JPS6246867Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a hydraulic drive device for high water content hydraulic fluid (so-called
power unit).

This type of hydraulic drive device uses a hydraulic fluid containing a large amount of water, that is, a high water content hydraulic fluid, instead of a petroleum-based hydraulic fluid, so it is used on the suction side of the pump, which is one of its main components. cavitation is likely to occur, which may shorten the life of the pump. In order to prevent this, generally a tank containing a highly water-containing hydraulic fluid is disposed above the pump to apply positive pressure to the suction side of the pump.

By the way, conventionally, in this type of hydraulic drive device, as shown in FIG. A suction pipe 13 to connect and a pump drain pipe 14 to connect the drain port 11b of the pump 11 and the inside of the tank 12 are respectively led out from the side or bottom of the tank 12 and are piped.
For maintenance (repair), both pipes 13 and 14 are provided with stop valves 15 and 16, respectively, and the suction pipe 13 is provided with an expensive suction filter 17 with a case. For this reason, the cost of the hydraulic drive device is high. Note that this hydraulic drive device drives the machine with high water content hydraulic fluid that is supplied to a machine (not shown) from the discharge port 11c of the pump 11 and is returned to the tank 12.

The present invention has been made to reduce the cost of the hydraulic drive device, and one embodiment thereof will be described below with reference to the drawings. FIG. 2 shows a hydraulic drive device in which the present invention is implemented, and in this hydraulic drive device, a motor 20 is installed in a unit base B.
A pump 21 is attached to the unit stand B, and a tank 22 containing a highly water-containing hydraulic fluid is attached above the unit stand B. Further, the suction port 21a of the pump 21 and the inside of the tank 22 are connected through a suction pipe 23, and the drain port 21b of the pump 21 and the inside of the tank 22 are connected through a pump drain pipe 24. In addition, in this hydraulic drive device,
The machine tool is driven by the highly water-containing hydraulic fluid that is supplied from the discharge port 21c of the pump 21 to a machine tool (not shown) and flows back into the tank 22.

In this embodiment, a portion 23a of the suction pipe 23 is removably fixed to the suction lid 25 (cover 22a of the tank 22, and covers the opening _22a1 provided in the cover 22a).
The pump drain pipe 24 is located above the liquid level L in the tank 22 to form a siphon.
It penetrates through a and is located above the liquid level L in the tank 22, forming a siphon. Also, each pipe 23, 24 located above the liquid level L in the tank 22
Ports 23a and 24a are provided with ports 23 that can communicate with the atmosphere, as shown in FIGS. 2 and 3.
a ₁ , 24a ₁ are provided, each port 23a ₁ , 24a ₁
Plugs 26 and 27 are removably attached to each of them. Each plug 26, 27 is screwed into each port 23a ₁ , 24a ₁ , and each plug 26, 27 is screwed into each port 23a ₁ , 24a 1.
4a ₁ is closed and each port 23 is closed when removed.
Release (open) a ₁ , 24a ₁ and connect each port 23
a ₁ and 24a ₁ are communicated with the atmosphere. Further, in this embodiment, an inexpensive strainer 28 is attached to the tank inner end 23b of the suction pipe 23. This strainer 28 is configured so that it can be taken out from the tank 22 through an opening 22a ₁ provided in the cover 22a of the tank 22. For this purpose, the suction pipe 23 is provided with a pipe joint 23c, and the suction lid 25 is removably fixed to the cover 22a.

In this embodiment configured in this way, when the pump 21 is driven by the motor 20 with the ports 23a ₁ and 24a ₁ closed by the plugs 26 and 27, the pump 21 is initially in suction mode. The air in the pipe 23 is temporarily sucked in, but after that, positive pressure acts on the suction side of the pump 21 due to the siphon principle, suppressing the occurrence of cavitation. By the way, when repairing the pump 21, if each plug 26, 27 is removed from each port 23a ₁ , 24a ₁ and each port 23a ₁ , 24a ₁ is communicated with the atmosphere, air will enter from each port 23a ₁ , 24a ₁ . Since the highly water-containing working fluid from each port 23a ₁ , 24a ₁ to the liquid level L returns to the tank 22, in this state, the suction port 21a of the pump 21 and the suction pipe 23 are disconnected and the drain port 21
If the connection between the pump drain pipe 24 and the pump drain pipe 24 is removed, only the highly water-containing hydraulic fluid remaining in the pipes 23 and 24 will leak, but the hydraulic fluid in the tank 22 will not flow out, and the pump 21 can be repaired.

In summary, in the present invention, as exemplified in the above embodiment, parts 23a and 24a of both pipes 23 and 24 are connected to the liquid level L in the tank 22, respectively.
A part 23a of both pipes 23 and 24 is positioned higher to form a siphon.
24a each have a port 23a ₁ communicating with the atmosphere,
24a ₁ is provided, and these ports 23a ₁ and 24a ₁ can be opened and closed by plugs 26 and 27, respectively, so maintenance of the pump can be performed without installing a stop valve in the suction pipe and pump drain pipe as in the past. Therefore, it is possible to reduce the cost of the hydraulic drive device.

In addition, when implementing the present invention, as illustrated in the above embodiment, the suction pipe 23 is disposed to pass through the suction lid 25, and the strainer 28 is attached to the tank inner end 23b of the suction pipe 23. If implemented, the cost of the hydraulic drive device can be further reduced. In addition, when implementing the present invention, as shown in FIG.
Parts 33a and 34a of the suction pipe 33 and the pump drain pipe 34 led out from the sides of the tank 32 are respectively positioned above the liquid level L to form a siphon, and one part of both pipes 33 and 34 is positioned above the liquid level L in the tank 32. Ports 33a _{1 and 34a 1 communicating with the atmosphere are provided in the portions 33a and 34a, respectively, and these ports 33a 1 and 34a 1 are connected to} the plug 3, respectively.
It is also possible to make it possible to open and close it by means of 6 and 37. In this case, for convenience of maintenance, it is desirable to employ a suction filter 38 with a case.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional hydraulic drive device for high water content hydraulic fluid, FIG. 2 is a block diagram of a hydraulic drive device for high water content hydraulic fluid that implements the present invention, and FIG. FIG. 4 is a block diagram of a hydraulic drive device for high water content hydraulic fluid showing another embodiment of the present invention. Explanation of symbols, 21...Pump, 21a...Suction port, 21b...Drain port, 21c...Discharge port, 22...Tank, 23...Suction pipe, 23a...Part of suction pipe, 2
3a ₁ ...Port, 24...Pump drain pipe,
24a... Part of the pump drain pipe, 24a ₁ ...
...Port, 26, 27...Plug, L...Liquid level in the tank.

Claims (1)

[Scope of utility model registration request] A tank containing a highly water-containing working fluid is disposed above the pump, and the suction port of the pump and the inside of the tank are connected by a suction pipe, and the drain port of the pump and the inside of the tank are connected to each other. In the hydraulic drive device for high water content hydraulic fluid, the machine is driven by high water content hydraulic fluid that is connected by a drain pipe and is supplied to the machine from the discharge port of the pump and returns to the tank. Parts of the pipes are located above the liquid level in the tank to form a siphon, and ports communicating with the atmosphere are provided in the parts of the pipes located above the liquid level in the tank, respectively, A hydraulic drive device for high water content hydraulic fluid that allows each of these ports to be opened and closed using plugs.