JP3075428B2 - Hydraulic lift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic lift, and more particularly to a buried two-post hydraulic lift.

[0002]

2. Description of the Related Art Recently, there have been many cases of constructing a vehicle maintenance shop on a floor, and the length of a hydraulic lift cylinder has been shortened.
There is a demand for a hydraulic lift capable of obtaining a longer lifting stroke with respect to the restricted burial depth, and various hydraulic lifts of a two-stage type have been conventionally proposed as hydraulic lifts meeting this demand.

[0003] In addition, large heavy objects such as vehicles, especially those having no particularly heavy parts such as an engine room in the center, are supported by front and rear or left and right hydraulic lifts in order to maintain the stability of lifting and lowering. The method of lifting and lowering is widely used, and this method is called a two-post hydraulic lift.

In the two-post type hydraulic lift as described above, since different loads may be applied to both hydraulic lifts, it is necessary to raise and lower both hydraulic lifts in synchronization.
If there is a change in the lifting distance between the two, the heavy object is inclined, and if the inclination is increased, there is a risk that the heavy object will fall. Therefore, various lift elevating and tuning devices have been proposed.

[0005] However, it is originally difficult to raise and lower the two-post type hydraulic lift synchronously. In particular, when an eccentric load is applied to a pair of hydraulic lifts, it becomes more difficult to synchronize the lifting distance. doing. In other words, when oil is branched from one hydraulic unit and oil is supplied to both hydraulic units,
The flow rate is not always equally divided at the branch point of the oil flow path, and on the side with a large load, the amount of oil pumped decreases corresponding to the difference in internal pressure, so the vertical movement cannot be synchronized. It will be easier.

Therefore, as a conventional tuning device, a system has been proposed in which two hydraulic units having the same performance are used and each lift is driven by each hydraulic unit. This method uses a general pump for the hydraulic unit,
When an eccentric load is applied, there is no difference that tuning is difficult in response to the difference in internal pressure as described above, and a quantitative pump such as a plunger pump is used for the hydraulic unit. It is difficult to exactly match the discharge oil amount of the two hydraulic units, and even if the discharge oil amounts can be completely matched, some leakage can be avoided in the hydraulic circuit It is impossible to completely match even this leak amount, and the tuning has not been assured.

Therefore, the most commonly used tuning system in recent years employs a system in which both lifts are mechanically connected by a connecting rod or the like. However, even if the two lifts are mechanically connected, there is no point in connecting the cylinders that are the outer cylinders of both lifts, and it is of course possible to mechanically connect the elevating parts such as the plunger. However, since the lifting part such as the plunger is normally inserted into the cylinder when the lift is lowered to the lowermost end, specifically, each loading platform fixed to the upper end of the lifting part such as the plunger is provided. Will be linked. However, when connecting the loading platforms, the connecting equipment blocks the bottom of the vehicle in the vehicle lift, which is inconvenient for inspection and maintenance of the vehicle. A method in which the lower ends of both vertical bars are suspended by a horizontal bar located below the floor surface, or a rack is suspended in place of the above vertical bars, and both racks have pinions fixed to a common shaft below the floor surface. And the like are employed.

[0008]

However, the mechanical connection system as the tuning mechanism also has a disadvantage that the connection mechanism must be made strong and the whole device becomes heavy. When the mechanism is made strong, accuracy such as verticality of a pair of lifts is required, manufacturing becomes complicated, and furthermore, when an eccentric load is applied, the connecting rods and the like flex and a force other than vertical is applied to the lift, Fatigue of lift seals,
There is a problem that breakage is promoted.

Further, since the above-mentioned tuning mechanism has not been developed for a two-stage hydraulic lift, if this tuning system is applied to a two-stage hydraulic lift, it is possible to install the cylinder within a limited burial depth by setting a short cylinder. However, there is also a problem that the depth of the storage space for the vertical bar or the rack is required to be long, and the two-stage type is not meaningful.

In view of the above, the present invention has been made to solve the above problems, and uses a pair of two-stage hydraulic lifts to ascend and descend precisely in synchronization without mechanically connecting the two two-stage hydraulic lifts. It is intended to provide a hydraulic lift.

[0011]

SUMMARY OF THE INVENTION In accordance with the above-mentioned object, the construction of the present invention, which has the features of the above-mentioned claims, is provided in a cylinder 11 having a lifting oil inlet / outlet 18 at a lower part. The piston 12 is accommodated therein. A cylindrical first plunger 14 having an upper end protruding from a first metal 13 disposed inside the upper end of the cylinder 11 is erected on the piston 12. A first stopper projection 15 protrudes from the outer peripheral surface, and a through hole 1 is provided in a portion of the peripheral surface of the first plunger 14 below the first stopper projection 15.
6, a two-stage type in which the second plunger 17 is housed in the first plunger 14 with its upper end protruding from the second metal 19 disposed at the upper end of the first plunger 14. Having a cylinder body 51 having a volume equal to or greater than the oil capacity required to raise both hydraulic lifts 10, 10 from the lowermost end to the uppermost end by embedding the hydraulic lift 10 below the pair of floor surfaces FL. And a hydraulic unit 70 for supplying drive oil to the lift equivalent discharge cylinder 50. The lift equal discharge cylinder 50 is configured such that the cylinder body 51 is separated into one chamber by a partition wall 53. A and a second chamber B, and one side piston 52a housed in the one chamber A in the cylinder body 1;
The other piston 52b is accommodated in the other chamber B, and a connecting rod 52c that connects the one piston 52a and the other piston 52b and slidably penetrates the partition wall 53 while keeping the partition 53 airtight. And the cross-sectional area of the one chamber A is set to the same value as the cross-sectional area of the connecting rod 52c subtracted from the cross-sectional area of the other chamber B. Oil outlets 54a and 54b communicating with the hydraulic unit 70 are provided between the piston lower chamber AD and the piston lower chamber BD of the other chamber B, respectively, and the piston upper chamber AU of the one chamber A and the piston upper chamber BU of the other chamber B respectively. The hydraulic lifts 10, 10 have technical means provided with oil discharge ports 55a, 55b communicating with the lifting oil ports 18, 18, respectively.

[0012]

Next, the operation of the present invention will be described. The upper chamber of the piston 12 in the cylinder 11 of each of the hydraulic lifts 10, 10 and the lower chamber of the piston 12 or the equivalent discharge cylinder 50 for the lift are used. Oil is tightly filled in the piston upper chambers AU and BU, and oil is also tightly filled in the piping from the piston lower chambers AD and BD to the hydraulic unit 70 of the lift equal discharge cylinder 50. Shall be

Therefore, when the hydraulic lifts 10, 10 are raised, the hydraulic unit 70 is operated to pump oil in the oil tank into the piston lower chambers AD, BD of the lift equal discharge cylinder 50. Then, the double piston 52
And the oil in the piston upper chambers AU, BU flows out from the oil discharge ports 55a, 55b by an equal amount, and is sent to the lower piston chambers of the hydraulic lifts 10, 10, and the pistons 12 of the hydraulic lifts 10, 10 are compressed. Or the first plunger 1
4 is pushed up. When the piston 12 is pushed up, the volume in the upper chamber of the piston of the cylinder 11 decreases accordingly, so that the oil in the upper chamber of the piston flows into the first plunger 14 through the through hole 16 and simultaneously pushes the second plunger 17. I will give it.

When the hydraulic lifts 10, 10 are lowered, the operation of the hydraulic unit 70 is stopped, and the oil ports 54a, 54b and the oil tank of the hydraulic unit 70 are brought into a conductive state (a state in which oil can pass freely). ). Then, the double piston 2 of the lift equal discharge cylinder 50 descends by its own weight, and the oil in the piston lower chambers AD and BD returns to the oil tank side.
The pistons 0 to 10 and the first plunger 14 also descend by their own weights, and the oil in the lower chambers of both pistons 12 returns to the upper piston chambers AU and BU of the equal discharge cylinder 50 for lift. Then, the lowering of both pistons 12 increases the volume of the upper chamber of the pistons, so that the second plungers 17 also lower their own weights and return to the initial state.

The cross-sectional area of the one chamber A of the equal-discharge cylinder for lift 50 is determined by the cross-sectional area of the other chamber B.
Since it is set to the same value as the value obtained by subtracting the cross-sectional area of c,
One-way chamber A that changes by the movement of the dual piston 52
Piston upper chamber AU of the other chamber and piston upper chamber BU of the other chamber B
And the change in volume is always the same.
The oil entering and exiting from a and 54b exhibits an equal action.

Further, both hydraulic lifts 10 include a piston 12
Is raised, the second plunger 17 is also raised at the same time. Therefore, the first plunger 14 and the second plunger 17 do not rise and fall unrelatedly. In other words, the first plunger 14 Second plunger 17
Of the second plunger 17 is not equal to the piston 1
The function of raising and lowering the two hydraulic lifts is ensured in proportion to the amount of oil in the lower chamber 2.

[0017]

In the drawing, reference numeral 10 denotes a two-stage hydraulic lift. This hydraulic lift 10 accommodates a piston 12 in a cylinder 11 having a lifting oil inlet / outlet 18 at a lower portion. A first cylindrical plunger 14 protruding from the first metal 13 disposed in the upper end of the cylinder 11 is erected, and a first stopper projection 15 is protruded from a lower outer peripheral surface of the first plunger 14, A through hole 1 is provided on the peripheral surface of the first plunger 14 below the first stopper projection 15.
6, and the second plunger 17 is housed in the first plunger 14 with its upper end protruding from the second metal 19 disposed at the upper end of the first plunger 14.

As the hydraulic lift 10, one as shown in FIG. 1 or FIG. 2 is used.
1 has a bottom 11a, and a lifting oil port 18 at the bottom.
A hydraulic unit 70 to be described later is connected to the elevating oil port 18. The cylinder 11
The flange portion 13a of the first metal 13 is placed on the upper flange 11b portion, and both are fastened by fixing screws 20. The first metal 13 is provided with a packing 21, a scraper 22, and the like. This is the same as a conventionally known lift metal.

A conventionally known piston 12 is used. A first plunger 14 is erected on the upper surface of the piston 12 by means of welding or the like, and the first stopper projection 15 and the through hole 16 are connected to each other. Provided. In this embodiment, the through hole 16 is provided so as to communicate from the outer surface of the first stopper projection 15 to the inner surface of the first plunger 14,
Immediately above the first stopper projection 15, an air vent hole 23 communicating with the inner surface of the first plunger 14 is formed.

The air vent hole 23 is provided in the first plunger 1.
In order to prevent the air mixed with the oil from accumulating in the upper portion of the fourth plunger 4, the air vent valve 40 is provided in the lid 24 of the second plunger 17 in this embodiment. 2)) through the first plunger 14
It is designed to move inside.

As the air vent valve 40, a conventionally known one is used. Usually, an opening is closed by a closing screw 41, and when the air is vented, a conventionally known valve that removes the closing screw 41 is used. used.

The second metal 19 is shown in FIG.
In the example, a metal having the same structure as the first metal 13 is disposed inside the first plunger 14, but in the example of FIG. The inner diameter of the metal 19 is configured to be substantially the same as the inner diameter of the first plunger 14, and the outer diameter thereof is configured to match the outer diameter of the first plunger 14. is there.

The second metal 19 in the example shown in FIG. 2 includes a main body 19a and a foot 19b connected downward from the main body 19a. A vertical distance is set to be large by penetrating into the circumferentially enlarged portion, and a large external force (force for tilting the second plunger 17 due to an unbalanced load) by the second plunger 17 described below is supported at two points above and below the second metal 19. Although the strength is improved, it is a matter of course that the feet 19b may be omitted if the strength is satisfied. The second metal 1
9, the inner diameter of which is substantially the same as the inner diameter of the first plunger 14, the inner surface of the first plunger 14 and the second metal 19
The inner diameter of the second metal 19 is set so that the outer peripheral surface of the second plunger 17 described below does not actually contact the inner surface of the first plunger 14.
The outer diameter of the second metal 19 is slightly smaller than the inner diameter of the first plunger 14.
4 so as to match the outer diameter of the first plunger 14.
It is a matter of course that the second metal 19 is fixed coaxially on the extension of the outer peripheral surface so that the outer peripheral surface of the second metal 19 coincides with the outer peripheral surface of the second metal 19 so that the second metal 19 can move up and down in the first metal 13 while maintaining the airtightness.

In the example shown in FIG. 1, the second plunger 17 has a second stopper projection 25a projecting outward at the lower end thereof. In the example shown in FIG. Since there is no space between the second plunger 17 and the second plunger 17 for projecting the second stopper projection 25a, the second plunger 17 is formed in a bottom-opened cylindrical shape in which the lid 24 is detachably disposed, and the bottom of the second plunger 17 is formed at the bottom. A second stopper projection 25 protruding inward is fixed.

The lid 24 is fastened to the second plunger 17 with a fixing screw 26. In the illustrated example, the lid receiver 27 is welded to the upper end of the second plunger 17. 27 is because the thickness of the second plunger 17 is not sufficient to provide a screw hole for the fixing screw 26, and a large machine tool is required to provide a screw hole at the upper end of the long second plunger 17; The lid receiver 27 may be omitted, and the lid 24 may be directly screwed to the upper end of the second plunger 17.

Further, in the example shown in FIG. 2, a rod 28 whose upper end is inserted into the second plunger 17 is erected at the center of the piston 12, and the upper end of the rod 28 has an enlarged diameter stopper receiver. 29 are detachably connected.
It is needless to say that the rod 28 is configured to have a smaller diameter than the inner diameter of the second plunger 17. The rod 28 may be erected on the piston 12 by appropriate means. In the illustrated example, a through hole 32 is formed at the center of the piston 12. A flange 28a is provided at the lower end of the rod 28, the rod 28 is inserted into the through hole 32 from the lower surface side of the piston 12, and the flange 28a is fixed with a fixing screw 30.
To stand upright on the lower surface of the piston 12.

A thread 31 is provided at the upper end of the rod 28.
The diameter-enlarged stopper receiver 29 is screwed onto the thread 31 and detachably connected thereto. Further, a screw 33 is screwed onto the rod 28 to screw the diameter-enlarged stopper receiver 29 into engagement. To prevent loosening. It is a matter of course that the second stopper projection 25 comes into contact with the lower surface of the enlarged diameter stopper receiver 29.

In the illustrated embodiment, the piston 12
A valve 34 is provided for communicating the valve upper chamber A and the valve lower chamber B when the piston 12 descends to the lower end. This valve 34
Is the same in structure and the purpose of use as the valve 63 of the equal-discharge cylinder for lift 50 described later, and the description thereof is omitted here.

In FIG. 2, reference numeral 35 denotes a packing, 36 denotes a scraper, and 37 denotes a piston seal ring.

A pair of the hydraulic lifts 10 are buried under the floor surface FL.

An equal-discharge cylinder 50 for lift having a cylinder body 51 having a volume equal to or greater than the oil capacity required to raise the hydraulic lifts 10, 10 from the lowermost end to the uppermost end; Equivalent discharge cylinder 50
And a hydraulic unit 70 for supplying the drive oil is separately provided.

In the lift equal discharge cylinder 50, the cylinder body 51 is partitioned into one chamber A and the other chamber B by a partition wall 53. In the cylinder body 1, one side piston housed in the one chamber A is provided. 52a, the other piston 52b housed in the other chamber B, and the one piston 52a
And the other side piston 52b.
3 is connected to the connecting rod 52c slidably and slidably inserted therein, and the cross-sectional area of the one chamber A is made larger than the cross-sectional area of the other chamber B. Oil outlets 54a and 54b communicating with the hydraulic unit 70 are connected to the piston lower chamber AD of the one chamber A and the piston lower chamber BD of the other chamber B, respectively. A hydraulic lift 1 is provided between the piston upper chamber AU of A and the piston upper chamber BU of the other chamber B.
Oil discharge ports 55a and 55b are provided to communicate with the lifting oil inlets and outlets 0 and 10 respectively.

In the present embodiment, the lift equal discharge cylinder 50 is the one shown most clearly in FIG. 3 and thereafter, and the cylinder body 51 is a hydraulic lift 1
Using a buried type lift at 0, 10
Adopts a method in which the cylinder body 51 is buried between the two hydraulic lifts 10, and the cylinder body 51 is set at the same height as the cylinder 11 of the hydraulic lift 10 so as to efficiently use the storage space. The capacity of the cylinder body 51 may be set to a predetermined value depending on the inner diameter and the height. When the cylinder body 51 is installed on the floor, the diameter may be increased and the height may be reduced. The cylinder body 51 is installed vertically in the illustrated example, and the double piston 52 is caused to return by its own weight. However, the double piston 52 is moved backward by incorporating a spring or the like. If it is performed by the urging force of a spring or the like, it can be installed in the horizontal direction.

Then, the cylinder body 51 is separated from the partition wall 53.
Divides into one room A and the other room B. It is most desirable that the partition wall 53 partition both volumes of the one chamber A and the other chamber B substantially the same. It is needless to say that the partition wall 53 is disposed substantially at the center in the upper and lower directions. However, in this embodiment, in order to facilitate maintenance and inspection, it is housed detachably from above.

That is, the partition wall 53 is formed as a cylindrical body having a seal ring 59 disposed on the peripheral surface, and the inner cylinder 56 is erected on the upper surface of the partition wall 53 by means such as welding (see FIG. 4). The upper end flange portion 56a of the inner cylinder 56 is placed on the upper end opening flange portion 51a of the cylinder main body 51 so that it can be extracted together with the inner cylinder 56 above the cylinder main body 51. It is.

In the cylinder body 51, a one-side piston 52a housed in the one-sided chamber A, another side piston 52b housed in the other-sided chamber B, the one-side piston 52a and the other-side piston 52b, and a connecting piston 52c, which is slidably inserted through the partition wall 53 while maintaining airtightness, is housed therein.

As shown in FIG. 5, the double piston 52 is housed through a central through hole 57 of a partition wall 53, and a seal ring 58 is provided on the inner peripheral surface of the central through hole 57. The one-side piston 52a has a seal ring 59 on its outer peripheral surface and is in contact with the inner peripheral surface of the inner cylinder 56, and the other-side piston 52b has a seal ring 60 on its outer peripheral surface and It is a matter of course that the diameter of the one-side piston 52a and the other-side piston 52b is larger than the center through hole 57. In the illustrated example, a connecting rod 52c is erected on the lower piston 52b by means of welding or the like as shown in FIG. 4, and one end is connected to the upper end of the connecting rod 52c. Piston 5
2a is fixed with fixing screws 61 (see FIG. 5).
Note that, since the one-side piston 52a is housed in the inner cylinder 56, the one chamber A is not exactly the entire upper part of the partition 53 inside the cylinder body 51, but the inside of the inner cylinder 56 It means the upper part.

In this embodiment, a valve 63 for communicating the lower piston chamber AD and the upper piston chamber AU when the one piston 52a is lowered to the lowermost end is provided on the one piston 52a. A valve 6 for communicating the lower piston chamber BD with the upper piston chamber BU when the other piston 52b descends to the lowermost end.
3 is provided.

This valve 63 (the one provided on one side piston 52a and the other side piston 52b has the same structure,
The description will be made on the one provided on the one-side piston 52a side shown in FIG. 5 and FIG. ), A valve body 66 urged downward by a spring 65 is disposed above a valve seat 64 (on the piston upper chamber AU side) provided between the piston upper chamber AU and the piston lower chamber AD. When the one-side piston 52a is lowered to the lowermost end, the lower end of the one-side piston 52a contacts the partition wall 53 (or the bottom 51b of the cylinder body 51) and the valve body 66
Is lifted against the urging force of the spring 65, and the valve operating rod 67 is suspended.
D enters.

The valve 63 is used to inject oil into the upper piston chambers AU and BU when the device of the present invention is installed, and to reduce the oil volume in the upper piston chambers AU and BU due to leakage or thermal expansion during use. Is used to correct this when it changes.

That is, in the state of FIG. 1, it is assumed that oil has not been supplied to the upstream side of the hydraulic unit 70 yet. Then, the hydraulic unit 70 is operated in this state,
When the oil is pumped to the downstream side, the valves 63, 63 become "Fig. 4".
Although it is open as shown in FIG. 5, the diameter of this communication hole is small, so that the double piston 52a rises, and when the double piston 52a rises to the uppermost end and the oil is fed again, the pressure difference is caused by the pressure difference. 63, 63 are opened, and oil is also injected into the piston upper chambers AU, BU. Further, the oil also flows into the two hydraulic lifts 10, 10, and when the first plungers 14 of the hydraulic lift 10 rise to the uppermost ends, the valve 34 is also opened, and the oil also flows into the first plungers 14. I do.

Then, when the oil is tightly filled into both the first plungers 14 and the oil is further pressure-fed to the piston lower chambers AD and BD, the oil pushes up the dual piston 52 and the valves 63 and 63 close. When the dual piston 52a rises, the volume of the piston upper chambers AU, BU decreases accordingly, and the oil in the piston upper chambers AU, BU flows out of the oil discharge ports 55a, 55b of the cylinder body 51. When the dual piston 52 starts to rise, the valves 63, 63 are open, so the piston upper chambers AU, BU
If one or both of the oils are insufficient, first, oil is replenished into the piston upper chambers AU and BU.

When the dual piston 52 is lowered, the operation of the hydraulic unit 70 is stopped, and the oil ports 54a, 54b and the oil tank of the hydraulic unit 70 are brought into conduction. Then, the dual piston 52 descends by its own weight (moves by the urging force of a spring or the like in the case of a horizontal type not shown), and the oil in the piston lower chambers AD and BD returns to the oil tank. Rooms AU, B
Either one or both oils in U may be expanding. Therefore, in this embodiment, when the dual piston 52 is lowered to the lowermost end, the valves 63, 63 are pushed up and opened by the valve operating rod 67, and the oil corresponding to the expanded volume is supplied to the valve 6.
It flows out to the oil tank side through 3, 63.

In the illustrated example, the one-side piston 52a
In order to prevent air from accumulating on the lower surface of the valve seat 64, the through hole 68 communicating with the lower portion of the valve seat 64 is appropriately bent as shown most clearly in FIG. 6 and its tip is one-side piston 52a (the other-side piston 52b). Also the same).

The sectional area of the one chamber A is set to be equal to a value obtained by subtracting the sectional area of the connecting rod 52c from the sectional area of the other chamber B. That is, by setting the cross-sectional area of the one chamber A and the cross-sectional area of the other chamber B in this manner, it becomes possible to discharge an equal amount of oil by the movement of the dual piston 52. However, setting the cross section in this way,
Since the diameter of the upper one chamber A becomes smaller than the diameter of the lower other piston 52b, and the other piston 52b cannot be stored and removed from above the cylinder body 51,
In this embodiment, the inner cylinder 56 is used to reduce the diameter of the upper one chamber A, and the inside of the inner cylinder 56 is used as the one chamber A.

Then, the piston lower chamber A of the one chamber A
D and the piston lower chamber BD of the other chamber B are provided with oil ports 54a, 54b communicating with the hydraulic unit 70, the piston upper chamber AU of the one chamber A and the piston upper chamber B of the other chamber B.
U is provided with oil discharge ports 55a, 55b communicating with the hydraulic lifts 10, 10, respectively.

The oil inlets and outlets 54a and 54b may be separately provided in the lower piston chambers AD and BD of the cylinder body 51. In the illustrated embodiment, the oil inlets and outlets 54b and 54b are provided only in the lower piston chamber BD of the other chamber B. And the other oil inlet / outlet 54a uses a through hole that opens from the lower surface of the other piston 52b to the inside of the connecting rod 52c and below the one piston 52a (inside the one chamber A).

As shown in FIGS. 1 and 3, the oil discharge ports 55a and 55b are connected to the piston lower chambers AU and 55, respectively.
The inner tube 56 may be provided in the upper part of the BU. However, since the inner cylinder 56 is actually provided in the one chamber A, as shown in FIG. A hole 56b is provided, and the space between the inner surface of the cylinder body 51 and the outer surface of the inner cylinder 56 is used for an oil flow path.

The oil outlets 54a, 54b
The discharge port of the hydraulic unit 70 is connected to the oil inlet / outlet 54b in this embodiment by a pipe. As the hydraulic unit 70, a conventionally known hydraulic unit can be used. In the illustrated example, an oil tank 71, a pump 72, a motor 73, a check valve 74
A return valve 75 is provided in the middle of the return pipe 75. The switching valve 76 normally interrupts the return path with a check valve or the like and conducts the return path to the oil tank 71 when power is supplied. When the oil inlets and outlets 54a and 54b are separately provided in the cylinder main body 51, instead of using two hydraulic units 70, the downstream side of the oil pressure feeding pipe 77 of one hydraulic unit 70 is branched and respectively. Shall be linked to

In FIG. 3, reference numeral 69 denotes a strainer net.

[0051]

According to the present invention, the same hydraulic discharge cylinder 50 is interposed between the hydraulic unit 70 and the hydraulic lifts 10 and 10 so that both hydraulic lifts 1 are provided.
The amount of oil supplied and returned to 0 and 10 can always be equalized. This oil equalization is, of course, for synchronizing the elevation of the pair of lifts. However, in a two-stage hydraulic lift alone, perfect synchronization cannot be realized. That is, the two-stage hydraulic lift has a difference in the rising speed between the case where the large-diameter first plunger 14 rises and the case where the small-diameter second plunger rises even if the same amount of oil is pumped. It is because they have. Therefore, in the present invention, the hydraulic lift uses a system in which the volume of the upper chamber of the piston 12 is reduced by raising the piston 12, and the oil filled in the upper chamber pushes up the second plunger 17. As a result, the lifting distance of the second plunger 17 is reliably determined by the amount of oil supplied to the hydraulic lift 10, and a hydraulic lift capable of completely lifting and lowering the pair of two-stage hydraulic lifts 10, 10 in synchronization with each other. That can be provided.

Further, according to the present invention, since the synchronization is not performed at the mechanical connection portion, the mechanical parts which move up and down with the lifting and lowering of the lift can be minimized, and the maintenance and inspection are performed by raising the vehicle. It is possible to provide a hydraulic lift capable of omitting an object that hinders an operation in a state where a heavy object is lifted.

Further, the present invention provides both hydraulic lifts 10 and 10
When an eccentric load is applied to the
Appears as a difference between the pressure applied to the upper surface of the one-side piston 52a and the pressure applied to the upper surface of the other-side piston 52b. Since this force is in the axial direction of the lift equivalent discharge cylinder 50, It is possible to provide a hydraulic lift excellent in durability, in which an external force other than the axial direction, which is regarded as a major weak point, is hardly applied.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the hydraulic lift of the present invention.

FIG. 2 is a half sectional view showing another embodiment of the hydraulic lift body used in the present invention.

FIG. 3 is a sectional view of a lift equalizing discharge cylinder used in the present invention.

FIG. 4 is a detailed cross-sectional view of a lower portion of the equal discharge cylinder for lift used in the present invention.

FIG. 5 is a detailed sectional view of the middle part of the equal discharge cylinder for lift used in the present invention.

FIG. 6 is a detailed sectional view of a valve portion used in the present invention.

[Explanation of symbols]

 Reference Signs List 10 Hydraulic lift 11 Cylinder 12 Piston 13 First metal 14 First plunger 15 First stopper projection 16 Through hole 17 Second plunger 18 Elevating oil port 19 Second metal 50 Equivalent discharge cylinder for lift 51 Cylinder body 52a One side piston 52b Other piston 52c Connecting rod 53 Partition wall 54a Oil port 54b Oil port 55a Oil discharge port 55b Oil discharge port 70 Hydraulic unit A One chamber AD Piston lower chamber AU Piston upper chamber B Other chamber BD Piston lower chamber BU Piston upper chamber FL Floor surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model 1-166700 (JP, U) Japanese Utility Model 56-103600 (JP, U) Japanese Utility Model 2 135585 (JP, U) Japanese Utility Model 3 95392 (JP, U) West German Patent Application Publication 3420808 (DE, A1) British Patent Application Publication 1458350 (GB, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B66F 7/20 B66F 7 / 28

Claims (1)

(57) [Claims] 1. A piston (12) is housed in a cylinder (11) having a lifting oil inlet / outlet (18) at a lower portion, and an upper end of the piston (12) is disposed in an upper end of the cylinder (11). A first cylindrical plunger (14) protruding from the first metal (13) thus formed, and a first stopper projection (15) protruding from a lower outer peripheral surface of the first plunger (14); A through hole (16) is formed in a portion of the peripheral surface of the first plunger (14) below the first stopper projection (15), and a second plunger (17) is formed in the first plunger (14). ) With the upper end of the first plunger (14).
A two-stage hydraulic lift (10), which is protruded from the second metal (19) disposed at the upper end of the hydraulic lift (10), is buried under the pair of floors (FL). 10) A lift equal-discharge cylinder (50) having a cylinder body (51) having a volume equal to or greater than the oil capacity necessary to ascend the lower end from the lowermost end to the uppermost end; 50), a hydraulic unit (70) for supplying drive oil is separately provided. In the lift equal-discharge cylinder (50), the cylinder body (51) is divided into one chamber (A) and the other chamber by a partition (53). (B), and inside the cylinder body (51),
One side piston (52a) housed in one room (A)
And the other piston (52) housed in the other chamber (B).
b) and a connecting rod (52c) which connects the one-side piston (52a) and the other-side piston (52b) and slidably penetrates the partition wall (53) while maintaining airtightness. The connecting piston (52) is housed, and the sectional area of the one chamber (A) is set to the same value as the sectional area of the connecting rod (52c) subtracted from the sectional area of the other chamber (B). An oil port (54a, 54b) communicating with a hydraulic unit (70) is provided between the lower piston chamber (AD) of the one chamber (A) and the lower piston chamber (BD) of the other chamber (B).
In the upper chamber (AU) of the first chamber (A) and the upper chamber (BU) of the other chamber (B), the respective hydraulic oil lifts (10, 10) have respective lifting oil inlets (18, 1).
8) A hydraulic lift provided with oil discharge ports (55a, 55b) communicating with the hydraulic lift.