JP3129495B2 - Potential energy recovery device for lifting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lifting and lowering work machine for performing work by lifting and lowering a work machine such as a construction machine such as a loader-type backhoe and a loading machine such as a forklift.
In particular, the present invention relates to a potential energy recovery device for a lifting and lowering working machine for recovering potential energy of a working machine in a lifting state.

[0002]

2. Description of the Related Art As shown in FIG. 9, a conventional lifting / lowering working machine, for example, a working machine in a backhoe has a boom cylinder a, b in addition to two boom cylinders a, b. b, the bottom side of the assist cylinder b is connected to a pressure accumulator d, and the potential energy of the working machine stored in the assist cylinder c is accumulated in the pressure accumulator d as pressure and collected. Was.

[0003]

In the above-mentioned conventional apparatus for recovering potential energy of a working machine, in addition to, for example, two boom cylinders a and b for lifting and lowering the working machine, the apparatus is dedicated to recovering potential energy. Since the assist cylinder c must be provided, the boom and the turning frame are different from those of the standard specification vehicle, the structure is complicated, and the cost is high because each cylinder is required separately.

[0004] The present invention has been made in view of the fact described above, the potential energy of the working machine in a single lift cylinder of such conventional multiple boom cylinder can recover, potential energy recovered conventionally used A special cylinder is not required, the structure is simple, the cost can be reduced, and the assisting operation by recovering the potential energy is released under a predetermined condition to lower the working machine.
It is an object of the present invention to provide a potential energy recovery device for a lifting / lowering working machine that can use the potential energy of the working machine as it is and can perform a lowering operation of the working machine with all lifting / lowering cylinders as necessary. Things.

[0005]

In order to achieve the above object, a first aspect of the present invention is directed to a potential energy recovery apparatus for a working machine, wherein at least one of a plurality of lifting cylinders for lifting and lowering the working machine is provided. The bottom side and the rod side of the lifting cylinder are connected to a hydraulic pump via a lifting operation valve, and at least one other lifting cylinder of the lifting cylinder is used as an assist cylinder, and the bottom side of the assist cylinder is connected via a check valve. connected to the lift operation valve, also while connected to the accumulator through a pilot check valve, connected to the tank side through the relief valve, connects the rod side to the tank, further, the bottom side of the assist cylinder pilot
Pilot check on the bottom side between the check valve
There is a communication position to communicate with the valve side and a drain position to drain.
The assist release valve is interposed . The potential energy recovery device for a working machine according to the second invention is
In the potential energy recovery device for a working machine according to the first aspect , the assist release valve has a port for supplying pressure oil from a pump to a rod side of the assist cylinder when the assist release valve is at a drain position. Has become.

[0006]

[Work] In the first aspect of the invention, by switching the lifting / lowering operation valve to the rising side, pressure oil is supplied to the bottom side of each lifting / lowering cylinder, and the working machine is lifted by all the lifting / lowering cylinders. Be moved. Then, by switching the lifting / lowering operation valve to the lowering side, the lifting / lowering cylinder connected to the lifting / lowering operation valve on the rod side is shortened by the pressure oil supplied from the lifting / lowering operation valve, and the work machine is lowered. Then, the assist cylinder at this time is shortened by the lowering operation of the working machine, the pressure oil on the bottom side at this time is stored in the pressure accumulator, and the pressure oil stored in the pressure accumulator is used at the next ascent operation , Further
In addition, during the lowering operation of the work machine, the assist release valve is switched to the drain position, whereby the bottom side of the assist cylinder is connected to the tank side, so that the operation of storing potential energy when the work machine is lowered is eliminated, and Is lowered without resistance. In the second invention, when the assist release valve is switched to the drain position, the rod side of the assist cylinder is connected to the lifting operation valve side, and this assist cylinder has the same function as another normal lifting cylinder. Become.

[0007]

[Embodiment] An embodiment of the present invention will be described with reference to the drawings. This embodiment is a case of a backhoe, and FIG.
That 1 rotating frame 2 is undulating freely Kururuazuka been boom to the rotating frame 1, arm is connected to the distal end of the boom 2 3, 4 is a bucket. Reference numerals 5a and 5b denote first and second boom cylinders for raising and lowering the boom 2. The base ends of the cylinders are connected to the revolving frame 1, and the tip of the piston rod is connected to the boom 2. 6 is an arm cylinder, 7 is a bucket cylinder. Of the two boom cylinders, ie, the first and second boom cylinders 5a and 5b, the bottom side and the rod side of the first boom cylinder 5a are connected to a hydraulic pump 9 via a boom operation valve 8.
And the bottom side of the second boom cylinder 5b is connected to the bottom side of the first boom cylinder 5a and the boom operation valve 8 via a check valve 10,
The rod side is open to the tank side. The circuit between the bottom side of the second boom cylinder 5b and the check valve 10 is connected to the tank side via a relief valve 11 and connected to the pressure accumulator 13 via a pilot check valve 12. is there. The boom operation valve 8 is configured to be switched by a pilot pressure selectively actuated by a pilot operation valve device 14. It is connected to the working part. In addition,
16a and 16b are suction safety valves.

In the above configuration, the pilot operating valve device 14 is operated to apply a pilot pressure to the pilot circuit 15 a on the boom raising side, so that the boom operating valve 8 is at the boom raising position A, and the hydraulic oil from the hydraulic pump 9 is Is supplied to the bottom sides of the first and second boom cylinders 5a and 5b, which extend, and the boom 2 rises. At this time, the pressure oil on the rod side of the first boom cylinder 5a is drained to the tank side via the boom operation valve 8, but the pressure oil on the rod side of the second boom cylinder 5b is directly drained to the tank side. . On the other hand, by operating the pilot operating valve device 14 to apply pilot pressure to the pilot circuit 15b on the boom lowering side, the boom directional switching valve 8 is at the boom lowering position B, and the hydraulic oil from the hydraulic pump 9 is in the first position. It is supplied to the rod side of the boom cylinder 5a and is shortened, and the boom 2 descends. At this time, the second boom cylinder 5b
Is shortened by the descending boom 2. At this time, the pressure oil on the bottom side of the second boom cylinder 5b is prevented from flowing in the drain direction by the check valve 10, and flows into the accumulator 13 through the pilot check valve 12, thereby , The potential energy of the boom 2 is stored as pressure oil. The pressure at this time is the relief valve 11
Set by. In the above state, the pilot operation valve device 14 is operated to move the boom operation valve 8 to the boom raising position A.
When the boom 2 is raised and the boom 2 is raised, the pressure oil from the pressure oil pump 9 is supplied to the bottom side of the first and second boom cylinders 5a and 5b to extend the two boom cylinders 5a and 5b. At this time, the pressure of the pilot circuit 15a on the boom raising side of the boom operation valve 8 acts on the pilot check valve 12 to open it, so that the pressure oil stored in the accumulator 13 is released from the bottom of the second boom cylinder 5b. And the extension movement of the second boom cylinder 5b is assisted by the accumulated pressure energy,
The potential energy due to the lowering is recovered.

In the above embodiment, the pilot which opens between the bottom circuit of the second boom cylinder 5b and the pressure accumulator 13 by the pressure of the pilot circuit 15a on the boom raising side of the boom directional switching valve 8 is provided. Although an example in which the check valve 12 is interposed is shown, as shown in FIG. 2, a switching valve 18 which opens by the pressure of both pilot circuits 15a and 15b of the boom directional switching valve 8 is interposed. Some have been made.

[0010] A first aspect of the present invention is apparatus having the above-described structure of the present invention
FIG. 3 and FIG. 4 show an embodiment thereof. That is, in the apparatus having the above configuration, the loader such as a loader or a forklift has no problem.However, in a machine such as a backhoe that performs downward excavation using the weight of the working machine, the working machine is moved from the upper loading height. When lowering the work machine to the downward excavation posture, if the switching valve 8 is operated and the pressure oil on the bottom side of the boom cylinder is drained to the tank, the work machine is lowered by its own weight. At this time, low pressure oil may be supplied from the pump so that the rod side does not become negative pressure. At this time, the pressure oil on the bottom side of the assist cylinder is collected by the pressure accumulator 13 and is utilized at the time of the next work machine raising operation. By the way, when the machine enters the excavation state after descending ,
In the device , the pressurized oil is in a state where the pressurized oil is recovered to the maximum,
The bottom side of the assist cylinder is at a high pressure, and the working machine is in a floating state due to the pressure, so that excavation using the weight of the working machine (excavation with a moment l × W) cannot be performed (see FIG. 8). Therefore, when an assist release valve 19 is interposed between the pilot check valve 12 and the circuit on the bottom side of the assist cylinder, when a certain pressure or more is applied to the rod side of the boom cylinder in the downward excavation state, this valve is switched. Since the bottom circuit of the assist cylinder is drained to the tank and the working machine is about to fall by its own weight, excavation using the working machine's own weight becomes possible. That is, on
In the device having the above structure, the potential energy of the work implement at the time of the lowering operation of the boom 2 is reduced to the maximum value of the potential energy of the accumulator
3, the excavation using the weight of the working machine cannot be performed. The first invention is an improvement of the first invention . Hereinafter, this embodiment will be described with respect to portions different from the configuration shown in FIG . In the embodiment of the first invention shown in FIG. 3, an assist release valve 19 having a communication position C and a drain position D is interposed between the bottom side of the second boom cylinder 5b and the pilot check valve 12. It is. The assist release valve 19 is urged toward the communication position C by a spring 20, and the pressure on the rod side of the first boom cylinder 5a is expanded to the urging force of the spring 20 as the piston pressure, thereby increasing the drain position. D
Side.

In the first aspect of the present invention, when the boom operating valve 8 is switched to the boom lowering position B and the boom 2 is lowered, pressure oil equivalent to that of the configuration shown in FIG. Is stored as potential energy. In the above operation in the downward excavation state, the first boom cylinder 5
When the pressure on the rod side of (a) becomes larger than the urging force of the spring 20, the assist release valve 19 is switched to the drain position D, and the bottom side of the second boom cylinder 5b is opened to the tank side. The resistance in the descending direction due to 5b is eliminated, the weight of the entire work machine is applied in the descending direction, and the working force due to this weight is added to the descending operation by the first boom cylinder 5a, and the digging utilizing the weight is performed. When the boom 2 rises , the configuration shown in FIG.
Just as, position energy stored in the accumulator 13 is assisted by acting on the second boom cylinder 5b. The configuration of the assist release valve 19 in this embodiment is shown in FIG.
As shown in FIG. 7, instead of the spring 20, an assist release valve 19a configured to bias the communication position C by the pilot pressure of the boom operation valve 8 may be used. By doing so, the assist release valve 19a can also function as the pilot check valve 12, and the circuit can be simplified.

The second invention shown in FIG. 5 is a further development of the first invention (FIGS. 3 and 4), wherein the bottom of the second boom cylinder 5b and the pilot check valve 12 are provided.
The function of a direction switching valve is added to the assist release valve 19b interposed between the first and second boom cylinders 5a, so that the pressure on the rod side of the first boom cylinder 5a becomes larger than the urging force of the spring 20, and the assist release valve 19b is moved to the drain position D. When the pressure is switched to the pressure, the hydraulic oil is supplied to the rod side of the second boom cylinder 5b, and the first and second two boom cylinders 5
The downward excavation operation of the boom 2 is performed by a and 5b.

The assist release valve 19b in the embodiment of the second invention is replaced with a spring 20 as shown in FIG.
The assist release valve 19c may be configured to switch to the communication position C side by the operation pilot pressure of the boom operation valve 8. In this case, the assist release valve 19c is the pilot check valve 1
2 works. FIG. 7 shows still another embodiment of the second embodiment of the present invention.
a, an assist release valve 19b that is switched by the pressure on the rod side and the pilot pressure for operating the boom operation valve 8 is provided.
When the pressure on the bottom side of the first boom cylinder 5a becomes equal to or higher than a predetermined value, a switching valve 21 is provided for communicating the rod sides of both boom cylinders 5a and 5b. The embodiment shown in this figure performs substantially the same operation as that shown in FIG.
5 and 6 showing the embodiment of the second invention, FIG.
2 is a suction safety valve. Note each of the assist release valves 19,19a in each of the embodiments described above, 19b, switching of 19c may be manually operated.

[0014]

According to the present invention, the first and the second using two lamps are provided.
The potential energy of the working machine can be recovered by one of the boom cylinders 5a and 5b of the boom cylinders 5a and 5b, so that it has been conventionally used in a standard-elevating working machine such as a backhoe. A cylinder dedicated to potential energy recovery is not required, so that the structure is simple and the cost can be reduced. Further, the assisting operation by recovering the potential energy can be canceled under a predetermined condition, and the potential energy of the working machine can be used as it is at the time of downward excavation of the working machine. Further, by switching the assist release valve, not only the raising operation but also the excavation operation of the working machine can be performed in all the lifting cylinders.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing an energy recovery apparatus to which the present invention is applied .

FIG. 2 is an explanatory view showing a different configuration of the boom direction switching valve shown in FIG . 1 ;

FIG. 3 is a schematic structural explanatory view showing the first invention.

FIG. 4 is a schematic configuration explanatory view showing a different configuration of the first invention.

FIG. 5 is a schematic structural explanatory view showing a second invention.

FIG. 6 is a schematic configuration explanatory view showing a different configuration of the second invention.

FIG. 7 is a schematic configuration explanatory view showing a different configuration of the second invention.

FIG. 8 is an explanatory diagram showing a problem of the device shown in FIG . 1 ;

FIG. 9 is a configuration explanatory view showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Revolving frame, 2 ... Boom, 3 ... Arm, 4 ... Bucket, 5a, 5b ... 1st and 2nd boom cylinder, 8 ...
Boom operation valve, 9: hydraulic pump, 10: check valve, 1
1 ... relief valve, 12 ... pilot check valve, 13 ...
Accumulator, 14 ... Pilot operated valve device, 15a, 15b
... Pilot circuit, 19, 19a, 19b, 19c ... Assist release valve, 20 ... Spring.

Claims (2)

(57) [Claims] 1. A bottom side and a rod side of at least one lifting cylinder of a plurality of lifting cylinders for lifting and lowering a working machine are connected to a hydraulic pump via a lifting operation valve, and at least another of the lifting cylinder is connected to the hydraulic pump. One lifting cylinder is used as an assist cylinder, and the bottom side of this assist cylinder is connected to a lifting operation valve via a check valve and to a pressure accumulator via a pilot check valve, respectively .
Connected to the tank side via a relief valve, the rod side to the tank, and the bottom side of the assist cylinder
Between the pilot check valve and
Drain position and drain position that communicates with the check valve side
A potential energy recovery device for a lifting and lowering work machine, comprising an assist release valve having a position. 2. The assist energy release device according to claim 1 , wherein the assist release valve supplies pressure oil from the pump to the rod side of the assist cylinder when the assist release valve is at the drain position. A potential energy recovery device for a lifting and lowering work machine, comprising: