JPS6119975Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a hydraulic jack used in hand pallet lifts and other lifting devices for handling cargo.

This type of hydraulic jack, which has been commonly used in the past, has a suction oil passage that communicates between the oil tank and the manual plunger pump via a suction valve, a discharge oil passage that communicates the pump and the ram cylinder via a discharge valve, and a return oil passage that communicates the discharge oil passage with the oil tank via a lift/lower switching valve, and is configured to forcefully send oil in the oil tank into the ram cylinder with a pump to raise the ram of the ram cylinder. The ram is raised or lowered using a switching valve. However, since the above-mentioned switching valve does not have a neutral position, when transporting cargo while holding it at a predetermined height, pushing or pulling force is applied to the pump's operating handle, causing the pump to move the load inside the ram cylinder. The disadvantage was that the ram would rise as the oil was supplied, making it difficult to hold the ram or load in place.

For this reason, the oil tank and the pump cylinder are communicated via a suction oil passage via a suction valve, and the ram cylinder and oil tank are communicated via a switching oil passage via a switching valve that can be switched to a raised position, a neutral position, and a lowered position. In addition, a hydraulic jack has been proposed in which a pump cylinder and a switching valve are communicated via a discharge oil passage via a discharge valve (see Japanese Patent Publication No. 34824/1983). However, in such conventional hydraulic jacks, a switching valve is provided in a curved oil passage, and the switching valve has a large number of spheres, so
The configuration of the switching valve and the oil passage therefor is complicated, and therefore the configuration of the entire hydraulic jack is also complicated.

The purpose of this invention is to provide a hydraulic jack that can switch the ram in three stages: ascending, neutral, and descending, and has an extremely simple structure.

The hydraulic jack according to this invention is the hydraulic jack as described above, in which the switching oil passage includes a linear stepped oil passage including the switching valve chamber, an oil passage communicating between one end of the switching valve chamber and the ram cylinder, and It consists of a return oil passage that communicates the other end of the switching valve chamber with the oil tank, and one end of the discharge oil passage is connected to the middle part of the switching valve chamber, and the oil return passage is connected to the oil passage side of the ram cylinder from the discharge oil passage. At the closer part, the part of the switching valve chamber on the oil passage side becomes thicker, and a stepped first valve seat is provided in this part. The part of the chamber on the oil return passage side is tapered and a stepped second valve seat is provided in this part, and the switching valve is connected between the first valve seat in the switching valve chamber and the oil passage of the ram cylinder. A large-diameter spherical valve body is provided between the valve seats to open and close the valve seat, and a second valve body in the switching valve chamber
A small diameter ball valve is installed between the valve seat and the discharge oil passage to open and close the valve seat, and a large diameter ball valve is fixedly inserted into the stepped oil passage from the end on the large diameter ball valve side. A valve stem that limits the amount of movement of the valve body in the opening direction away from the first valve seat, and compression that presses the large diameter spherical valve body attached to the valve stem against the first valve seat and biases it in the closing direction. Equipped with a coil spring and a valve switching rod movably inserted into the stepped oil passage from the end on the small diameter ball valve body side, the valve switching rod is in a raised position where it does not touch the small diameter ball valve body, only the small diameter ball valve body The valve can be switched to a neutral position in which only the second valve seat is forcibly opened by pressing the valve, and a lowered position in which both valve seats are forcibly opened by pushing the large-diameter spherical valve element together with the small-diameter spherical valve element. It is something that

In other words, the feature of this invention is that the switching valve is composed of a large-diameter spherical valve body, a small-diameter spherical valve body, a valve stem, a coil spring, and a valve switching rod, and these are arranged in a linear oil passage. It is in.

An embodiment in which this invention is applied to a hand pallet lift will now be described with reference to the drawings.

In the figure, 1 is a fork, 2 is a fork support frame, 3 is a front wheel, 4 is a reversible rear wheel, and 5 is a rear wheel 4
A ram cylinder is rotatably attached to the center of the upper reversing chassis 6 and has its lower end fixed to the axle 4A of the rear wheel 4, and is constructed at the lower part of the hydraulic jack body 7. Reference numeral 8 denotes an oil tank, and a ram 9, which has a larger diameter than the diameter of the ram cylinder 5 and is fitted in the working chamber 5A of the ram cylinder 5 in the upper part following the ram cylinder 5 so as to be movable up and down, is an upper cover of the oil tank 8. 1
0 through the ram through hole 11 at the center of the upper end.
A fork support frame 2 is placed on the upper end of this ram 9.

Reference numeral 12 designates a connecting link having one end pivotally connected to both end surfaces of the reversing chassis 6 and the other end pivotally connected to the fork support frame 2; 13 a plunger pump; It is located at the rear of the tank 8 and is erected with an axis parallel to the ram cylinder 5. Reference numeral 15 denotes a redirecting/pump operation handle, and 16 a handle support arm. The handle 15 is pivotally attached to the upper end of the handle support arm 16 by a pin 18 via a yoke-shaped attachment member 17. A roller 19 pivotally mounted diagonally above the pin 18 of the operating handle 15 is brought into contact with the head of the plunger 20 of the pump cylinder 14, and by swinging the operating handle 15 back and forth, the plunger 20 is rotated. 20 is raised and lowered.

21 is a hydraulic jack switching operation lever attached to the upper part of the operation handle 15;
The operating rod 22 is pivotally connected to the upper end of the operating rod 22 inserted into the tube body 15A. In addition, this operating rod 22
The lower end of the L-shaped lever 23 is connected to one end of the L-shaped lever 23 which is pivotally attached to the side of the yoke-shaped mounting member 17.
The other end of the shaped lever 23 is connected to the upper end of a valve switching rod actuating lever 24 pivotably mounted on the side surface of the support arm 16.

A plunger 20 fitted into the pump cylinder 14 so as to be able to rise and fall is constantly pushed up by a compression coil spring 27 fitted into an inner cavity 25 of a casing 26 formed concentrically outside the pump cylinder 14. It penetrates and is fixed to the casing cover 28.

A suction oil passage 29 communicates the oil tank 8 and the pump cylinder 14, and a suction valve 30 is interposed therein. 41 is a linear stepped oil passage that includes the switching valve chamber 32A and the switching valve 32 is provided therein, 34 is an oil passage that communicates one end of the switching valve chamber 32A with the ram cylinder 5, and 44 is a switching valve. Room 32A
This is a return oil passage that communicates the other end with the oil tank 8, and these oil passages 34, 41, and 44 constitute a switching oil passage that communicates the ram cylinder 5 and the oil tank 8. 31 is the pump cylinder 14
A discharge oil passage that communicates between the switching valve chamber 32A and the middle of the switching valve chamber 32A, and a discharge valve 33 is interposed therein.

The switching valve chamber 32A is slightly connected to the oil passage 34 of the ram cylinder 5 from the switching valve chamber side opening 31A of the discharge oil passage 31.
The oil passage 34 side is thicker in the part closer to the side, and a stepped first valve seat 36 and a large diameter spherical valve body 35 for opening and closing the valve seat are provided in this part.
Further, the switching valve chamber 32A is tapered on the oil return passage 44 side at a portion slightly closer to the oil return passage 44 side of the oil tank 8 from the opening 31A, and a stepped second valve seat 38 and a stepped second valve seat 38 are formed in this portion. , and a small diameter ball valve body 37 that opens and closes this. A fixed valve shaft 39 is inserted into a portion of the stepped oil passage 41 outside the large-diameter spherical valve body 35 to limit the amount of movement of the large-diameter spherical valve body 35 in the opening direction away from the first valve seat 36. A compression coil spring 40 is interposed between the valve shaft 39 and the large-diameter spherical valve element 35 to press the large-diameter spherical valve element 35 against the valve seat 36 and bias it in a direction to close it. In addition, in the portion of the stepped oil passage 41 outside the small diameter ball valve body 37,
A valve switching rod 42 is movably inserted through a compression coil spring 43, and the valve switching rod 42 is always urged outward by the spring 43. The outer end 42A of the valve switching rod 42 is formed into a hemispherical shape and is brought into contact with the lower end of the operating lever 24. By operating the operating lever 21 of the operating handle 15, the operating lever 24 is swung via the operating rod 22 and the L-shaped lever 23, and as a result, the valve switching rod 42 is moved to the raised position of the ram 9 and to the neutral position. It can be switched to three stages: position and lowered position. When the valve switching rod 42 is at the outermost raised position as shown in FIG. The two ball valve bodies 35 and 37 can be opened and closed independently of the valve switching rod 42. When the valve switching rod 42 is in the intermediate neutral position, the small diameter ball valve body 37 is moved to 37A by the valve switching rod 42.
The small diameter spherical valve element 37 does not push the large diameter spherical valve element 35, and the large diameter spherical valve element 35 presses against the valve seat 36. I'm closing this. When the valve switching rod 42 is in the innermost lowered position,
The small diameter ball valve body 37 is pushed by the valve switching rod 42 to the position 37B and moves away from the valve seat 38, and the large diameter ball valve body 35 is pushed by the small diameter ball valve body 37 and moves away from the valve seat 38.
Both of these are forced open to move away from 6.

45 is a safety valve provided between the ram cylinder 5 and the oil tank 8.

When raising the fork 1, operate the operating lever 21 of the operating handle 15 to move the valve switching rod 42.
is switched to the raised position so that the two ball valve bodies 35 and 37 of the switching valve 32 can be opened and closed independently of the valve switching rod 42. In this state, operate handle 1
By rocking 5 back and forth, as follows:
The pump 13 is activated and the ram 9 is gradually raised.
That is, when the plunger 20 of the pump 13 rises, the suction valve 30 opens, and oil is sucked into the pump cylinder 14 from the oil tank 8 through the suction oil passage 29. When the plunger 20 descends, the hydraulic pressure opens the discharge valve 33, further closes the small-diameter spherical valve body 37 of the switching valve 32, and opens the large-diameter spherical valve body 35, allowing oil to flow from the pump cylinder to the discharge oil passage 31 and into the switching valve. The oil is supplied to the ram cylinder 5 through the valve chamber 32A and the oil passage 34, and as a result, the ram 9 rises. Therefore, by repeatedly raising and lowering the plunger 20, the ram 9 gradually rises.

When moving the hand pallet lift, operate the operating lever 21 to switch the valve switching rod 42 to the neutral position, and move the small diameter ball valve body 37 of the switching valve 32 to the neutral position.
Force open only. When the plunger 20 of the pump 13 rises in this state, oil is sucked into the pump cylinder 14 from the oil tank 8 through the suction oil passage 29, as described above. Even when the plunger 20 descends, the small-diameter ball valve body 37 is forcibly opened, so the oil flows into the pump cylinder 1.
4, the oil only returns to the oil tank 8 through the discharge oil passage 31, the switching valve chamber 32A, and the oil return passage 44, and oil is not supplied to the ram cylinder 5 even if the plunger 20 moves up and down repeatedly. Further, even if the plunger 20 is repeatedly raised and lowered, the large diameter ball valve body 35 of the switching valve 32 does not open, so the oil in the ram cylinder 5 remains trapped. Therefore, even if the operating handle 15 is swung to move the hand pallet lift, and the plunger 20 of the pump 13 is raised or lowered, the ram 9 will not be raised or lowered, and the fork 1, that is, the load, will not be held in place. can be retained.

When lowering the fork 1, the operating lever 21 is operated to switch the valve switching rod 42 to the lowered position, and both of the two ball valve bodies 35, 37 of the switching valve 32 are forcibly opened. As a result, two ball valve bodies 3
5 and 37, the oil flows from the ram cylinder 5 to the oil passage 3 due to the weight of the fork 1 and the support frame 2.
4. The oil returns to the oil tank 8 through the switching valve chamber 32A and the oil return passage 44, and the ram 9 gradually descends.

According to the hydraulic jack of this invention, as mentioned above, the ram can be switched in three stages: ascending, neutral, and descending. In addition, the switching valve 32 is connected to the large diameter ball valve body 3.
5, small diameter ball valve body 37, valve shaft 39, coil spring 40
and a valve switching rod 42, and these are arranged in a linear oil passage 41, so that
The number of ball valve bodies 35, 37 constituting the switching valve 32 can be reduced, and the oil passage 41 for the switching valve 32 is linear and extremely simple. The structure is much simpler than the conventional one.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; Fig. 1 is a side view of a hand pallet lift employing the hydraulic jack of this invention, Fig. 2 is a rear view of the same, and Fig. 3 is a view of the first hand pallet lift.
FIG. 4 is a partially cutaway side view showing an enlarged portion of the hydraulic jack in FIGS. 5... Ram cylinder, 8... Oil tank, 14...
...Pump cylinder, 29...Suction oil passage, 30...
...Suction valve, 31...Discharge oil passage, 32...Switching valve, 32A...Switching valve chamber, 33...Discharge valve, 34
... Oil passage, 35 ... Large diameter ball valve body, 36 ... First
valve seat, 37... small diameter ball valve body, 38... second valve seat, 39... valve stem, 40... coil spring, 41...
...Stepped oil passage, 42... Valve switching rod, 44... Oil return passage.

Claims (1)

[Scope of utility model registration request] The oil tank and the pump cylinder communicate with each other via a suction oil passage via a suction valve, and the ram cylinder and the oil tank communicate with each other via a switching oil passage via a switching valve that can be switched to a raised position, a neutral position, and a lowered position. In a hydraulic jack for a hand pallet lift or the like in which a pump cylinder and a switching valve are communicated via a discharge oil passage via a discharge valve, the switching oil passage is a linear stepped oil passage 41 including a switching valve chamber 32A; One end of the switching valve chamber 32A and the ram cylinder 5
and an oil passage 34 communicating with the switching valve chamber 32A.
An oil return passage 44 that communicates the other end with the oil tank 8
In addition, one end of the discharge oil passage 31 is connected to an intermediate portion of the switching valve chamber 32A, and a portion closer to the oil passage 34 of the ram cylinder 5 than the discharge oil passage 31 is connected to the oil passage 34 of the switching valve chamber 32A. The side part becomes thicker and a stepped first valve seat 36 is provided in this part, and the part closer to the oil return passage 44 side of the oil tank 8 than the discharge oil passage 31 serves as the oil return passage of the switching valve chamber 32A. The portion on the 44 side is tapered and a step-shaped second valve seat 38 is provided at the lever portion, and the switching valve 32 is
This valve seat 3 is provided between the first valve seat 36 in the switching valve chamber 32A and the oil passage 34 of the ram cylinder 5.
a large-diameter spherical valve body 35 that opens and closes the valve seat 38;
A valve shaft 3 is fixedly inserted into the stepped oil passage 41 from the end on the large diameter spherical valve body 35 side and limits the amount of movement of the large diameter spherical valve body 35 in the opening direction away from the first valve seat 36.
9. A compression coil spring 40 attached to the valve shaft 39 to press the large-diameter spherical valve body 35 against the first valve seat 36 and bias it in a direction to close it, and a stepped oil passage 4
1 includes a valve switching rod 42 movably inserted from the end on the small diameter ball valve body 37 side, and the valve switching rod 42 has a
A raised position where the small diameter ball valve body 37 is not contacted, a neutral position where only the small diameter ball valve body 37 is pushed and only the second valve seat 38 is forcibly opened, and a large diameter ball valve body is pushed together with the small diameter ball valve body 37 through this. A hydraulic jack for a hand pallet lift, etc., which can be switched to a lowered position in which both valve seats 38 and 36 are forcibly opened by pushing 35.