JPH029125Y2 - - Google Patents

Description

[Detailed description of the invention] "Field of industrial application" This invention is applicable to hand lift trucks and forklift trucks that carry out cargo handling work, and are equipped with a hydraulic cylinder that raises and lowers a loading platform, and a plunger pump that drives this cylinder. The present invention relates to a hydraulic throttle valve device that is incorporated into a hydraulic throttle valve and constitutes a hydraulically operated valve that controls the application of hydraulic oil to the cylinder.

"Prior art"
As shown in the above publication, a truncated conical spool valve is installed between a cylinder port communicating with a hydraulic cylinder and a plunger pump port communicating with a plunger pump, and the opening/closing of the cylinder port is controlled by the large diameter body of the spool valve. At the same time, we have developed a technology to adjust the flow rate of hydraulic oil (control amount) by controlling the gap between the tapered surface of the spool valve and the valve seat.

``Problem that the invention seeks to solve'' However, in the hand lift trucks and forklift trucks, the hydraulic oil in the hydraulic cylinder is at a relatively high pressure, so it is necessary to reliably prevent oil leakage and maintain the pressure constant. In order to maintain the spool valve and valve seat, the finished surfaces of the spool valve and valve seat must be formed with extremely high machining accuracy, which increases costs and prevents dirt contained in the hydraulic fluid from adhering to the spool valve and valve seat. However, there were drawbacks such as the inability to maintain pressure and proper operation.

In addition, as shown in Special Publication No. 34-3540,
In a control valve for a gaseous fuel combustion device, a sleeve that forms a conical space is incorporated between a gas inlet and a gas outlet, and a spherical valve member is provided in this space, and the valve member allows the gas outlet to be opened. There is a technology that not only performs opening/closing control but also controls the gas flow rate (throttling amount adjustment) by controlling the gap between the valve member and the sleeve.

This type of control valve handles combustion gas, that is, compressible fluid, and even if the gap between the valve member and the sleeve is controlled, which has a relatively large range of variation, a sudden pressure drop will not occur. The space to be inserted may be conical, and the finished surface does not require extremely high machining precision, and furthermore, the movement of the valve member for gap control can be performed slowly, but the throttle valve device of the present invention is suitable for handling. With regard to the hydraulic oil in the hydraulic cylinders of forklift trucks and hand lift trucks, which are incompressible fluids, even the slightest change in the gap between the valve member and the sleeve will cause a sudden pressure drop, causing the load platform to drop rapidly. Therefore, in a structure in which a spherical valve member is fitted into a conical space, a structure that maintains a constant gap between the valve member and the sleeve is required, and it is extremely difficult to finish the finished surface of the conical space, which is extremely difficult to machine. Due to the differences in the properties of compressible fluids and incompressible fluids, the control valve of the above-mentioned publication has Applying this to forklift trucks and hand lift trucks would result in extremely dangerous cargo handling operations, and the handling operations would not be easy to perform.Instead of forming the conical space in the gas passage, By forming this conical space in the sleeve and incorporating it into the passage between the gas inlet and the gas outlet, it is possible to easily form a restricting passage, and the rolling of the spherical valve member can reduce dust. There was a problem in which the effects such as prevention of estimation cannot be achieved in the field of the present invention.

``Means for Solving the Problems'' However, the present invention provides an apparatus including a hydraulic cylinder for raising and lowering a cargo platform and a plunger pump for driving this cylinder, which includes a cylinder port communicating with the cylinder, and a plunger pump communicating with the cylinder. A throttle valve seat that forms a throttle passage having the same inner diameter and a constant length in the axial direction is incorporated between the plunger pump ports to be communicated, and a throttle ball that is movable within the throttle passage is also connected to the throttle passage. A pressure bulb is provided on the low-pressure side of the throttle valve seat that reduces pressure in the gap between the throttle balls, and communication between the cylinder port and the plunger pump port is controlled via the throttle bulb and the pressure bulb.

"Operation" Therefore, according to the present invention, by separately incorporating a throttle valve seat that forms a throttle passage in the middle of the oil path between the cylinder port and the plunger pump port,
Compared to conventional methods, the throttle passage and throttle valve seat can be formed easily and inexpensively with high processing accuracy, and by loosely inserting the throttle ball into the throttle passage, which has the same inner diameter and a constant length in the axial direction. Compared to a conical space, the aperture ball can contact and roll more easily with respect to the aperture passage, thereby improving the removal effect of dust in the hydraulic oil adhering to the aperture passage and the aperture ball, thereby eliminating this dust clogging. In addition, the gap between the throttle passage and the throttle ball can be kept the same as long as the throttle ball moves in the throttle passage, and the gap between the throttle passage and the throttle ball can be changed by minute movement of the throttle ball. The flow rate (throttling amount) can be adjusted safely and quickly by moving the throttle ball without causing a sudden pressure drop. Furthermore, when the application of high-pressure oil is interrupted, The return action of the throttle ball presses the pressure ball, which closes the oil passage between the cylinder port and the plunger port, and quickly prevents high-pressure oil from flowing out from the cylinder side to the pump side. For example, it is possible to prevent inconveniences such as high-pressure oil in the cylinder returning to the plunger pump during suction operation and giving a shock to the pumping handle that operates the pump, and to constantly move the throttle ball and the pressure ball as one unit. It is possible to prevent these delays in operation, appropriately control the communication between the cylinder port and the plunger port, and drive and operate the cylinder and plunger pump in accordance with the cargo handling work conditions.

"Embodiment" An embodiment of the present invention will be described below in detail based on the drawings. Fig. 1 is a schematic plan view of the hand lift truck, and Fig. 2 is a drawing of the same side. , 3 is a jacking device that supports the rear end of the platform 1 and raises and lowers it, and 3 has the rear wheels 4, 4 pivotally supported on the lower part thereof, and 5 has the rear wheels 4, 4 attached to the lower end via an axle 6. A ram cylinder, 7 is a ram piston whose semicircular spherical tip 9 is brought into contact with the chevron-shaped support part 8 of the load platform 1, 10 is a hydraulic base fixedly supported in the middle of the ram cylinder 5, and 11 is a cylinder below the base 10. A bearing plate 14 is fixed to the cylinder 5 circumferential side on the upper surface of the base 10 and connects the arm 12 and the rod 13, which are rotatably provided on the 5 circumferential side and project the front wheel 2 in proportion to the upward movement of the piston 7. 15 is a plunger pump for supplying pressure oil to the cylinder 5; 16 is a handle base bracket fixedly installed above the back of the tank 14; 17 is supported by the bracket 16 via a rotation fulcrum pin 18; A handle base 21 is formed by pivotally supporting a pressure roll 20 which is brought into contact with the plunger piston 19 of the pump 15; It is a handle for operation and push/pull operation.

As shown in FIGS. 4 to 10, the base 1
0 is provided with a hydraulically operated valve 23 and an overload prevention valve 24. Suction bulb 25 of the operation valve 23
The tank port 26 is connected to the plunger pump port 27 through the valve 23, and the port 27 is connected to the cylinder port 30 through the pressure bulb 28 and the throttle bulb 29 of the valve 23, and is formed in the cylindrical throttle valve seat 31. The throttle ball 29 is loosely inserted into the throttle passage 32 having the same inner diameter and a constant length in the axial direction. Furthermore, the throttle valve chamber 33 that encloses the throttle valve seat 31 is communicated with the cylinder port 30, and a spring 35 is stretched between the throttle valve seat 31 and a plug 34 that opens the chamber 33. The throttle valve seat 31 is brought into pressure contact with the end face 36.

In addition, the pressure ball 28 is disposed on the low pressure side of the throttle valve seat 31 that reduces the pressure in the gap (for example, 5/100 mm) between the throttle ball 29 and the throttle passage 32, and the cylinder 5 While the throttle ball 29 is brought into contact with the pressure bulb 28 by the working oil pressure, the pressure ball 28 prevents the high-pressure oil whose pressure is reduced by the throttle ball 29 from flowing out, and A tapered passage 37 is formed on the high pressure side.
As shown in FIG. 6, a relief hole 38 is provided at the opening edge of the throttle passage 32, and when the pressure bulb 28 comes into contact with the opening edge of the passage 32, the hydraulic oil flows through the relief hole 38 and the 7. As shown in figure, throttle valve seat 3
The end of the spring 35 that is brought into pressure contact with the spring 35 is bent in the shape of a square so as to close the inner hole of the spring 35 to form a stopper 35a, and the stopper 35a
When the plunger pump 15 moves into the tapered passage 37, the throttle ball 29 comes into contact with the stopper 35a and prevents the throttle ball 29 from entering the inner hole of the spring 35. When the plunger pump 15 is operated, the suction ball 25 is The pump 15 is opened to draw the hydraulic oil from the tank 14 into the pump 15, while the pressure bulb 28 and the throttle bulb 29 are opened to feed the high pressure oil from the pump 15 to the cylinder 5. Therefore, the throttle ball 29 moves while attached to the pressure ball 28, and when the pump 15 finishes pumping high-pressure oil to the cylinder 5, the pressure ball 28 is quickly closed and the high-pressure oil returns from the cylinder 5. It is configured to eliminate the pushing back action of the handle 21 and prevent the generation of pumping impact on the handle 21.

Next, a pressure release push rod 39 is provided on the operation valve 23, and by pushing the push rod 39 against the return spring 40, first, only the suction ball 25 is opened and the plunger pump 15 is opened, as shown in FIG. For dry operation, the switching valve 23
is switched to the neutral operation state, and by further pushing the put rod 39, the suction bulb 25 is brought into contact with the pressure bulb 28 as shown in FIG. The high-pressure oil in the cylinder 5 whose pressure has been reduced through the gap (5/100 mm) is gradually returned to the tank 14, and the pressure in the cylinder 5 is slowly released, and the push rod 39 is further pushed in, as shown in Fig. 10. The pressure ball 28 is brought into contact with the opening edge of the throttle passage 32 as shown in FIG. The high-pressure oil in the cylinder 5 is quickly returned to the tank 14 through the cylinder 5, and the pressure in the cylinder 5 is quickly released.

As shown in FIGS. 11 to 13, a cap 41 is integrally formed on the upper end of the push/pull operation handle 21, and the base end of the hydraulic operation switching lever 42 is inserted into the internal space of the cap 41. The base end of the lever 42 is loosely fitted and pivoted on a pin 43 fixed to the cap 41, and a suspension rod 44 is loosely inserted into the internal space of the handle 21, and the rod is inserted into the upper edge recess 42a of the lever 42. Hook part 44a at the upper end of 44. The outer end of the push rod 39 protruding from the side of the base 10 is
One end of the hydraulic operating arm 45 is brought into contact with the arm 45, and the middle of the arm 45 is pivotally supported on the flange 46 of the base 10 via a pin 47.
The other end of 5 is connected to the oil tank 14 and the plunger pump 1.
The arm 45 extends on the upper surface of the base 10 between the
A suspension bolt 48 is fixed to the other end so that its length can be adjusted. The lower end of the rod 44 and the upper end of the bolt 48 are connected by a chain 49, and the chain 49 is stretched so as to be bendable in the swing direction of the handle 21, and the inner ends of the left and right pivot pins 18, 18 are connected. A chain guide pin 50 is installed on the rear side of the bearing portions 16a, 16a of the handle base bracket 16 into which the chain 49 is inserted, and when the handle 21 is rocked and rotated using the pins 18, 18 as fulcrums, the middle of the chain 49 is bending the chain 49 by contacting the pin 50, preventing the chain 49 from contacting the plunger pump 15, and aligning the axes of the pins 18, 18 with the bent portion of the chain 49; Bending the chain 49 with the valve 23 and arm 45 stationary at a certain position,
Plunger pump 15 by swinging handle 21
Form so that it can be operated.

Further, a raising operation notch 51 and a neutral operation notch 52 for engaging the intermediate lower edge of the lever 42 are formed in the opening 53 of the cap 41, and a lowering operation notch 54 is formed above the raising operation notch 51, and a neutral operation notch 52 is formed above the raising operation notch 51. 52 Upper and lower operation notches 54
By forming an arcuate guide 55 in the aperture 53 and engaging the lever 42 with the lifting operation notch 51, the suction ball 23 of the operation valve 23 can be operated as shown in FIGS. 4 and 5. Close the tank port 26 and plunger pump port 27,
By switching the valve 23 to the upward operation state to perform the pump action, and engaging the lever 42 with the neutral operation notch 52 as shown in FIG. 12, the push rod 39 is activated as shown in FIGS. 8 and 11. Push in to open the suction bulb 25 and open each port 2.
6 and 27 are electrically connected, the valve 23 is switched to the neutral operation state, the plunger pump 15 is operated idly, and then the lever 42 is lifted to close the guide 5.
5 to the lowering operation notch 54, the push rod 39 is pushed further to bring the suction bulb 25 into contact with the pressure bulb 28, and the pressure bulb 28 is released, causing the squeeze bulb to open as shown in FIG. 29 and the throttle passage 32, and by pulling up the lever 42 to the upper end of the lowering operation notch 54 when the load is light, the pressure bulb is released as shown in FIG. 28, the throttle ball 29 is moved to the tapered passage 37 of the throttle valve seat 31, the throttle action of the throttle ball 29 is released, and the high pressure oil in the cylinder 5 is rapidly drawn out, and the high pressure oil in the cylinder 5 is removed in multiple stages. It is formed so that the flow returns to the tank 14 at a flow rate of .

The present invention is constructed as described above, and when loading cargo on a pallet (not shown) or the like onto the platform 1, the hydraulic operation switching lever 42 is engaged with the lifting operation notch 51, and the lever is placed upright. When the push/pull operation handle 21 is swung around the fulcrum pin 18,
Hydraulic oil in the tank 14 is sucked into the plunger pump 15 via the suction bulb 25, pressure oil from the plunger pump 15 is fed under pressure to the cylinder 5 via the pressure bulb 28 and the throttle bulb 29, and the ram piston 7 protrudes from the mounting base. Move 1 up. At this time, the suction bulb 2
5. Only the hydraulic pressure is applied to the pressure bulb 28 and the throttle bulb 29, so the suction bulb 25 and pressure bulb 28 quickly open and close in conjunction with the plunger pump 15. Compare the operation of the pump 15 with the handle 21. This can be done with a small force, and since the throttle ball 29 is pressed against the pressure ball 28 by the high pressure oil in the cylinder 5, the high pressure oil in the cylinder 5 flows back into the pump 15 due to the delay in closing the pressure ball 28, and the handle 21 To prevent a sudden upward movement of the handle 21 and to smoothly perform a pumping operation of a handle 21.

In addition, when moving the luggage platform 1 with it raised to an appropriate height as described above, the switching lever 42 is engaged with the neutral operation notch 52 as shown in FIG. 3
9, the suction bulb 25 is opened and supported as shown in FIG. 8, and the valve 23 is switched to the neutral operation state as shown in FIG. The port 30 is closed by the pressure bulb 28, the ram piston 7 and the load platform 1 are fixedly supported, and in this state, the handle 21 is pushed or pulled to transport the load.

As shown above, the handle 2 is centered around the fulcrum pin 18.
When folding down 1 and performing lifting and lowering operations and push/pull operations,
The middle part of the chain 49 connecting the suspension rod 44 and the bolt 48 contacts the guide pin 50, and the middle part of the chain 49 located on the axis of the fulcrum pin 18 is bent, and the handle 2 is centered on the fulcrum pin 18.
The operating arm 45 and the push rod 39 are kept stationary at a constant position regardless of the displacement of the operating arm 45 and the push rod 39.

Furthermore, when lowering the cargo platform 1 to unload cargo loaded on a pallet or the like, when the switching lever 42 shown in FIGS. 11 and 12 is pulled up, the upper edge of the lever 42 comes into contact with the arcuate guide 55, Guided by the guide 55, the lever 42 moves to the lowering operation notch 54. Then, the operating arm 45 is displaced via the suspension rod 44 and the push rod 39 is pushed in, and the suction ball 25 is brought into contact with the pressure ball 28 as shown in FIG. Due to the throttle action of the gap in the throttle passage 32, the high pressure oil in the cylinder 5 is gradually flowed out toward the tank 14, and the cargo platform 1 is gently lowered. When the platform 1 is empty and under a light load, push the push rod 39 further by operating the lever 42;
As shown in FIG. 10, the squeeze ball 29 is
is moved to the tapered passage 37 of the throttle valve seat 31, the throttle action of the throttle ball 29 is released, the high pressure oil in the cylinder 5 is rapidly flowed out toward the tank 14, and the cargo platform 1 is suddenly lowered. By releasing the tensioned lever 42, the lever 42 automatically engages the lower lifting operation notch 51, and the valve 23 is switched to the lifting operation state as shown in FIGS. 4 and 5. be.

"Effects of the Invention" As is clear from the above embodiments, the present invention provides an apparatus that is equipped with a hydraulic cylinder 5 for raising and lowering a cargo platform 1 and a plunger pump 15 that drives this cylinder 5, which communicates with the cylinder 5. A throttle valve seat 31 that forms a throttle passage 32 having the same inner diameter and a constant length in the axial direction is installed between the cylinder port 30 that communicates with the pump 15 and the plunger pump port 27 that communicates with the pump 15. A pressure ball is provided on the low pressure side of the throttle valve seat 31 that reduces the pressure in the gap between the throttle passage 32 and the throttle ball 29, and the cylinder port 30 and the plunger pump port 27 are connected to the throttle ball. 29 and pressure bulb 28, and by separately incorporating a throttle valve seat 31 that forms a throttle passage 32 in the middle of the oil path between the cylinder port 30 and the plunger pump port 27, the throttle is reduced compared to the conventional one. The passage 32 and the throttle valve seat 31 can be formed easily and inexpensively with high processing accuracy, and by loosely inserting the throttle ball 29 into the throttle passage 32, which has the same inner diameter and a constant length in the axial direction, a conical shape can be formed. The aperture ball 29 can easily contact and roll against the aperture passage 32 compared to the shape of the space.
2 and the throttle ball 29 can be improved to eliminate dust in the hydraulic oil adhering to the throttle ball 29, thereby eliminating malfunctions caused by this dust clogging. The flow rate is the same as long as the throttle ball 29 moves, and the flow rate is maintained by the movement of the throttle ball 29 without causing a sudden pressure drop due to a change in the gap between the throttle ball 29 and the throttle passage 32 due to minute movements of the throttle ball 29. (Amount of throttle) can be adjusted safely and quickly, and furthermore, when the application of high-pressure oil is interrupted, the throttle ball 29 presses the pressure ball 28 due to the return action of this high-pressure oil, and this pressure The ball 28 closes the oil passage between the cylinder port 30 and the plunger pump port 27, and can quickly prevent high-pressure oil from flowing out from the cylinder 5 side to the pump 15 side. For example, when the plunger pump 15 is in suction operation. This eliminates inconveniences such as the high pressure oil in the cylinder 5 returning and giving a shock to the pumping handle 21 that operates the pump 15.
The cylinder port 30 and the plunger pump port 27 can be controlled to communicate with each other by integrally moving the cylinder port 30 and the plunger pump port 27, preventing delays in their operation, and quickly adjusting the cylinder 5 and plunger pump 15 to the cargo handling work conditions. It has practical and remarkable effects such as being able to be driven and operated.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a hand lift truck showing an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG.
The figure is a cross-sectional side view of the jacking device, Figure 4 is a plan view of the hydraulic base, Figure 5 is an enlarged cross-sectional view of the main parts, and Figure 6 is a cross-sectional side view of the jacking device.
7 and 7 are partial views thereof, FIGS. 8 to 10 are operational explanatory views of the main parts, and FIGS. 11 to 13 are enlarged sectional views of the handle. 1... Luggage platform, 5... Hydraulic cylinder, 15... Plunger pump, 27... Plunger pump port, 28... Pressure bulb, 29... Throttle bulb, 30... Cylinder port, 31... Throttle valve seat, 32... Throttle passage.

Claims (1)

[Scope of utility model registration request] a hydraulic cylinder 5 that raises and lowers the cargo platform 1;
Plunger pump 15 that drives this cylinder 5
In the apparatus, a throttle passage 3 having the same inner diameter and a constant length in the axial direction is provided between the cylinder port 30 communicating with the cylinder 5 and the plunger pump port 27 communicating with the pump 15.
2, a throttle ball 29 movable into the throttle passage 32, and a pressure ball on the low pressure side of the throttle valve seat 31 that reduces the pressure in the gap between the throttle passage 32 and the throttle ball 29. and the cylinder port 30 and the plunger pump port 27
A hydraulic throttle valve device characterized in that communication is controlled via the throttle ball 29 and the pressure ball 28.