JPS622001A - Hydraulic unit - Google Patents

Abstract

PURPOSE:To reduce the maximum width of a hydraulic unit by installing a hydraulic pump and a motor inside the inner cylinder of an accumulator. CONSTITUTION:An inner cylinder is coaxially provided inside an outer cylinder 1, and a piston 4 which divides a space between the outer cylinder 1 and the inner cylinder, into an air chamber 5 and an oil chamber 6, is slidably provided in the space. And, a spring 7a which applies a compression force to the piston 4, is provided in the air chamber 5, while a hydraulic pump 11 and a motor 12 are provided inside the inner cylinder. Thereby, the maximum width D of a hydraulic unit can be made shorter, reducing the diameter of the housing place of the hydraulic unit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic unit that supplies high-pressure hydraulic oil to hydraulic equipment such as a hydraulic actuator.

Conventional technology A conventional hydraulic unit is, for example, disclosed in U.S. Pat.
As shown in the publication, the structure was as shown in FIGS. 3 and 4. That is, inside a block 17 forming a passage 16 that communicates the suction boat 14 with the discharge port 15 and each of these ports (the hydraulic oil flowing from the suction boat 14 is pressurized, and the hydraulic oil flows through the passage 16 into the discharge port 15). A hydraulic pump 18 to be supplied is housed, and a motor 19 for driving the hydraulic pump 18 is disposed in the block 17 to form a hydraulic circuit, and a safety valve 2o is activated when the hydraulic pressure of the hydraulic circuit exceeds a predetermined pressure. The structure is such that an accumulator 21 for storing pressure oil in the hydraulic circuit is connected to a predetermined location of the passage 16 and is fixed to the block 17.Problems to be Solved by the InventionHowever, the problem with such a structure is that it is fixed to the block 17. In the hydraulic unit, motor 1
9 and the accumulator 21 are arranged side by side, the maximum width of the hydraulic unit (W in FIG. 2) cannot be made shorter than the sum of the width of the motor 19 and the width of the accumulator 210. Therefore, for example, when a hydraulic unit as a drive source of an industrial robot driven by hydraulic pressure is housed inside the arm of the industrial robot, there is a problem in that the diameter of the storage space becomes large.

In view of the above-mentioned problems, the present invention shortens the maximum width of the hydraulic unit, and makes it possible to reduce the storage space, for example, when storing the hydraulic unit as the drive source of an industrial robot driven by hydraulic pressure inside the arm of the industrial robot. This allows the diameter to be reduced.

Means for Solving the Problems In order to solve the problems of the conventional hydraulic unit described above, the present invention provides an outer cylinder, an inner cylinder located coaxially inside the outer cylinder, two cylinder ends, a ring-shaped piston that is slidably disposed in a space surrounded by the outer cylinder, the inner cylinder, and the two cylinder ends and separates the space into an oil chamber and an air chamber; and a ring-shaped piston that is disposed in the air chamber and has the ring shape. an accumulator comprising at least one spring that applies a compressive force to the piston; a port that supplies and discharges oil to and from the oil chamber; and a suction port that is arranged coaxially with the accumulator inside the inner cylinder of the accumulator. a hydraulic pump that pressurizes hydraulic oil flowing in from the accumulator and discharges it into an oil passage communicating with the port of the accumulator; a motor that is disposed coaxially with the accumulator inside the inner cylinder of the accumulator and drives the hydraulic pump; The present invention provides a hydraulic unit including a safety valve that operates when the hydraulic pressure of hydraulic oil discharged from the hydraulic pump into the oil passage exceeds a predetermined pressure.

As described above, the present invention can shorten the maximum width of the hydraulic unit by arranging the hydraulic pump and motor inside the inner cylinder of the accumulator. When storing a hydraulic unit as a drive source inside the arm of an industrial robot, the storage space can be made smaller in diameter.

Embodiments Below, embodiments of the present invention will be explained based on FIGS. 1 and 2. FIG. 1 is a sectional view showing the specific structure of a hydraulic unit in a first embodiment of the present invention.

In FIG. 1, 1 is an outer cylinder, 2 is an inner cylinder located coaxially inside the outer cylinder 1, 3a and 3b are cylinder ends, and the outer cylinder 1, the inner cylinder 2, and the two Cylinder end 3a.

A ring-shaped piston 4 is slidably disposed in a hollow cylindrical space surrounded by 3b, and divides the hollow cylindrical space into an air chamber 5 and an oil chamber 6. A spring 7a has both ends in contact with the cylinder end 3a and the ring-shaped piston 4, and applies a compressive force to the ring-shaped piston 4. 8 is a port for supplying and discharging oil to the oil chamber 6, and communicates with a hydraulic pump 11 coaxially arranged inside the inner cylinder 2 via an oil passage 10 formed inside the cylinder end 3b. are doing. The hydraulic pump 11 is driven by a motor 12 coaxially arranged inside the inner cylinder 2 via a joint.

In FIG. 1, when the motor 12 is operated and the hydraulic pump 11 is rotated, the hydraulic pump 11 sucks hydraulic oil from the suction port 9, compresses it, and discharges high-pressure hydraulic oil into the oil passage 1o. .

The high-pressure hydraulic oil discharged into the oil passage 1o flows into the oil chamber 6 through the port 8, pushes up the ring-shaped piston 4, and compresses the spring 7a arranged in the air chamber 5. . Then, the ring-shaped piston 4 moves to a position where the compressive force of the spring 7a disposed in the air chamber 6 and the total pressure of the high-pressure hydraulic oil inside the oil chamber 6 pushing up the ring-shaped piston are balanced. do.

A safety valve 13 is activated when the pressure in the oil passage 1o exceeds a predetermined pressure, and by communicating the oil passage 10 with a passage leading to the low-pressure suction port 9, the pressure inside the oil passage 10 is maintained at a predetermined level. This prevents the pressure from exceeding the limit and prevents damage to the equipment due to high pressure. When the pressure inside the oil passage 1o decreases due to load fluctuations in the hydraulic equipment connected to the port 8, the high-pressure hydraulic oil inside the oil chamber 6 pushes up the ring-shaped piston at full pressure. is lower than the compressive force of the spring 7a disposed in the air chamber 5, the ring-shaped piston 4 is pushed down, and the hydraulic oil in the oil chamber 6 is discharged from the port 8, causing the hydraulic equipment to Supplied.

FIG. 2 is a sectional view showing a specific configuration of a hydraulic unit in a second embodiment of the present invention. In the specific configuration of the hydraulic unit in the second embodiment shown in FIG.
The difference from the specific configuration of the hydraulic unit in the first embodiment shown in the figure is that in the first embodiment, one large diameter spring was disposed inside the air chamber. On the other hand, inside the air chamber 5, a plurality of small diameter springs 7b are arranged in an annular manner.

The operation of the hydraulic unit in the second embodiment shown in FIG. 2 is similar to the operation of the hydraulic unit in the first embodiment shown in FIG. Whether or not to use a plurality of small diameter springs arranged in an annular shape can be determined by considering hydraulic pressure, material properties of the springs, etc.

Effects of the Invention Through the above-described effects, the present invention prevents instantaneous flow shortages and pressure drops due to insufficient capacity of the hydraulic pump, prevents deterioration of responsiveness, absorbs pulsation of the hydraulic pump, and reduces pressure. Fluctuations can be smoothed out.

In addition, by arranging the hydraulic pump and motor inside the inner cylinder of the accumulator, the maximum width of the hydraulic unit (D in Figures 1 and 2) can be shortened. When a hydraulic unit serving as a drive source for an industrial robot is housed inside the arm of an industrial robot, the diameter of the storage space can be reduced, which has a great practical effect.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a hydraulic unit in a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the configuration of a hydraulic unit in a second embodiment of the present invention, and FIG. FIG. 4 is a sectional view showing the configuration of the existing hydraulic unit. FIG. 4 is a sectional view taken along line XX in FIG. 1...Outer cylinder, 2...Inner cylinder, 3a. 3b... Cylinder end, 4... Ring-shaped piston, 5... Air chamber, 6 River... Oil chamber, 7... Spring, 8 ...port, 9...
... Suction boat, 10. River... Oil passage, 11...
...Hydraulic pump, 12...Motor, 13...
····safety valve. Name of agent: Patent attorney Toshio Nakao (1 person f--)
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Claims (1)

[Claims] an outer cylinder, an inner cylinder located coaxially inside the outer cylinder, two cylinder ends, and a space surrounded by the outer cylinder, the inner cylinder, and the two cylinder ends, and is slidably disposed in a space surrounded by the outer cylinder, the inner cylinder, and the two cylinder ends. a ring-shaped piston that separates the space into an oil chamber and an air chamber; at least one spring that is disposed inside the air chamber and applies a compressive force to the ring-shaped piston; and supply and discharge oil to and from the oil chamber. a hydraulic pump that is arranged coaxially with the accumulator inside the inner cylinder of the accumulator and pressurizes hydraulic oil flowing in from the suction port and discharges it into an oil passage communicating with the port of the accumulator. and a motor that is disposed coaxially with the accumulator inside the inner cylinder of the accumulator and drives the hydraulic pump, and when the hydraulic pressure of hydraulic oil discharged from the hydraulic pump into the oil passage exceeds a predetermined pressure. Hydraulic unit consisting of a safety valve that operates.