot be used.
For example, in the case of a compression operation of the boom cylinder, a pressure is generated in the pressurized fluid returned from the expansion chamber due to the weight of the boom, the arm and the bucket. However, since the returning pressurized fluid is drained to the tank, the pressure (energy) of the returning pressurized fluid cannot be re-used. On the other hand, there has been proposed an apparatus for recovering and re-using the energy of the returning pressurized fluid of the hydraulic actuator. For example, there has been known a pressurized fluid recovering/reutilization system disclosed in Japanese Examined Patent Publication No. Heisei 3-33922.
As shown in
FIG. 1
, the pressurized fluid recovering/reutilization system is constructed by connecting a chamber
2
of a single action cylinder
1
as an actuator to a port
4
of a first pump motor
3
, connecting a port
6
of a second pump motor
5
mechanically coupled with the first pump motor
3
to a pressurized fluid supply circuit
7
, connecting the pressurized fluid supply circuit
7
to the hydraulic pressure source via a check valve
8
and to a pressure accumulator
9
. With this system, by supplying a pressurized fluid of the hydraulic pressure source to the pressurized fluid supply circuit
7
, the second pump motor
5
performs motoring operation to drive the first pump motor
3
. Then, the first pump motor
3
performing pumping operation to supply the pressurized fluid to the chamber
2
of the single action cylinder
1
to actuate the single action cylinder
1
for expansion.
When supply of the pressurized fluid to the pressurized fluid supply circuit
7
is terminated, the single action cylinder
1
is actuated for compression by an external load to generate a pressure in the returning pressurized fluid of the chamber
2
to drive the first pump motor
3
for motoring operation.
By this, the second pump motor
5
performs a pumping operation to generate a high pressure fluid to the pressurized fluid supply circuit
7
. The flow of the high pressure fluid is blocked by the check valve
8
and the pressure is accumulated in the pressure accumulator
9
.
Then, when the single action cylinder
1
is operated again for expansion by supplying the pressurized fluid to the pressurized fluid supply circuit
7
, the high pressure fluid accumulated in the pressure accumulator
9
drives the second pump motor
5
. Thus, the first pump motor
3
performs pumping operation to supply high pressure fluid to the chamber
2
to enable re-using of the pressurized fluid (energy) accumulated in the pressure accumulator
9
.
The foregoing system accumulates high pressure fluid by energy of the returning pressurized fluid of the chamber
2
of the single action cylinder
1
to supply the pressurized fluid to the chamber
2
of the single action cylinder
1
by the accumulated high pressure fluid again. Thus, the accumulated high pressure fluid is re-used only for the single action cylinder and cannot be re-used for other actuators.
Therefore, an object of the present invention is to provide a pressurized fluid recovering and reutilization system which can solve the problem set forth above.
DISCLOSURE OF THE INVENTION
The first invention is a pressurized fluid recovery/reutilization system characterized by supplying a pressurized fluid of high pressure to a hydraulic pressure source by operating a pressure converter
18
constructed with a first pump motor
16
and a second pump motor
17
which are mechanically coupled by an energy of a pressurized fluid returned from an actuator actuated by the pressurized fluid of the hydraulic power source.
By the first invention, since the pressurized fluid of high pressure is supplied to the hydraulic pressure source by the energy of the returning pressurized fluid of the actuator, the recovered returning pressurized fluid of the actuator can be reused for actuation of another actuator.
The second invention is a pressurized fluid recovery/reutilization system which comprises a primary hydraulic pump
10
supplying a pressurized fluid returned from an actuator, a first circuit
22
supplied the returning pressurized fluid from the actuator, a first pump motor
16
connected to said first circuit
22
, a variable displacement type second pump motor
17
mechanically coupled with said first pump motor
16
and connected to a second circuit
25
, a third circuit
29
communicating said first circuit
22
and a discharge passage
11
of said primary hydraulic pump
10
, a pressure accumulator
27
provided in said second circuit
25
, and a reproduction valve
30
switching said third circuit between a state permitting the flow of a pressurized fluid and a state blocking the flow.
By second invention, by switching the flow of the pressurized fluid in the third circuit is switched into blocking state by the reproduction valve
30
, the first pump motor
16
is operated for motoring operation by the returning pressurized fluid to cause pumping operation of the second pump motor
17
. Thus, the pressurized fluid of high pressure can be accumulated in the pressure accumulator
27
.
By switching the third circuit
29
to permit the flow of the pressurized fluid by the reproduction valve
30
, the second pump motor
17
is operated to perform motoring operation by the accumulated pressurized fluid of high pressure to cause pumping operation of the first pump motor
16
to supply the discharge passage
11
of the primary hydraulic pump
10
via the third circuit
29
by discharging fluid to the first circuit
22
.
By this, the energy of the returning pressurized fluid of the actuator can be reused for actuation of another actuator.
On the other hand, when the second pump motor
17
performs motoring operation, an output torque of the second pump motor
17
, namely a torque for driving the first pump motor
16
, is varied by increasing and decreasing of the displacement of the second pump motor
17
. Thus, by pumping operation of the first pump motor
16
, the pressure in the first circuit
22
can be increased and decreased.
By this, the pressure of the first circuit
22
is set to be equ
Endo Hiroshi
Muruta Kazuhiro
Yoshida Nobumi
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Komatsu Ltd.
Lazo Thomas E.
Lopez F. Daniel
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