JP3136449B2 - Load detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a load on a load by generating a fluid pressure proportional to the load.
And a device having a function suitable for load movement in addition to a load detection function.

[0002]

2. Description of the Related Art A load transmitting body which receives a load and a control valve which opens and closes in accordance with the load are provided. The working fluid is supplied to a hydraulic cylinder for generating an output through the control valve so that the load becomes weightless. As a working fluid control device for automatically generating a fluid pressure corresponding to a load, there is known a load detecting device suitable for luggage moving equipment as disclosed in Japanese Patent Application Laid-Open No. 62-201797. Have been.

The working fluid control device disclosed in Japanese Patent Application Laid-Open No. 62-201797 is connected to a first chamber into which a working fluid from a pressure generating source is introduced and a fluid passage through the first chamber and connected to a fluid pressure cylinder. A box having a variable volume second chamber, and a load transmitting body movably engaged with the box having a fluid discharge passage communicating with the second chamber and receiving a load of a load and moving in a load direction. A control valve built in the box for selectively opening and closing the fluid passage and the fluid discharge passage, and an elastic member for applying a force corresponding to a total weight of the box and a load transmitting member to a piston of the hydraulic cylinder. Configuration.

When the load is suspended and moved, the box is movably attached in a load direction to a case suspended from the piston via a wire, and the case is used as a part of a load transmitting body. When the luggage is suspended, the box floats in the case, and the thrust in the counter-load direction applied by the working fluid introduced into the fluid pressure cylinder to the piston and the working fluid sealed in the second chamber are applied to the case. The control valve shuts off the fluid passage and the fluid discharge passage in a state where the thrust in the counter-load direction applied to the box is equal to the thrust in the load direction applied to the box.

Here, when moving the load in the vertical direction, the case is moved up and down by holding the case by hand. For example, when the case is moved upward when the load is raised, the working fluid pressure in the fluid pressure cylinder and the second chamber is increased. And the box moves upward together with the case in an attempt to maintain an output relationship proportional to the thrust applied to the piston. That is, there is an advantage that the load can be raised or lowered only by moving the case up and down with a small force.

However, a box is built in a floating state so as to introduce a working fluid to a hydraulic cylinder and to provide a thrust balanced with a load to a case which is a part of a load transmitting body. Since the valve seat of the fluid discharge passage, which is a part, is built in, the configuration is extremely complicated. Further, the control valve is configured such that the fluid passage and the fluid discharge passage face each other and are opened and closed at both ends of the valve body, and since the valve body extends longitudinally through the second chamber, it is possible to prevent the whole from becoming longer and larger. Inevitable.

On the other hand, when the luggage is, for example, a part of an assembly and is moved to a predetermined position and the assembling operation is performed as it is, it is more workable to move the luggage directly than to move the case by hand. Is much more advantageous in terms of

However, when the user directly moves the suspended luggage, for example, downwardly, the load detector always detects the load of the luggage, so the load increases when a downward force is applied by hand. Just as in the case, the control valve opens and introduces the working fluid into the second chamber and the fluid pressure cylinder, generates a thrust opposing the downward force by hand, and tries to raise the load. It becomes impossible to move. In the case of moving the baggage upward, on the other hand, it is attempted to lower the luggage, so that it is impossible to move the baggage upward by hand.

[0009]

SUMMARY OF THE INVENTION There are two problems to be solved by the present invention, one of which is to generate a fluid pressure proportional to the load and supply the fluid pressure to a fluid pressure cylinder for supporting the load to load the load in zero gravity. The conventional load detecting device capable of supporting in a state is extremely complicated in structure,
It is large and not always convenient to handle. The other is that the conventional load detection device is inconvenient in operation because it has a configuration in which it is impossible to directly hold a load and move it vertically.

[0010]

According to the present invention, as a means for solving the first problem, a load receiving shaft for receiving a load of a load, a piston moving integrally with the load receiving shaft, and a piston are provided. A cylinder chamber fitted and partitioned into a fluid chamber and a back chamber, an inlet passage and an outlet passage communicating with the fluid chamber, a discharge passage communicating the back chamber with the outside, and a fluid chamber communicating with the back chamber. A discharge passage, an inlet valve provided in the inlet passage and opened when the piston moves in the direction of decreasing the volume of the fluid chamber, and a discharge valve provided in the discharge passage and opened when the piston moves in the direction of increasing the volume. With this configuration, the object of providing a compact and easy-to-handle load detecting device having a simple structure is achieved.

Further, as means for solving the second problem, in addition to the above-mentioned structure, a manual opening / closing valve is provided in the outlet passage so that the baggage can be moved vertically by directly holding the baggage by hand. The object of providing a load detection device which is convenient in operation is achieved.

[0012]

When a load acts on the load receiving shaft, the piston moves in the direction of decreasing the volume of the fluid chamber, and when the inlet valve is opened, the working fluid is introduced into the fluid chamber from the inlet passage, and the pressure increases the volume of the fluid chamber. Move in the direction and close the inlet valve. If the pressure of the working fluid acting on the piston is greater than the load, the piston moves further, opens the discharge valve, discharges the working fluid in the fluid chamber from the back chamber to the outside, and applies a force in the opposite load direction proportional to the load in the fluid chamber. In a balanced state.

In the case where an opening / closing valve is provided in the outlet passage, the valve can be closed when the above-mentioned balanced state is established, so that the fluid pressure cylinder for hanging the load can be prevented from responding to the change in load. You can move your luggage up and down by directly holding your luggage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described. In FIG. 1, a case 1 is composed of a middle body 2 and an upper lid 3 and a lower lid 5 which are superimposed on top and bottom and connected by bolts 4 and 6. The upper lid 3 has a suspension shaft 7, the lower lid 5 has a guide hole 8 penetrating vertically, and the upper surface of the middle body 2 is covered with the upper lid 3. Cylinder chamber 10 and insertion hole 9, inlet passage 13, and outlet passage 1
And 4.

The guide hole 8, the insertion hole 9, and the cylinder chamber 10 are arranged on the center axis of the case 1. A load receiving shaft 15 is inserted into these from below, and a piston 17 is inserted into the cylinder chamber 10. The load receiving shaft 15 is fitted in an O-ring 18 in a liquid-tight or air-tight manner.
6 is screwed into piston 17 and also piston 1
7 moves integrally with the piston 17 by a locking bolt 39 screwed into the bolt 7.

The cylinder chamber 10 is divided into a lower fluid chamber 11 and an upper back chamber 12 by a piston 17. An inlet passage 13 and an outlet passage 14 communicate with the fluid chamber 11, and the back chamber 13 has an upper chamber 13. A discharge passage 19 provided in the lid 3 constantly communicates with the outside of the case 1, that is, the atmosphere. Further, a discharge passage 20 that penetrates through the piston 17 and communicates the fluid chamber 11 and the back chamber 12 is provided.

The inlet passage 13 and the discharge passage 20 have an inlet valve 21 and a discharge valve 26 which open and close according to the position of the piston 17, respectively. That is, the inlet valve 21 and the discharge valve 26 are connected to the valve seats 2 formed in the respective passages 13 and 20.
2, 27, valve bodies 23 and 28 made of balls, and valve body 2
Valve closing springs 24, 2 for pressing the valve seats 3, 28 against the valve seats 22, 27, respectively.
9 and valve stems 25, 30 for separating the valve bodies 23, 28 from the valve seats 22, 27, and the valve stem 25 of the inlet valve 21 projects into the fluid chamber 11 through the inlet passage 13. Also,
The valve stem 30 of the discharge valve 26 passes through the discharge passage 20 and the back chamber 12
It protrudes.

Further, the outlet passage 14 has a manual on-off valve 31. That is, the on-off valve 31 includes a valve seat 32 formed in the passage 14, a valve body 33 made of a ball, a valve-closing spring 34 for pressing the valve body 33 against the valve seat 32, and a valve body 33 connected to the valve seat 3.
2 and a control lever 36. The valve stem 35 projects into a space 38 provided between the middle body 2 and the lower lid 5 and is rotatably supported by a pin 37. It is in contact with the operation lever 36.

In this embodiment having such a structure, the inlet passage 1
3 is connected to a pressure generating source of the working fluid, that is, an air pump and an accumulator when the working fluid is a gas, and a positive displacement liquid pump when the working fluid is a liquid, and the outlet passage 14 is connected to a predetermined cylinder such as a hydraulic cylinder for hanging a load. When the load is not acting on the load receiving shaft 15, the piston 17 is stopped at a position away from the valve stem 25 of the inlet valve 21.

When the load is suspended, a downward load is applied to the load receiving shaft 15, and the piston 17 moves downward, that is, in the direction in which the volume of the fluid chamber 11 decreases. For this reason, the valve stem 25 is
Is pushed away from the valve seat 22, and the opening of the inlet valve 21 introduces a working fluid from the inlet passage 13 into the fluid chamber 11 to generate a force for pushing up the piston 17. When this force overcomes the load of the load, the piston 17 moves upward,
1 and the inlet valve 21 is closed. When the inlet valve 21 is closed and the upward force of the working fluid introduced into the fluid chamber 11 is greater than the downward force of the load, the piston 17 moves further upward and the fluid chamber 1
1 to reduce the pressure of the working fluid and stop the piston 17 at a position where these forces are balanced.

When the upward force is larger by necessity, the piston 17 moves further upward and the valve stem 30 is moved upward.
Push the impact valve body 28 against the lower surface of the valve to separate it from the valve seat 27,
When the discharge valve 26 is opened, the working fluid in the fluid chamber 11 is discharged from the discharge passage 20 to the outside through the back chamber 12 and the discharge passage 19. For this reason, the pressure of the working fluid in the fluid chamber 11 decreases, and the piston 17 moves downward, and the discharge valve 26 closes to stop the piston 17 at a position where the force is balanced. When the working fluid is discharged more than necessary by the discharge valve 26, the piston 17 moves excessively downward to open the inlet valve 21, and the operation of moving upward again is repeatedly stopped.

That is, the piston 17 stops at a position where the force in the fluid load direction of the fluid chamber 11 in the counter load direction and the force in the load direction of the suspended load are balanced.
The discharge valves 26 are both closed. When the load increases in this state, the piston 17 moves downward to open the inlet valve 21 and introduce the working fluid to increase the pressure in the fluid chamber 11. When the load decreases, the piston 17 moves upward to open the discharge valve 26 and discharge the working fluid, thereby lowering the pressure in the fluid chamber 11.

As described above, a fluid pressure proportional to the load acting on the load receiving shaft 15 is generated in the fluid chamber 11, and the load is balanced with the upward force of the piston 17, which is the thrust in the anti-load direction. It is.

The configuration according to the first aspect of the present invention does not include the on-off valve 31 shown in FIG. FIGS. 2 and 3 show an example in which such a load detecting device is used for a luggage moving facility and a load measuring facility, respectively. However, when a load detecting device having the on-off valve 31 is used, the operating lever 36 may be fixed at the valve opening position.

In the equipment shown in FIG. 2, a pressure source 51 is connected to an inlet passage 13 by a supply pipe 52, and a lower working chamber 55 partitioned by an operating piston 54 of a fluid pressure cylinder 53 for hanging a load is provided at an outlet. The pipe 14 is connected to the passage 14 by a conduit 56, and the downwardly moving piston rod 57 of the operating piston 54 and the suspension shaft 7 are connected by a wire rope 58 so that the case 1 and the load 59 suspended on the load receiving shaft 15 can be connected to the fluid pressure cylinder 51. It was lifted by.

A working fluid having the same pressure as the fluid chamber 11 of the case 1 is always introduced into the working chamber 55 and generates a force for pushing up the operating piston 54.
7 and the operating piston 54 of the hydraulic cylinder 53
The load and the hydraulic cylinder 53
And the tensile force of the balance.

In this example of use, it is necessary to hold the case 1 by hand when moving the load 59 in the vertical direction, and when it is moved upward, the pressure in the fluid chamber 11 and the working chamber 55 decreases. The inlet valve 21 is opened and working fluid is introduced into these from the pressure source 51, so that the piston 17 and the operating piston 54 move upward by an equal stroke, and the piston 17 and the case 1 are integrally formed. Will rise. When the piston 17 and the case 1 are moved downward, the pressure in the fluid chamber 11 and the working chamber 55 increases, so that the discharge valve 26 is opened and the working fluid is discharged from these.

In the equipment shown in FIG. 3, a pressure source 61 is connected to an inlet passage 13 by a supply pipe 62, and a pressure gauge 63 is connected to an outlet passage 14 by a conduit 64.
5 and the case 1 is suspended by a wire rope
5, a load 67 is suspended.

As described above, a load acting on the load receiving shaft 15, that is, a fluid pressure proportional to the weight of the load 67 is generated in the fluid chamber 11, so that the pressure gauge 6 indicating the fluid pressure is generated.
3 allows the load to be read.

When the load is supported from below instead of being suspended, the load receiving shaft 15 is extended above the piston 17 so as to protrude from the upper lid 3, and the load is placed on the upper end thereof.

Next, the structure according to claim 2 of the present invention,
That is, FIG. 4 shows an example in which the load detecting device having the on-off valve 31 as in the embodiment of FIG.

That is, in this equipment, the pressure generating source 71 is connected to the inlet passage 13 by the supply pipe 72, and the supply pipe is connected to the lower working chamber 75 partitioned by the operating piston 74 of the hydraulic cylinder 73 for hanging the load. A conduit 80 branched from 72 is connected, a pilot setting chamber 81 of a pressure regulating valve 82 provided in the conduit 80 is connected to the outlet passage 14 by a pilot setting pipe 81, and a downwardly moving piston rod 76 of an operating piston 74 is connected to a suspension shaft. 7 are connected by a wire rope 77, and a case 1 and a load 79 which is detachably suspended from the load receiving shaft 15 by a wire rope 78 are lifted by a fluid pressure cylinder 73.

The pressure regulating valve 82 has a main valve body 85 which is seated on a main valve seat 83 formed in a conduit 80 by the force of a valve spring 84, and a driving piston 87 which pushes the main valve body 85 in an opening direction via a driving rod 86. And a relief valve 91 having an end portion of the drive rod 86 as a valve body 89 and a discharge passage 90 formed in the drive piston 87.
And the working fluid on the inlet side of the main valve body 85
And a pilot room 88, which is the back room.

In this use example, when the load is not suspended, the working fluid pressure generated in the fluid chamber 11 is not introduced into the pilot chamber 88 of the pressure regulating valve 82, so that the main valve body 85 is connected to the main valve seat 83. Is sitting.

When the load 79 is suspended, the operation lever 36
Is rotated in the counterclockwise direction in FIG.
The on-off valve 31 is opened by separating the valve 3 from the valve seat 32. The fluid chamber 11 contains the luggage 7 as described above.
A fluid pressure proportional to the load 9 is generated, which enters the pilot chamber 88 via the pilot setting pipe 81 and acts on the drive piston 87. The drive piston 87 is located in the pilot chamber 8
The main valve body 85 is opened in accordance with the difference between the fluid pressure of No. 8 and the working fluid pressure on the outlet side of the main valve body 85 and the spring force of the valve spring 84 to adjust the working fluid pressure from the pressure source 71. It controls the fluid pressure introduced into the working chamber 75 of the fluid pressure cylinder 73. When the fluid pressure in the working chamber 75 becomes equal to the fluid pressure in the fluid chamber 11, the main valve body 85 is closed. ing.

When the operating piston 74 stops at a position where the load of the load 79 is balanced, the operating lever 36 is released and the valve closing spring 34 presses the valve body 33 against the valve seat 32 to close the on-off valve 31. Then, the fluid pressure acting on the drive piston 87 is cut off from the load detecting device, and a pilot operation of a constant pressure proportional to the load is applied to the pressure adjusting valve 82.

In this state, if the load 79 is moved directly upward by directly holding it with the hand, the load is reduced.
The fluid pressure in the third working chamber 75 decreases, so that the main valve body 85 of the pressure regulating valve 82 opens to supply working fluid to the working chamber 75 until the pressure becomes equal to the fluid pressure in the fluid chamber 11.

On the other hand, when the load 79 is directly held by the hand and moved downward, the load increases and the fluid pressure in the working chamber 75 increases.
7 is pushed up, the relief valve 91 is opened, and the working fluid is discharged from the discharge passage 90 to the outside, so that the pressure becomes equal to the fluid pressure of the fluid chamber 11.

As described above, even if the load fluctuates because the load 79 is directly held by hand, the working chamber 75 of the fluid pressure cylinder 73 can be operated.
The use of a pressure regulating valve 82, such as the one described above, having the function of supplying or discharging the working fluid so that the fluid pressure of the load 79 is maintained at a constant pressure proportional to the load of the load 79 itself, The pilot pressure proportional to its own load is held by the on-off valve 31, and the load 79 can be arbitrarily moved in the vertical direction with a small force.

When the load is moved in the vertical direction as described above, the load detecting device always generates a fluid pressure proportional to the load so as to balance the load, so that the load detector moves vertically with the load. .

[0041]

As described above, according to the present invention, the working fluid is introduced into the fluid chamber having a variable volume by the piston moving in the cylinder chamber under the load of the load, and is sent to the inlet passage for introducing the working fluid from the pressure generating source to the predetermined equipment. An outlet passage and a discharge passage for discharge to the outside are provided, and the imbalance between the fluid pressure of the fluid chamber and the load is eliminated by opening and closing the inlet valve of the inlet passage and the discharge valve of the discharge passage. Is generated in the fluid chamber to be in a balanced state, so that the structure is extremely simple and sufficiently small, so that it is lightweight and easy to handle.

When a manual opening / closing valve is provided in the outlet passage, it is possible to hold the load directly by hand and move it vertically, which is extremely convenient for work.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a schematic view of a use example of the device of the present invention.

FIG. 3 is a schematic view of another use example of the device of the present invention.

FIG. 4 is a schematic view of still another use example of the device of the present invention.

[Explanation of symbols]

1 case, 10 cylinder chamber, 11 fluid chamber, 12
Back chamber, 13 inlet passage, 14 outlet passage, 15 load bearing shaft, 17 piston, 19 discharge passage, 20 discharge passage,
21 inlet valve, 26 release valve, 31 on-off valve,

Claims (2)

(57) [Claims] 1. A load receiving shaft for receiving a load of a load, a piston that moves integrally with the load receiving shaft, a cylinder chamber into which the piston is fitted and partitioned into a fluid chamber and a back chamber, An inlet passage and an outlet passage communicating with the chamber, a discharge passage communicating the back chamber with the outside, a discharge passage communicating the fluid chamber with the back chamber, and a piston provided in the inlet passage and the piston being provided in the fluid chamber. A load detecting device comprising: an inlet valve that opens when the piston moves in a direction in which the volume of the fluid chamber decreases; and a discharge valve that is provided in the discharge passage and opens when the piston moves in a direction in which the volume of the fluid chamber increases. . 2. A load detecting device according to claim 1, further comprising a manual on-off valve in said outlet passage.