Power plants – Pressure fluid source and motor – With control means for structure storing work driving energy
Reexamination Certificate
1999-11-02
2002-10-08
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
With control means for structure storing work driving energy
C060S484000
Reexamination Certificate
active
06460332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recovery apparatus for recovering the energy of the return pressure oil flowing out of a hydraulic actuator and to a recovery/regeneration apparatus for recovering the energy of the return pressure oil and reusing the recovered energy during the driving of the aforementioned hydraulic actuator.
2. Description of the Related Art
Recovery/regeneration apparatus for recovering the energy of the return pressure oil flowing out of a hydraulic actuator, and reusing the recovered energy during the driving of the aforementioned hydraulic actuator are already common knowledge. Such recovery/regeneration apparatus are incorporated and mounted in the hydraulic circuits of hydraulic shovels and other types of construction machinery, for example.
For example, Japanese Patent Publication No. 33922/1991 discloses the system for the recovery and reuse of pressure oil depicted in FIG.
7
.
Specifically, the hydraulic circuit depicted in
FIG. 7
is such that the pressure oil discharged from a hydraulic pump
32
is fed to a hydraulic cylinder
33
via a pressure oil supply line
42
, whereby the hydraulic cylinder
33
is actuated and a load
34
(for example, a piece of machinery) is operated.
Pressure oil flows out of the hydraulic cylinder
33
if the supply of pressure oil from the hydraulic pump
32
to the hydraulic cylinder
33
is stopped. As shown by arrow A
1
, the return pressure oil flowing out of the hydraulic cylinder
33
enters a pressure converter
36
via a line
35
. The pressure converter
36
comprises two hydraulic pump motors
37
and
38
.
The hydraulic pump motor
37
is rotated by the return pressure oil that enters the hydraulic pump motor
37
. The rotation of the hydraulic pump motor
37
actuates the hydraulic pump motor
38
. The pressure oil is therefore discharged from the hydraulic pump motor
38
, as shown by arrow A
2
. The pressure oil discharged from the hydraulic pump motor
38
is prevented from flowing back into the pressure oil supply line
42
by a check valve
41
, and is fed to an accumulator
40
via a line
39
. In the accumulator
40
, the energy of the pressure oil is stored by being converted to the compression energy of the gas sealed inside.
The energy of pressure oil is thus recovered and stored. The following operation is performed to regenerate the energy of pressure oil.
Specifically, actuating the hydraulic pump
32
causes the pressure oil discharged from the hydraulic pump
32
to be fed to the pressure oil supply line
42
, as shown by arrow B
1
. Here, the pressure oil stored in the accumulator
40
flows into the hydraulic pump motor
38
in addition to the pressure oil discharged from the hydraulic pump
32
, as shown by arrow B
2
. The hydraulic pump motor
38
is therefore rotated by the combined energy of the pressure oil stored in the accumulator
40
and the actuation energy of the hydraulic pump
32
.
The rotation of the, hydraulic pump motor
38
actuates the hydraulic pump motor
37
. Pressure oil is therefore discharged from the hydraulic pump motor
37
and fed to the hydraulic cylinder
33
, as shown by arrow B
3
. Consequently, the hydraulic cylinder
33
is expanded, and the load
34
is operated.
With this hydraulic circuit, however, energy reuse is limited to a single hydraulic cylinder
33
when the energy of the return pressure oil from this hydraulic cylinder
33
is recovered, stored in pressurized form, and regenerated.
In view of this, a hydraulic circuit has been proposed to allow energy to be reused in an assembly composed of a plurality of hydraulic actuators when the energy of the return pressure oil from these hydraulic actuators is recovered, stored in pressurized form, and regenerated. The present applicants have already filed International Application PCT/JP97/03416.
This hydraulic circuit is depicted in FIG.
8
(
a
).
Specifically, the hydraulic circuit depicted in FIG.
8
(
a
) is substantially configured such that a plurality of hydraulic actuators (that is, a hydraulic cylinder
7
and a hydraulic motor
29
) are actuated, and the corresponding loads
8
and
10
(for example, pieces of machinery) are operated according to a procedure in which the pressure oil discharged from a hydraulic pump
2
is fed to the hydraulic cylinder
7
and hydraulic motor
29
via a pressure oil supply line
3
.
Line
16
of the hydraulic circuit depicted in FIG.
8
(
a
) is provided with a check valve
17
. A detailed structure of this check valve
17
is depicted in FIG.
8
(
c
). As shown in FIG.
8
(
c
), the check valve
17
is a magnetic switching valve that is urged to a closed position
17
a
or open position
17
b
by the application of an ON or OFF electric current command to a solenoid
17
c
via an electric signal line. When the check valve
17
is in the closed position
17
a
, the flow of pressure oil into the check valve
17
is stopped, and when the check valve
17
is in the open position
17
b
, the pressure oil flows in and out of the check valve
17
in a single direction. A check valve
22
provided to a line
21
is configured in the same manner as the check valve
17
.
In addition, a pressure-accumulating valve
54
is provided to the line
55
of the hydraulic circuit depicted in FIG.
8
(
a
). A detailed structure of this pressure-accumulating valve
54
is depicted in FIG.
8
(
b
). As shown in FIG.
8
(
b
), the pressure-accumulating valve
54
is a magnetic switching valve that is urged to a closed position
54
a
or open position
54
b
by the application of ON or OFF electric current commands to a solenoid
54
c
via an electric signal line. When the pressure-accumulating valve
54
is placed in the closed position
54
a
, the flow of pressure oil into the pressure-accumulating valve
54
is stopped, and when the pressure-accumulating valve
54
is placed in the open position
54
b
, the pressure oil flows in and out of the pressure-accumulating valve
54
in both directions.
Stopping the supply of pressure oil to the hydraulic cylinder
7
and hydraulic motor
29
through the discharge port
2
b
of the hydraulic pump
2
contracts the hydraulic cylinder
7
by the gravity of the load
8
, and causes the pressure oil to flow out of the hydraulic cylinder
7
via a line
6
b
. Similarly, the hydraulic motor
29
is actuated by the gravity of the load
10
, and pressure oil is caused to flow out of the hydraulic motor
29
via a line
9
a.
The return pressure oil flowing out of the hydraulic cylinder
7
and hydraulic motor
29
enters a selection circuit
13
. The selection circuit
13
comprises two check valves
14
and
15
.
The result of the aforementioned return pressure oil entering the selection circuit
13
is that, of the return pressure oil flowing out of the hydraulic cylinder
7
and hydraulic motor
29
, the oil pressurized to a higher degree is selected and allowed to flow out into the line
16
. Here, the check valve
17
is in the open position, and the selected return pressure oil is allowed to enter a pressure converter
50
. The pressure converter
50
comprises two hydraulic pump motors
51
and
52
.
The return pressure oil flowing into the hydraulic pump motor
51
rotates the hydraulic pump motor
51
. The hydraulic pump motor
52
is actuated by the rotation of the hydraulic pump motor
51
. The pressure oil from the hydraulic pump motor
52
is therefore discharged into a line
53
. Here, the pressure-accumulating valve
54
is in the open position, and the pressure oil discharged from the hydraulic pump motor
52
is fed to the accumulator
40
via a line
55
. In the accumulator
40
, the energy of the pressure oil is stored by being converted to the compression energy of the gas sealed inside. The pressure-accumulating valve
54
is in the closed position, and the high-pressure oil stored in the accumulator
40
is kept in without being allowed to flow out.
The energy of pressure oil is thus recovered and stored. The following operation is performed to regenerate the energ
Maruta Kazuhiro
Yoshida Nobumi
Komatsu Ltd.
Ryznic John E.
LandOfFree
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