JPS6272901A - Hydraulic power unit - Google Patents

Abstract

PURPOSE:To compact a hydraulic unit by arranging a hydraulic pump and motor at the internal cylinder side of an accumulator and also by constituting an oil tank in a body. CONSTITUTION:The hollow cylindrical space enclosed by an external cylinder 1, internal cylinder 2, and end plates 3a and 3b is divided into 2 parts by a projecting section 2a. A piston 4 is arranged there at liberty to be slidden dividing it into a gas chamber 5 and an oil chamber 6. A bulkhead 15 is arranged in the upper side space of the hollow cylindrical space at liberty to be slidden dividing the upper side space into an oil tank 16 and an air chamber 17. The maximum width of a hydraulic unit can, thus, be shorten and the constitution members of a motor cover or the like can be reduced and compacted.

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. 2 and 3. That is, a suction port 21 that sucks oil from a separately arranged oil tank (not shown).
The suction port 21 is located in a block 24 that has a discharge port 22 and a passage 23 that communicates these ports.
A hydraulic pump 25 that pressurizes the hydraulic fluid flowing in from the block and supplies it to the discharge port 22 through the passage 23 is housed, and a motor 26 for driving the hydraulic pump 26 is disposed in the block 24 to form a hydraulic circuit. a safety valve 27 which is formed and operates when the hydraulic pressure of the hydraulic circuit exceeds a predetermined pressure;
It stores the pressure oil in the hydraulic circuit, compensates for momentary flow shortages and pressure drops due to insufficient capacity of the hydraulic pump, prevents deterioration of responsiveness, absorbs pulsation of the hydraulic pump, and smoothes pressure fluctuations. an accumulator 28 which is
It has a structure in which it is connected to a predetermined location of 3 and fixed to the plot 24.

Problems to be Solved by the Invention However, in a hydraulic unit having such a structure, the motor 2
Since θ and accumulator 2B are arranged side by side, there is a limit to weight reduction, and the maximum width of the hydraulic unit (second
W) in the figure cannot be made shorter than the sum of the width of the motor 26 and the width of the accumulator 28. Therefore, for example, when storing a hydraulic unit as a drive source of a hydraulically driven industrial robot inside the arm of the industrial robot, there is a problem that the weight of the arm increases and the diameter of the storage space increases. In addition, since the hydraulic pump 26 and motor 26 are exposed, there is a problem in that the noise is large. Furthermore, since the oil tank needs to be placed separately, hydraulic piping is required to connect the hydraulic unit and the oil tank, which poses a problem in that the configuration is complicated and it is difficult to downsize.

In view of the above-mentioned problems, the present invention aims to reduce the maximum width of the hydraulic unit and to miniaturize the configuration by integrating the oil tank.For example, the hydraulic unit can be used as a drive source for an industrial robot driven by hydraulic pressure. When storing the robot inside the arm of an industrial robot, the weight of the arm can be reduced, the diameter of the storage space can be reduced, and noise can be reduced.

Means for Solving the Problems In order to solve the problems of the conventional hydraulic unit, the present invention arranges an outer cylinder and an inner cylinder that constitute an accumulator substantially coaxially, and connects the outer cylinder and the inner cylinder with each other. In the space defined by the cylinder end plate, a ring-shaped piston is arranged to be slidable in order to separate the space into an oil chamber and a gas chamber, and the piston intervenes in the supply of gas to the gas chamber. It includes a valve and a boat for supplying and discharging oil to and from the oil chamber, and inside the inner cylinder, a hydraulic pump and a motor for driving the hydraulic pump are disposed approximately coaxially with the inner cylinder, and a volumetric It is equipped with an oil tank that has variable oil pressure.

Function As described above, the present invention disposes a hydraulic pump and a motor inside the inner cylinder of an accumulator, and
By integrating the oil tank, the maximum width of the hydraulic unit can be shortened, the number of component parts such as the motor cover can be reduced, and the weight can be reduced due to the miniaturization of the component parts.At the same time, the noise from the hydraulic pump and motor can be reduced directly. Since it is not emitted into the atmosphere, for example, when storing a hydraulic unit inside the arm of an industrial robot as a drive source for a hydraulically driven industrial robot, it is possible to reduce the weight of the arm and make the storage location more compact. , and the sound can be lowered.

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 is a front sectional view showing the specific structure of a hydraulic unit according to an embodiment of the present invention.

In FIG. 1, 1 is an outer cylinder, 2 is an inner cylinder located approximately coaxially inside the outer cylinder 1, 3a and 3b are cylinder end plates, and the outer cylinder 1, the inner cylinder 2, and the two A hollow cylindrical space surrounded by the cylinder end plates 3a and 3b is divided into two by a protrusion 2a formed on the inner cylinder 2. A ring-shaped piston 4 is slidably disposed in the lower space of the hollow cylindrical space divided into two, and divides the lower space into a gas chamber 5 and an oil chamber 6. . The pressure inside the gas chamber 5 is set to a predetermined pressure by supplying gas through the valve 7. 8 is a boat that supplies oil to the oil chamber 6, and an oil passage 1 formed inside the cylinder end plate 3b.
It communicates with a hydraulic pump 11 that is arranged substantially coaxially inside the inner cylinder 2 through the inner cylinder 2. Said hydraulic pump 1
1 is driven by a motor 12 disposed substantially coaxially inside the inner cylinder 2 via a joint 14.

A ring-shaped partition wall 16 is slidably disposed in the upper space of the hollow cylindrical space divided into two, and divides the upper space into an oil tank 16 and an atmospheric chamber 17. A spring 18 is disposed inside the atmospheric chamber 17 and presses the partition wall 15 downward.

In FIG. 1, when the motor 12 is operated and the hydraulic pump 11 is rotated, the hydraulic pump 11 sucks hydraulic oil through the suction port 9 communicating with the oil tank 16 and compresses it to high pressure. of hydraulic oil is discharged into the oil passage 10. The high-pressure hydraulic oil discharged into the oil passage 1° flows into the oil chamber 6 through the boat 8, pushes up the ring-shaped piston 4, and compresses the gas filled in the gas chamber 6. At this time, the partition wall 15 is pushed down as the hydraulic oil inside the oil tank 16 decreases. The ring-shaped piston 4 then moves to a position where the pressure in the gas chamber 6 and the pressure in the oil chamber 6 are balanced. 1
Reference numeral 3 denotes a safety valve, which is activated when the pressure in the oil passage 10 exceeds a predetermined pressure, and connects the oil passage 10 with the passage leading to the low-pressure suction boat 9.
This prevents the internal pressure from exceeding a predetermined pressure and prevents the device from being destroyed by high pressure. Here, due to load fluctuations of the hydraulic equipment connected to the pressure boat 19, etc.
When the pressure inside the oil passage 10 decreases, the pressure inside the oil chamber 6 becomes lower than the pressure inside the gas chamber 5, so the ring-shaped piston 4 is pushed down, and the hydraulic oil inside the oil chamber 6 is reduced. It is discharged from the pressure boat 19 and supplied to hydraulic equipment. On the other hand, the hydraulic oil discharged from the hydraulic equipment returns to the oil tank 16 via a return port 20. At this time, the partition wall 16 is pushed up by the increase in the hydraulic oil inside the oil tank 16. As described above, in the present invention, since the inside of the oil tank is always filled with oil, the structure is such that even if the attitude of the hydraulic unit changes, the hydraulic pump does not inhale atmospheric air.

In this embodiment, an oil tank is formed in a space surrounded by an outer cylinder, an inner cylinder, and a cylinder end plate, and a partition wall and a spring are used as means for varying the volume of the oil tank. However, it is not necessary to provide the oil tank at the above location. It goes without saying that the means to change the volume of an oil tank does not necessarily have to be a bulkhead and a spring; for example, it is also possible to make the oil tank out of an elastic material such as rubber.

Effects of the Invention As described above, by arranging the hydraulic pump and motor on the side of the inner cylinder of the achimulator and integrating the oil tank, the maximum width of the hydraulic unit (D in Figure 1) can be shortened. At the same time, it is possible to reduce the number of component parts such as the motor cover, and to reduce the weight due to the miniaturization of the component parts.
Since the noise from the hydraulic pump and motor is not emitted directly into the atmosphere, it is possible to reduce the weight of the arm, for example when storing the hydraulic unit as the drive source of a hydraulically driven industrial robot inside the arm of the industrial robot. This makes it possible to reduce the size of the storage area, reduce the diameter of the storage space, and reduce noise, and the practical effects of this are significant.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing the configuration of a hydraulic unit according to an embodiment of the present invention, FIG. 2 is a front sectional view showing the configuration of a conventional hydraulic unit, and FIG. 3 is a line xx in FIG. 2.
FIG. 1...Outer cylinder, 2...Inner cylinder, 3a. 3b...Cylinder end plate, 4...Ring-shaped piston, 5...Gas chamber, 6...
・Oil chamber, 7...Valve, 8...Boat, 1
1...Hydraulic pump, 12...Motor, 1
6...Oil tank. Name of agent: Patent attorney Toshio Nakao and one other person Yu7iJ,. Z7゜1'-[-gef&-one oil perilla Fig. 2 Fig. 3

Claims (1)

[Claims] an outer cylinder, an inner cylinder located substantially coaxially inside the outer cylinder, two cylinder end plates, and a space surrounded by the outer cylinder, the inner cylinder, and the two cylinder end plates so as to be slidable therein; An accumulator is constituted by a ring-shaped piston arranged to separate the space into an oil chamber and a gas chamber, a valve intervening for supplying gas to the gas chamber, and a port for supplying and discharging oil to the oil chamber, A hydraulic pump that pressurizes hydraulic oil and supplies it to the oil chamber is provided inside the inner cylinder substantially coaxially with the accumulator, and a motor that drives the hydraulic pump is provided, and an oil tank having a variable volume is provided. Hydraulic unit.