JPS6239036Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a hydraulic jack.

As shown in FIG. 1, a conventional hydraulic jack sends hydraulic oil from an oil tank 1 to a ram lower chamber 3 by a hydraulic pump 2, and moves a ram 4 upward into a cylinder tube 5 according to the amount of oil. There are things that move the.

The hydraulic pump 2 sucks oil from the oil tank 1 through the suction passage 31 and the suction valve 32 as the plunger 30 rises, and pumps oil into the ram lower chamber 3 through the discharge valve 33 and the discharge passage 34 as the plunger 30 descends. Oil is pumped in to extend the ram 4.

In addition, 35 is a pressure relief valve provided in the bypass passage 36 that communicates the discharge passage 34 and the suction passage 31. By opening this pressure relief valve 35, the oil in the ram lower chamber 3 is returned to the oil tank 1 and the ram 4 is released. Lower it.

Incidentally, such a hydraulic jack is provided with a relief valve for excess oil in order to regulate the maximum pressure generated in the ram lower chamber 3 when the ram 4 reaches its maximum extension state. A lift limiting valve 6 is provided inside the ram 4 as this relief valve. This lift limiting valve 6 is normally pressed by a spring 7 to an opening 9 of a T-shaped through hole 8 communicating with the ram upper chamber 14 to maintain the pressure inside the ram lower chamber 3. A position detection pin 12 is inserted into the ram 4, and the push rod 10, which abuts orthogonally to the pin 12, abuts the lift limiting valve 6, and the pin 12 protrudes from the ram 4.
It extends to the vicinity of the inner wall of the cylinder tube 5.

When the ram 4 reaches its maximum extension, the position detection pin 1
The inner end of 2 contacts the lower surface 13 of the bearing part 37 and pushes down the push rod 10, which pushes down the lift limiting valve 6 against the spring 7 and opens the through hole 8.
is opened to allow excess oil sent from the piston 2 to escape into the ram lower chamber 14. Note that the ram upper chamber 14 communicates with the oil tank 1 via a through hole 38.

However, with this head limiting mechanism,
Since the ram 4 has many holes to be drilled and has a large number of parts, not only is it disadvantageous in terms of cost, but when the ram is alone, the pin 12 does not have a stop and can be lost.
You may forget to assemble it.

Therefore, the present invention eliminates the lifting height limiting mechanism inside the ram, and installs a float valve inside the oil tank that determines the ram's maximum extension state from the oil level in the oil tank and stops the suction of oil from the oil tank to the hydraulic pump. The purpose is to simplify the lift limiting mechanism.

Embodiments of the present invention will be described below based on the accompanying drawings. Note that the same reference numerals are given to the same components as in the conventional example.

As shown in FIGS. 2 and 3, a mortar-shaped sheet 16 is formed at the opening of the suction passage 15 that opens at the bottom of the oil tank 1. As shown in FIGS. In addition, there is a suction passage 15 inside the oil tank 1 when seated on this seat 16.
A spherical float valve 17 having a size to close the float valve 17 is provided, and a dome-shaped wire mesh 18 is attached to the upper part of the seat 16 so as to cover the float valve 17.

The float valve 17 is made of a material having a specific gravity smaller than that of oil, such as rubber or resin.

By the way, a predetermined amount of oil is filled inside the oil tank 1 so that the liquid level will drop until the float valve 18 is closed when the ram 4 is fully extended. In this embodiment, a hole 25 for regulating the maximum height of the liquid level is formed on the side surface of the oil tank 1, and the hole 25 is sealed with a rubber stopper 20 after being filled with hydraulic oil.

Next, the effect will be explained.

At the beginning of the stroke of the ram 4, when the amount of oil sent into the ram lower chamber 3 by the hydraulic pump 2 is small, the liquid level in the oil tank 1 is high and the float valve 17 separates from the seat 16 due to its buoyancy and comes into contact with the top surface of the wire mesh 18. The suction passage 15 is opened.

However, when the ram 4 reaches its maximum extension and the liquid level in the oil tank approaches the bottom surface 19, the float valve 17
approaches the seat 16 and finally sits on the seat 16, blocking the suction passage 15.

Therefore, even if an attempt is made to raise the plunger 30 of the hydraulic pump 2, the hydraulic oil is not sucked in, and the supply of excess oil is stopped.

As another embodiment of the float valve 17, as shown in FIG.
and an insertion part 23 inserted into the through hole 15, and a float 21 is connected to the upper part of the insertion part 23 to increase buoyancy. A case 24 is provided around the seat 16 to limit the floating position of the float 21 so that the float valve 17 is normally separated from the seat 16 by an appropriate distance.

As described above, the present invention detects the drop in the liquid level in the oil tank when the ram reaches its maximum extension, and
Since a float valve is provided to close the suction passage, the lift limiting mechanism of the hydraulic jack can be significantly simplified compared to the conventional lift limiting mechanism inside the ram, which greatly contributes to cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional hydraulic jack. FIG. 2 is a side sectional view of a hydraulic jack that is an embodiment of the present invention. FIG. 3 is an enlarged view of the area around the float valve. FIG. 4 is an enlarged view of the surroundings of a float valve of another embodiment. 1... Oil tank, 2... Hydraulic pump, 4... Hydraulic ram, 15... Suction passage, 17... Float valve.

Claims (1)

[Scope of utility model registration request] In a hydraulic jack that sends hydraulic oil from an oil tank to a hydraulic ram via a hydraulic pump,
An opening connected to the suction passage of the hydraulic pump is provided at the bottom of the oil tank, and a float valve is installed in this opening to sense the oil level and close the valve when the oil level drops. A hydraulic jack characterized by enclosing.