JPH08177809A - Locking structure for vertical movement body of hydraulic cylinder - Google Patents

Abstract

PURPOSE: To dispense with a security device on the outside by stopping an elevating body of a hydraulic cylinder at an optional position, and thereby preventing a piston and an inner cylinder housing from lowering even in the case that hydraulic pressure in a first hydraulic chamber is reduced because of leakage from a cylinder packaging or breakage of a hydraulic hose on the side of a first oil inlet. CONSTITUTION: Oil in an A port is introduced into a first hydraulic chamber 22 of a hydraulic cylinder 1, and a piston 11 is elevated while being guided by a guide rod 13. An inner cylinder housing 16 integrated with the piston 11 is elevated while being guided by an upper wall 7 of an outer cylinder housing 2. Simultaneously, oil in the first hydraulic chamber 22 is press-fed to a lock hydraulic chamber 19 through a first flow passage 26 of the piston, a passage having an opened check valve, and a second flow passage 29 of the piston. When oil supply is stopped, the piston 11 and the inner cylinder housing 16 are stopped at optional positions. Oil in the lock hydraulic chamber 19 is prevented from flowing to the first hydraulic chamber 22 by means of a check valve 25. The piston 11 is not lowered even in the case that sealability of an outer packing 37 is lowered or a first hose 23 is broken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock structure for a lifting body of a hydraulic cylinder. INDUSTRIAL APPLICABILITY The present invention can be used in the fields of industrial use of hydraulic cylinders, for example, industrial robots, maintenance lifts for vehicles, vehicles having lifts for unloading and wheelchairs, vehicles for electrical work, furniture and electrical equipment, etc. is there.

[0002]

2. Description of the Related Art An example of a conventional hydraulic cylinder mechanism is described in Japanese Utility Model Laid-Open No. 57-77706.

In this embodiment, as shown in FIG. 7, a cylinder housing 101 having a pair of side walls 102 and 103.
And the piston 104 fitted in this cylinder housing
And a piston rod 10 which is connected to the piston and projects outward through one side wall 102 of the housing.
5 and a pair of oil inlets and outlets 108 and 109 provided on both sides of the housing with the piston 104 interposed therebetween, the piston 104 and the piston rod 105 are hollow, and the other side of the housing The cross-sectional area compensating rod 111 arranged on the side wall 103 of the piston is attached to the hollow portion 11 of the piston 104 and the piston rod 105.
It is characterized by being fitted to 0.

However, in the above-mentioned hydraulic cylinder mechanism, when the hydraulic cylinder 100 is disposed in the vertical direction and used for a vehicle maintenance lift, for example, there are the following problems.

That is, when the packing 113 provided on the outer peripheral wall of the piston 104 which is in sliding contact with the inner peripheral wall of the cylinder housing 101 is worn and oil leaks, the piston 104 descends naturally (slowly). When the hydraulic hose 114 on the downstream side is damaged due to electrolytic corrosion or the like, the piston 104 rapidly descends.

Therefore, the hydraulic cylinder 10 having the above structure
No. 0 must be equipped with a safety device for preventing the piston 104 from descending. In general, however, the safety device is "provided outside the hydraulic cylinder as described in Japanese Utility Model Laid-Open No. 138000/1989. "A combination of a rack and a locking claw" or "a combination of an engaging plate having a plurality of engaging holes provided outside the hydraulic cylinder and a locking pin as a safety rod".

However, since most safety devices mounted on hydraulic cylinders are mounted or arranged outside the hydraulic cylinders, not only the maintenance work space is reduced accordingly, but sometimes incidental equipment (for example, a rack or a staff). Water and earth and sand could get into the sheath that holds the plywood and cause malfunctions.

Therefore, it is required to introduce a safety device (lowering means for lowering and lowering the lifting body) that eliminates the above drawbacks in the hydraulic cylinder.

[0009]

In view of the above conventional requirements, the present invention eliminates the need for mounting or disposing a safety device on the outside of the hydraulic cylinder, thus ensuring a sufficient external space of the hydraulic cylinder. In addition, the lifting / lowering body of the hydraulic cylinder can be immediately stopped at an arbitrary position, and further, when the lifting / lowering body of the hydraulic cylinder is stopped at an arbitrary position, a leak from the cylinder packing ( Even if the hydraulic pressure in the first hydraulic chamber decreases due to leakage) or damage to the hydraulic hose on the first oil inlet / outlet (driving) side, the piston as an elevating body and the inner cylinder housing do not descend. Is to get.

[0010]

A lock structure for a lifting body of a hydraulic cylinder according to the present invention is slidably fitted in an outer cylinder housing 2 of a hydraulic cylinder 1 and fixed to an inner wall of a lower wall portion 5. A piston 11 slidably fitted to a vertically installed guide rod 13, and an opening 8 in an upper wall portion 7 of the hydraulic cylinder 1.
An inner cylinder housing 16 that is slidably fitted into the outer cylinder housing 2 via a lower end 16a and is fixedly provided on the upper surface 11a of the piston 11;
And a lock hydraulic chamber 19 formed relatively between the inner wall of the inner cylinder housing 16 and the outer wall of the guide rod 13 on the lower surface 11b side of the piston, and the outer cylinder housing 2. Oil circulation holes 27 that communicate with the second hydraulic chambers 17 formed between the inner cylinder housing 16 and
Check valve 25 having 30, 36.

[0011]

In the check valve, when the piston rises, the oil pressure-fed to the first hydraulic chamber flows from the first hydraulic chamber to the lock hydraulic chamber through the first flow passage and the second flow passage formed in the piston. Flowing. In this case, when the piston and the inner cylinder housing rise, the guide rod comes out of the inner cylinder housing, so that the capacity (volume) of the inner cylinder housing gradually increases following the rise of the elevating body.

Next, when the drive motor is stopped, the piston immediately stops at an arbitrary position. When the piston stops,
The lock oil filling the lock hydraulic chamber does not flow in the opposite direction and loses its escape. Therefore, even if the hydraulic pressure in the first hydraulic chamber decreases due to leakage from the outer packing of the piston or damage to the hydraulic hose on the first oil inlet / outlet side, the piston as the lifting body and the inner cylinder housing do not descend.

On the other hand, when the piston descends, the oil pressure-fed to the second hydraulic chamber opens the valve through the third flow path formed in the piston to guide the lock oil filled in the lock hydraulic chamber. While the rod enters the inner cylinder housing,
Pour into hydraulic chamber. Therefore, the lifting body descends.

[0014]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

In one embodiment shown in FIGS. 1 to 6,
Reference numeral 1 is a hydraulic cylinder having a lock structure or a lock mechanism for the lifting body (piston and inner cylinder housing). This hydraulic cylinder 1 stops an inner cylinder housing in a sliding relationship with a piston that moves up and down in the cylinder using a hydraulic mechanism and an outer cylinder housing (hereinafter referred to as an outer cylinder housing) at an arbitrary position. Let it lock. That is, the hydraulic cylinder 1 is locked by the lock oil in the lock hydraulic chamber when the ascending / descending piston stops at an arbitrary position, and temporarily leaks from the cylinder packing or the hydraulic pressure on the first oil inlet / outlet (drive) side. Even if the hydraulic pressure in the first hydraulic chamber decreases due to the hose breakage, the piston as the lifting body and the inner cylinder housing do not descend.

Therefore, the hydraulic cylinder 1 will be described first with reference to FIG. Reference numeral 2 denotes an outer cylinder housing of the hydraulic cylinder 1. The lower end portion of the outer cylinder housing 2 has a first drive side member.
An oil inlet / outlet 3 is formed, and on the other hand, a second oil inlet / outlet 4 is formed at the upper end portion thereof. Reference numeral 5 denotes a lower wall portion 5 of the hydraulic cylinder 1, and a plate-shaped piston receiving portion 6 is appropriately provided on the inner wall of the lower wall portion 5 so as to project. On the other hand, 7 is an upper wall portion of the hydraulic cylinder 1, and an opening 8 is formed in this upper wall portion 7. The upper wall portion 7 has a flange 9 and is fixed to the flange 2 a of the outer cylinder housing 2 via a fixing tool 10.

Next, reference numeral 11 is a through hole formed in a guide rod 13 which is slidably fitted in the outer cylinder housing 2 of the hydraulic cylinder 1 and which is fixedly erected at the center of the inner wall of the lower wall portion 5. It is a piston slidably fitted through 14. In this embodiment, only one guide rod 13 is provided in the central portion of the inner wall of the lower wall portion 5 via a fastener 15 in order to balance the piston 11. Of course, if the piston 11 can be balanced, a plurality of through holes 14 may be formed in the piston 11 and a plurality of guide rods 13 may be provided in correspondence with the number of these through holes 14. The length of the guide rod 13 is determined in consideration of the vertical position of the piston 11. In this embodiment, it extends into the upper wall portion 7.

Next, 16 is slidably inserted into the outer cylinder housing 2 through the opening 8 of the upper wall portion 7 of the hydraulic cylinder 1, and the lower end portion is fixedly provided to the piston 11. It is a cylinder housing. The lower end portion 16a on the opening side of the inner cylinder housing 16 is fixed to a peripheral wall (projection) portion provided around the upper surface 11a of the piston 11 in a stepwise manner, while the upper end portion 16b of the inner cylinder housing 16 is fixed to the outer cylinder housing 2 It slightly protrudes from the upper wall portion 7. A support plate (support arm) that supports the underfloor of the vehicle is fixedly attached to the upper end 16b of the inner cylinder housing 16, for example, in the case of a vehicle maintenance lift that is an example of the invention of use.

A second hydraulic chamber 17 communicating with the second oil inlet / outlet 4 is formed between the outer cylinder housing 2 and the inner cylinder housing 16, and the outer wall (outer circumference) of the inner cylinder housing 16 and the guide rod 13 is formed. A lock hydraulic chamber 19 having a lock oil 18 is relatively formed between the wall and the wall. A lock upper wall portion 20 forming a part of a lock hydraulic chamber is hermetically fitted to an upper end portion 16b of the inner cylinder housing 16, and an air vent valve 21 is provided in a central portion of the lock upper wall portion 20. It is provided.

Next, 22 is a first hydraulic chamber formed between the lower wall portion 5 of the hydraulic cylinder 1 and the lower surface 11b of the piston 11 which moves up and down. The first hydraulic chamber 22 is the first oil inlet / outlet port 3
Communicate with The first hydraulic chamber 22 and the first oil inlet / outlet 3 correspond to the drive side when the piston 11 is raised. Therefore, the first hose 23 is connected to the first oil inlet / outlet 3, and the second hose 24 is connected to the second oil inlet / outlet 4 described above.

Next, 25 is provided on the piston 11, and when the piston 11 rises, the oil pumped from the first hose 23 flows from the first hydraulic chamber 22 to the lock hydraulic chamber 19, but the piston is at an arbitrary position. When the piston 11 is stopped, the oil does not flow in the opposite direction. On the other hand, when the hydraulic pressure of the second hydraulic chamber 17 rises when the piston 11 descends, the lock oil 1 of the lock hydraulic chamber 19
8 is a check valve for flowing 8 into the first hydraulic chamber 22. As an example of the check valve 25, a pilot check valve is used as shown in FIGS. 2 and 3. This check valve 25 is assembled or attached to the piston 11 by appropriately working the piston 11. A plurality of suitable oil passages are formed in the piston.

That is, reference numeral 26 is a first flow passage connecting the first circulation hole 27 of the check valve 25 and the first hydraulic chamber 22 of the hydraulic cylinder 1 corresponding to the primary side. It is formed from the lower surface 11b side toward the first circulation hole 27. Check valve 25 1st circulation hole 27
Are provided in a direction intersecting the annular groove 28 in the circumferential direction.

Next, 29 is a plurality of second check valves 25.
A second flow path that connects the flow hole 30 and the lock hydraulic chamber 19 of the hydraulic cylinder 1 corresponding to the secondary side. The second flow path 29 is formed from the upper surface 11a of the piston 11 toward the second flow hole 30. Has been done. First circulation hole 27 of check valve 25
A valve 32, which constantly closes the oil passage by the spring force of the spring member 31, is interposed between and the second circulation hole 30.

Next, 34 is a valve pressing body having a piston function of the check valve 25. The valve pressing body 34 is composed of a piston portion 34a and a bar-shaped pressing portion 34b extending from the piston portion toward the valve 32. .

Next, 35 is the third through hole 3 of the check valve 25.
6 and the second hydraulic chamber 17 of the hydraulic cylinder 1 corresponding to the pilot pressure side, which is a third flow passage 35. This third flow passage 35 is located outside the upper surface 11a of the piston 11 (to be exact, the inner cylinder housing 16). Is formed toward the third circulation hole 36 from a portion outside the fixed position of the lower end portion 16a).

Next, the hydraulic cylinder 1 is appropriately provided with a plurality of packings, and 37 is an outer cylinder housing 2 in particular.
Is an outer packing provided on the outer peripheral wall of the piston 11 that is in sliding contact with the inner peripheral wall of the piston 11, while 38 is an inner packing provided on the inner peripheral wall of the piston 11 that is in sliding contact with the guide rod 13.

Next, the operation of the present invention will be described with reference to a general hydraulic circuit diagram using hydraulic symbols shown in FIG. In addition, in FIG.
0 is an oil tank, 41 is a drive motor, 42 is a hydraulic pump,
Reference numeral 43 is a direction control valve for switching the direction of oil, and 44 is a check valve.

First, the lifting body of the hydraulic cylinder 1 (piston 1
1 and the inner cylinder housing 16) are raised, the drive motor 41 is rotated and the oil tank 4 is driven by the hydraulic pump 42.
Pump oil from 0. The directional control valve 43 switches the oil to flow to the A port. The oil flowing to the A port is
It enters the first hydraulic chamber 22 of the hydraulic cylinder 1 via the first hose 23 and the first oil inlet / outlet 3. Therefore, the first hydraulic chamber 2
The oil in 2 pushes up the piston 11. Then, the piston 11 moves up while being guided by the guide rod 13. At this time, the inner cylinder housing 16 which is integral with the piston 11 is vertically guided while being guided by the upper wall portion 7 of the outer cylinder housing 2.

Then, as shown in FIG.
When the inner cylinder housing 16 rises, the guide rod 13
Is removed from the inner cylinder housing 16, so that the capacity (volume) of the inner cylinder housing 16 gradually increases following the rise of the lifting bodies 11 and 16, and at the same time, the oil in the first hydraulic chamber 22 Pass the first passage 26 of the piston, then the open passage of the check valve 25 and the second passage 2 of the piston
After passing through 9, the pressure is fed to the lock hydraulic chamber 19.

Therefore, when the drive motor 41 is arbitrarily stopped while the lifting bodies 11 and 16 are being raised, the piston 11 and the inner cylinder housing 16 are stopped at arbitrary positions as they are. In this case, normally, due to the check valve 25, the lock oil 18 in the lock hydraulic chamber 19 does not flow to the first hydraulic chamber 22 side.

By the way, it is assumed that the sealing property of the outer packing 37 is lowered for some reason or the first hose 23 on the drive side is damaged. In such a situation, the piston of the general hydraulic cylinder naturally descends or falls, but in the hydraulic cylinder 1 of this embodiment, the lock oil 18 in the lock hydraulic chamber 19 keeps the lock oil 18 in the inner cylinder housing 16 even if the piston 11 goes down. Since it is sealed inside and there is no so-called escape area, it does not descend.

Next, when lowering the lifting bodies 11 and 16 of the hydraulic cylinder 1, the drive motor 41 is rotated again and the hydraulic pump 42 pumps the oil from the oil tank 40. The directional control valve 43 in turn switches oil to flow to the B port. The oil flowing into the B port enters the second hydraulic chamber 17 of the hydraulic cylinder 1 via the second hose 24 and the second oil inlet / outlet 4.

The oil that has entered the second hydraulic chamber 17 is
As shown in FIG. 5, the check valve 25 is opened through the third flow path 35 of the piston and the valve pressing body 34. Therefore, the lock oil 18 flows backward from the lock hydraulic chamber 19 to the first hydraulic chamber 22, and as a result, the lifting bodies 11 and 16 descend while being guided by the guide rod 13 and the upper wall portion 7 of the outer cylinder housing 2.

[0034]

As is clear from the above description, the present invention has the following effects. (1) It is not necessary to mount or dispose a safety device on the outside of the hydraulic cylinder, and therefore a sufficient external space of the hydraulic cylinder can be secured. (2) The lifting / lowering body of the hydraulic cylinder can be immediately stopped at an arbitrary position simply by stopping the drive motor. (3) When the lifting / lowering body of the hydraulic cylinder is stopped at an arbitrary position, it is assumed that the first hydraulic chamber is leaked due to a leak from the cylinder packing or the hydraulic hose on the first oil inlet / outlet (drive) side is damaged. Even if the hydraulic pressure decreases, the piston as the lifting body and the inner cylinder housing do not descend. (4) It can be used in a field in which a hydraulic cylinder is used industrially, for example, in a vehicle maintenance lift in which the hydraulic cylinder is arranged in a vertical direction.

[Brief description of drawings]

 1 to 6 are explanatory views showing an embodiment of the present invention.

FIG. 1 is a schematic cross-sectional explanatory view of the present invention.

FIG. 2 is an enlarged explanatory view of a main part in FIG.

FIG. 3 is an explanatory view showing a main part in a perspective view.

FIG. 4 is an explanatory view of an operating state (elevation of an elevating body).

FIG. 5 is an explanatory diagram of an operating state (lowering of an elevating body). Especially, it is the operating state of the main part.

FIG. 6 is an explanatory diagram for explaining the operation of the present invention with reference to a hydraulic circuit diagram.

FIG. 7 is a schematic explanatory view showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydraulic cylinder, 2 ... Outer cylinder housing, 11 ... Piston, 13 ... Guide rod, 16 ... Inner cylinder housing, 17 ...
2nd hydraulic chamber, 18 ... Lock oil, 19 ... Lock hydraulic chamber, 2
2 ... 1st hydraulic chamber, 25 ... Check valve, 26 ... 1st flow path,
27 ... 1st flow path, 29 ... 2nd flow path, 30 ... 1st flow path, 34 ... Valve pressing body, 36 ... 3rd flow path, 37 ... Outer packing.

Claims (3)

[Claims] 1. A guide rod 13 slidably fitted in an outer cylinder housing 2 of a hydraulic cylinder 1 and slidably fitted to a guide rod 13 fixedly erected on an inner wall of a lower wall portion 5. The piston 11 and the outer cylinder housing 2 are slidably inserted through the opening 8 of the upper wall portion 7 of the hydraulic cylinder 1, and the lower end portion 16a is fixedly provided on the upper surface 11a of the piston 11. A cylinder housing 16 and a first hydraulic chamber 22 provided on the piston 11 and on the lower surface 11b side of the piston,
A lock hydraulic chamber 19 formed relatively between the inner wall of the inner cylinder housing 16 and the outer wall of the guide rod 13, and a second hydraulic chamber 17 formed between the outer cylinder housing 2 and the inner cylinder housing 16, respectively. Communication holes 27, 30, 3 for communicating oil
A lock structure for a lifting body of a hydraulic cylinder, which is composed of a check valve 25 having 6 and 6. 2. The check valve 25 according to claim 1,
When the piston 11 rises, the oil pressure-fed to the first hydraulic chamber 22 is supplied to the first passage 26 and the second passage 26 formed in the piston 11.
From the first hydraulic chamber 22 to the lock hydraulic chamber 19 via the flow path 29.
However, when the piston 11 stops at an arbitrary position, it does not flow in the opposite direction. On the other hand, when the piston 11 descends, the oil that is pumped to the second hydraulic chamber 17 is the third oil formed in the piston 11. A pilot check valve that opens the valve 32 through the flow path 35 and causes the lock oil 18 filling the lock hydraulic chamber 19 to flow into the first hydraulic chamber 22 as the guide rod 13 enters the inner cylinder housing 16. A lock structure for a lifting body of a hydraulic cylinder, which is characterized in that 3. A lock structure for an elevation body of a hydraulic cylinder according to claim 1, wherein the hydraulic cylinder 1 is arranged in a vertical direction.