JP2003054886A - Hydraulic jack device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a plunger pump 15, a hydraulic circuit structure and a plunger pump 15 operation structure, and reduce manufacturing cost and size. SOLUTION: In the hydraulic jack device, a cargo handling hydraulic cylinder 5 is driven by the plunger pump 15. It is characterized by that a plunger head 35 is formed on a plunger 19 going in and out a cylinder body 33 of the plunger pump 15, a pressurizing chamber 36 and a back pressure chamber 37 are formed in an interior of the cylinder body 33 via the plunger head 35, a quick raising action is carried out of operating the hydraulic cylinder 5 by delivery oil of the plunger head 35 by using the pressurizing chamber 36, and a slow raising action is carried out of operating the hydraulic cylinder 5 by delivery oil of the plunger 19 by short-circuiting the pressurizing chamber 36 and the back pressure chamber 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic jack device provided in a cargo handling vehicle such as a pallet truck for carrying a load on a pallet and a lift truck for moving a load or a work platform up and down.

[0002]

Conventionally, there is a technique of mounting a loading platform on a carriage so as to be able to move up and down and driving a hydraulic cylinder for raising the loading platform by a plunger pump.
When changing the lifting speed of the loading platform, multiple plunger pumps with different capacities can be installed and used selectively, the operation stroke of the plunger pump can be changed, and the oil flow rate of the plunger pump that operates the hydraulic cylinders can be controlled. It is necessary to simplify the structure of the plunger pump, simplify the structure of operating the plunger pump, simplify the hydraulic circuit that connects the hydraulic cylinder and the plunger pump, etc., and reduce the manufacturing cost and simplify the structure. There is a problem that it cannot be easily made compact.

[0003]

SUMMARY OF THE INVENTION However, according to the present invention, in a hydraulic jack device in which a loading hydraulic cylinder is driven by a plunger pump, a plunger head is provided in a plunger to be inserted into and removed from a cylinder body of the plunger pump, and the plunger head is provided through the plunger head. The pressurizing chamber and the back pressure chamber are formed inside the cylinder body, and the hydraulic cylinder is actuated by the oil discharged from the plunger head using the pressurizing chamber. The hydraulic cylinder operates a slow lift operation by the oil discharged from the plunger. The difference between the plunger diameter of the plunger pump and the diameter of the plunger head is larger than the amount of oil discharged per stroke of the plunger per stroke of the plunger head. Increase the amount of discharged oil to create a hydraulic cylinder per stroke of the plunger pump. Since varying the speed, for example, it is not necessary to provide a plurality of plunger pump, also there is no need to change the operation stroke of the plunger pump,
In addition, it is not necessary to control the oil flow rate of the plunger pump that operates the hydraulic cylinder, and it is possible to easily simplify the structure of the plunger pump and the hydraulic circuit and the operating structure of the plunger pump, thereby reducing the manufacturing cost and downsizing. Can be easily achieved.

Further, the pressurizing chamber and the back pressure chamber are hydraulically connected via a switching valve that automatically opens and closes when the load on the hydraulic cylinder increases or decreases, and the switching valve opens when the load on the hydraulic cylinder exceeds a certain level. The operating force of the plunger pump can be prevented from becoming too small or too large because it will be closed below a certain level, and it is possible to carry out early or late lift operation, and It can be easily improved.

Further, the switching valve is incorporated in the plunger head, and it can be formed by increasing the dimension of the plunger head in which the switching valve is provided, as compared with the conventional structure in which the switching operation is performed at a constant speed. For example, a plunger pump is operated. It is possible to eliminate the problem that the pumping fulcrum shaft becomes high, to configure without changing the conventional component arrangement structure and external size, and to replace the plunger having the plunger head with one with a different diameter. The specifications can be easily changed for lift (for example, 3 tons) and small lift (for example, 1 ton).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side view of the whole, FIG. 2 is a plan view of the same, and FIG. 3 is a side view of essential parts. In FIG. 1, reference numeral 1 is a fork of two forks in which front running wheels 2, 2 are attached so as to project downward. The shape carrier 3 has a jack device for supporting the rear wheels 4 for traveling on the lower part thereof to support the rear end of the carrier 1 and raises and lowers it. 5 is a cylinder head 5b at the lower end via an axle 6. Hydraulic cylinders for mounting the rear wheels 4, 4 are ram-type pistons 7 for abutting against the supporting portion 8 of the cargo bed 1 via a sphere 9.
Is a hydraulic base fixedly supported substantially horizontally in the middle of the cylinder 5, and 11 is rotatably provided on the circumferential side of the cylinder 5 below the hydraulic base 10 to project the front wheel 2 in proportion to the upward movement of the piston 7. A bearing plate that connects the arm 12 and the rod 13 is provided, 14 is an oil tank that is fixedly installed on the upper surface of the hydraulic base 10 on the circumference of the cylinder 5, 15 is a plunger pump that sends pressurized oil to the cylinder 5, and 16 is the back of the tank 14. A handle bracket fixed to the upper side, 17
Is a handle base which is supported by the bracket 16 through a pivoting fulcrum pin 18 and axially supports a pressure roll 20 that abuts against a plunger 19 of the pump 15, and 21 is a loop-shaped grip 21a at the upper end. A pumping handle is provided for raising and lowering and pushing and pulling the base end of which is connected and fixed to the handle base 17. Reference numeral 22 is a return spring that projects the plunger 19 and supports the handle 21 in an upright position. Tank 14
A handle bracket 16 is provided so as to stand upright and tilt backward.

Further, as shown in FIGS. 4 to 7, a lifting operation valve 23 and an overload prevention valve 24 are provided on the hydraulic base 10. Then, the tank port 26 is connected to the pump port 27 via the suction ball 25 of the operation valve 23.
Further, the pump port 27 is communicated with the cylinder port 29 through the pressure ball 28 of the operation valve 23. In addition, the pressure ball 28 and the plug 3 for enclosing the pressure ball 28
A throttle ball 31 is provided in the back pressure chamber between 0 through a valve seat, and a return spring is stretched between the plug 30 and the throttle ball 31,
This spring force causes the throttle ball 31 to come into contact with the pressure ball 28. When the plunger pump 15 is operated, the suction ball 2
The hydraulic oil in the tank 14 is sucked into the pump 15 via 5,
Open the pressure ball 28 against the return spring to open the cylinder 5
The pressure oil from the pump 15 is sent to.

Further, the operation valve 23 is provided with a pressure release push rod 32, and the push rod 32 is pushed in by operating the pressure release lever 33 on the upper end side of the handle 21 to keep only the suction ball 25 open first. Then, the operation valve 23 is switched to the neutral operation state in order to idle-operate the plunger pump 15, while the push rod 32 is operated.
By further pushing the suction ball 25 into the pressure ball 28
The pressure port 28 against the return hydraulic pressure from the cylinder 5 to open the pressure ball 28, and the cylinder port 29 is connected to the tank port 2.
6, the pressure oil of the cylinder 5 is returned to the tank 14 at a desired fluid pressure by the hydraulic throttling action of the pressure ball 28 and the throttling ball 31.

Further, the lower end of the cylindrical cylinder body 33 of the plunger pump 15 is welded and fixed to the hydraulic base 10, the cylinder head 34 is detachably screwed to the upper end side of the cylinder body 33, and the cylinder body is inserted through the cylinder head 34. A plunger head 35 is integrally formed on the lower end of the plunger 19 to be inserted into the cylinder 33, and the interior of the cylinder body 33 is vertically divided by the plunger head 35. A pressurizing chamber 36 is formed on the lower side of the cylinder body 33 and a back pressure is provided on the upper side. The chamber 37 is formed.

Further, the communication passage 3 opened to the back pressure chamber 37.
8 is provided in the plunger 19, a suction passage 39 and a discharge passage 40 that open to the pressurizing chamber 36 are provided in the plunger head 35, and the suction passage 39 and the discharge passage 40 are connected to the back pressure chamber 37.
8 and the suction check valve 43 that is brought into contact with the valve seat 42 by the pressure spring 41 is connected to the suction passage 39.
To be installed. Further, a discharge check valve 44 for returning the oil in the back pressure chamber 37 to the pressure chamber 36 side is provided in the discharge passage 40.

When the plunger 19 is pushed down against the return spring 22, the load of the loading platform 1 is light and the pressure of the pressure chamber 36 for sending pressure to the hydraulic cylinder 5 is low. The check valve 43 is kept in contact with the valve seat 42 by 41, the oil in the pressurizing chamber 36 is pumped to the hydraulic cylinder 5 by the plunger head 35 via the pressure ball 28, and the piston 7 rises per stroke of the plunger 19. The size is increased, and the platform 1 is quickly lifted. Further, as shown in FIGS. 6 and 7, an auxiliary suction valve 45 is provided in parallel with the suction ball 25, and when the return spring 22 causes the plunger 19 to withdraw, the oil tank 14 passes through both the suction ball 25 and the suction valve 45. Is sucked into the pressurizing chamber 36, and the suction valve 45 compensates for the shortage of the amount of oil sucked by the suction ball 25.

On the other hand, the plunger 1 is resisted against the return spring 22.
When the load of the loading platform 1 is heavy and the hydraulic pressure of the pressurizing chamber 36 for pumping to the hydraulic cylinder 5 is high by pressing down 9, the check valve 43 is moved from the valve seat 42 against the pressurizing spring 41 during heavy load work. Away, the oil in the pressurizing chamber 36 flows into the back pressure chamber 37,
Oil is pressure-fed from the pressurizing chamber 36 to the hydraulic cylinder 5 via the pressure ball 28 by the amount of the plunger 19 entering the cylinder body 33, and the lifting dimension of the piston 7 per stroke of the plunger 19 is reduced, so that the loading platform 1 is Operate late-frying.

As is clear from the above, in the hydraulic jack device in which the cargo handling hydraulic cylinder 5 is driven by the plunger pump 15, the plunger head 35 is provided in the plunger 19 which is inserted into and removed from the cylinder body 33 of the plunger pump 15, and the plunger head 35 is provided. A pressurizing chamber 36 and a back pressure chamber 37 are formed inside the cylinder main body 33 via the pressurizing chamber 36, and the hydraulic cylinder 5 is actuated by the oil discharged from the plunger head 35 using the pressurizing chamber 36. Three
6 and the back pressure chamber 37 are short-circuited, and the hydraulic oil is discharged from the plunger 19 to operate the hydraulic cylinder 5 in a delayed lifting operation. The difference between the diameter of the plunger 19 of the plunger pump 15 and the diameter of the plunger head 35 is 1
Plunger head 35 rather than the amount of oil discharged per stroke
The amount of discharge oil per one stroke is increased and the operating speed of the hydraulic cylinder 5 per one stroke of the plunger pump 15 is made different. For example, it is not necessary to provide a plurality of plunger pumps 15, and the operating stroke of the plunger pump 15 is There is no need to change it, and there is no need to control the oil flow rate of the plunger pump 15 that operates the hydraulic cylinder 5, and the structure of the plunger pump 15 and the hydraulic circuit is simplified, and the operating structure of the plunger pump 15 is also simplified. Aim for cost reduction and compactness.

Further, the pressurizing chamber 36 and the back pressure chamber 37 are hydraulically connected via a suction check valve 43, which is a switching valve that is automatically opened / closed according to an increase / decrease in a cargo handling load of the hydraulic cylinder 5. The suction check valve 43 opens when the load is above a certain level and closes when the load is less than a certain level to prevent the operating force of the plunger pump 15 from becoming too small or too large, so that a quick lifting operation or a slow lifting operation can be performed. In order to improve the handling operability such as the operation of the plunger pump 15, the suction check valve 43 is attached to the plunger head 35.
Can be formed by enlarging the size of the plunger head 35 provided with the switching valve 43, as compared with the conventional structure in which the pump is incorporated and lifting operation is performed at a constant speed.
A pivoting fulcrum pin 18 which is a pumping fulcrum shaft for operating 5
It eliminates the problem that the height becomes high and makes it possible to configure with almost no changes to the conventional component arrangement structure and external size,
By exchanging the plunger 19 provided with the plunger head 35 with one having a different diameter, the specifications are changed for a large lift force (for example, 3 tons) and a small lift force (for example, 1 ton).

Further, as shown in FIGS. 8 to 13, a lift hydraulic cylinder 49 and a mast 50 are erected on a carriage 48 provided with front and rear wheels 46 and 47, and a loading platform 51 is mounted on the mast 50.
In a lift truck that lifts and lowers a load to be loaded on the loading platform 51 to a high position.
An oil tank 52 is provided on the outside, a bracket 53 is fixed to the oil tank 52, a base 55 is rotatably supported by the bracket 53 via a pumping fulcrum shaft 54, and a pedal 56 for stepping operation is attached to the base 55. At the same time, the hydraulic base 57 is fixed to the carriage 48, and the cylinder 49
And the tank 52 is erected on the hydraulic base 57,
Similar to the pallet truck of FIGS. 1 to 7 described above, the plunger pump 15 is provided on the hydraulic base 57, and the plunger pump 15 is operated by the pressure roll 20 of the base 55 by the stepping operation of the pedal 56, and the hydraulic cylinder 49 of the hydraulic cylinder 49 is operated. Advance the ram type piston 58 upward,
This is for raising the loading platform 51, and similar to the above, the loading platform 51
When the load is small, the hoisting operation is performed quickly, and when the load is large, the hoisting operation is performed slowly, and it is not necessary to increase the vertical width dimension of the plunger pump 15.
6 can be installed at a low position and easily operated.

As shown in FIGS. 11 to 13, a pressure release valve 59 for returning pressure oil from the hydraulic cylinder 49 to the oil tank 52 is provided, and a connecting oil passage between the hydraulic cylinder 49 and the pressure release valve 59 is provided in the middle. A sudden drop prevention valve 60 is provided to lower the platform 51 at a slow speed when the pressure release valve 59 is opened even when the platform 51 is heavy.

Further, as shown in FIG. 14, instead of the pedal 56 shown in FIG. 10, a lever 61 for rowing operation is attached to the base 55, and the plunger pump 15 is driven by the rowing operation of the lever 61. In addition, the platform 51 can also be operated for early lifting or late lifting.

[0018]

As is apparent from the above-described embodiments, the present invention is a hydraulic jack device in which the cargo handling hydraulic cylinder 5 is driven by the plunger pump 15, and the plunger 1 for moving in and out of the cylinder body 33 of the plunger pump 15.
9, the plunger head 35 is provided, and the plunger head 3
5, a pressurizing chamber 36 and a back pressure chamber 37 are formed inside the cylinder body 33, and the hydraulic cylinder 5 is actuated by the oil discharged from the plunger head 35 using the pressurizing chamber 36. The pressure chamber 36 and the back pressure chamber 37 are short-circuited so that the hydraulic cylinder 5 is actuated by the oil discharged from the plunger 19 so that the plunger 19 is displaced by the difference between the diameter of the plunger 19 of the plunger pump 15 and the diameter of the plunger head 35. Since the discharge oil amount per stroke of the plunger head 35 is made larger than the discharge oil amount per stroke of 19 and the operating speed of the hydraulic cylinder 5 per stroke of the plunger pump 15 is made different, for example, a plurality of plunger pumps 15 need not be provided, the operation stroke of the plunger pump 15 need not be changed, and the hydraulic cylinder It is not necessary to control the oil flow rate of the plunger pump 15 for activating 5, and the plunger pump 15 and the hydraulic circuit structure can be simplified and the operation structure of the plunger pump 15 can be simplified, and the manufacturing cost can be reduced. It can be easily made compact.

Further, the pressurizing chamber 36 and the back pressure chamber 37 are hydraulically connected via the switching valve 43 which is automatically opened / closed by the increase / decrease of the cargo handling load of the hydraulic cylinder 5, and the load of the hydraulic cylinder 5 is not less than a certain level. Since the switching valve 43 is opened and closed below a certain level, it is possible to prevent the operating force of the plunger pump 15 from being excessively small or excessively large, and to perform the early or late lifting operation. It is possible to easily improve handling operability such as operation of the plunger pump 15.

Further, the switching valve 43 is incorporated in the plunger head 35, and it can be formed by making the size of the plunger head 35 provided with the switching valve 43 larger than that of the conventional structure in which the switching operation is performed at a constant speed. It is possible to eliminate the problem that the pumping fulcrum shaft 18 for operating 15 becomes high, and it is possible to configure without changing the conventional component arrangement structure and external size almost.
By exchanging the plunger 19 provided with the plunger head 35 with one having a different diameter, the specifications can be easily changed for a large lift force (for example, 3 tons) and a small lift force (for example, 1 ton).

[Brief description of drawings]

FIG. 1 is an overall side view of a pallet truck.

FIG. 2 is a plan view of the same.

FIG. 3 is a side view of a hydraulic cylinder section.

FIG. 4 is a side view of a plunger pump section.

FIG. 5 is a perspective view of a hydraulic base portion.

FIG. 6 is a plan view of the same.

FIG. 7 is a hydraulic circuit diagram.

FIG. 8 is an overall side view of a lift truck.

FIG. 9 is a plan view of the same.

FIG. 10 is a side view of the plunger pump section.

FIG. 11 is a plan view of a hydraulic base.

FIG. 12 is a plan view of the same section.

FIG. 13 is a hydraulic circuit diagram.

FIG. 14 is an overall side view showing a modified example of FIG.

[Explanation of symbols]

5 hydraulic cylinder 15 Plunger pump 19 Plunger 33 Cylinder body 35 Plunger head 36 Pressure chamber 37 Back pressure chamber 43 Check valve for suction (switching valve)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3F333 AA03 AB07 BA03 BD02 FH04                 3H071 AA03 BB01 CC34 DD03 DD12                       DD13                 3H075 AA02 BB03 CC35 CC36 DA04                       DA09 DB13 DB38

Claims (3)

[Claims] 1. A hydraulic jack device in which a loading hydraulic cylinder is driven by a plunger pump, wherein a plunger head is provided on a plunger that moves in and out of a cylinder body of the plunger pump, and a pressurizing chamber and a back are provided inside the cylinder body via the plunger head. The pressure chamber is formed, and the hydraulic cylinder is actuated by the oil discharged from the plunger head using the pressure chamber, and the hydraulic cylinder is actuated by the oil discharged from the plunger by short-circuiting the pressure chamber and the back pressure chamber. A hydraulic jack device characterized by a delayed lifting operation. 2. The hydraulic jack device according to claim 1, wherein the pressurizing chamber and the back pressure chamber are hydraulically connected via a switching valve that automatically opens and closes according to an increase or decrease in the load handling load of the hydraulic cylinder. 3. The hydraulic jack device according to claim 2, wherein a switching valve is incorporated in the plunger head.