JPH0156688B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a hydraulic weighing device.

Conventionally, electronic weighing devices using load cells and the like have been widely used, but since the load cells in these known weighing devices are extremely expensive, the price of the weighing device is also high, and therefore demand is limited. It was becoming.

On the other hand, a hydraulic weighing scale using a Bourdon tube type instrument has been considered as an inexpensive weighing device, but in a hydraulic weighing scale, when an object to be weighed is placed on the weighing platform, It has been found that there is a fundamental drawback in that impulsive pressure waves are created in the hydraulic pipes, and as a result the stability of the pointer of the instrument is disturbed.

The object of the present invention is to eliminate the above-mentioned drawbacks and provide a weighing device that is significantly cheaper than the known load cell type weighing device.
An object of the present invention is to provide an improved hydraulic weighing device.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show a longitudinal sectional view and a plan view of the hydraulic weighing device of the present invention.

This weighing device has a weighing table 2 having a substantially rectangular shape. A pressure receiving section 1 is arranged at the lower four corners of the weighing table 2, and the weighing table 2 is supported on the pressure receiving section 1. As shown in FIG.
and a cylinder 12 standing upright on the substrate 11.
and a piston 13 housed in the cylinder 12 and protruding upward from the cylinder 12.
The weighing platform 2 is made up of the piston 13.
It is fastened to by a fixture 21 or the like.

A connector 3 connected to the cylinder 12 of each pressure receiving part 1 via a pressure receiving pipe 4 is disposed below the center of the weighing table 2, and the connector 3 is connected to a Bourdon tube type load meter that stands upright on the side of the weighing table 2. 7 via an instrument pipe 5. Further, an oil supply pipe 6 is connected to the connector 3, and a pot K is provided in the pipes 5 and 6.

Next, the detailed structure of each part will be explained with reference to FIG. 3 and subsequent figures.

Structure of the Pressure Receiving Part As shown in FIG.
The top of the piston 13 protrudes from the cylinder 12 and is fastened to the weighing platform 2 (see FIGS. 1 and 2) via a fixture 21.

A chamber 121 is formed at the bottom of the cylinder 12, and a connection port 111 provided on the substrate 11 communicates with the chamber 121. The connection port 111 is connected to the board 11
It opens at the outer peripheral edge of the pipe 4 and is connected to the pressure receiving pipe 4. Inside the chamber 121 is a piston 1.
Barrel-shaped tip large diameter part 131 provided at the lower end of 3
is accommodated and a bowl-shaped oil-resistant seal member 1
4 is accommodated. This oil-resistant seal member 14
is fixed by the base plate 11 and the cylinder 12 at its outer peripheral flange portion 141, and is in contact with the lower surface of the large diameter portion 131 at the tip end of the piston 13 at its central rising portion 142. The rising portion 142 can be elastically deformed according to the vertical movement of the piston 13, and a sealed working chamber 122 that communicates only with the connection port 111 is formed within the rising portion 142.

A cylindrical chamber is provided above the chamber 121 with an inner flange 123 in between, and a cylindrical ball slide 125 having a cylindrical ball race 124 is accommodated in the chamber. ball race 1
A large number of ball grooves extending in the cylindrical direction are provided on the inner peripheral surface of the ball 24, and a large number of steel balls 126 that can rotate only within the ball grooves are accommodated in the ball grooves. The inner diameter of the ball slide 125 is approximately equal to the outer diameter of the upper shaft portion 132 of the piston 13, and therefore the steel ball 126 is engaged with the outer peripheral surface of the shaft portion 132 of the piston 13. As a result, piston 13
When the steel ball 12 moves up and down in the cylinder 12, the steel ball 12
6 rotates in the ball groove, the frictional resistance when the piston 13 moves up and down becomes extremely small.
Further, since the large diameter end portion 131 of the piston 13 is formed to have a barrel-shaped outer circumferential surface, the contact between the large diameter end portion 131 and the inner circumferential surface of the cylinder 12 is a line contact, and therefore the frictional resistance is reduced. It is also extremely small compared to a normal piston-cylinder mechanism.

Furthermore, since the working chamber 122 is sealed against the piston 13, oil leakage is completely prevented.

Note that a material having a shape as shown in FIG. 4 may be used as the oil-resistant sealing material.

Structure of Connector The connector 3 has a substantially cylindrical main body 31 as shown in FIG.
11 is provided, and a second connecting hole 312 for connecting the instrument pipe 5 is provided on the top surface of the main body 31.
is provided. There is a connecting hole 31 inside the main body 31.
A buffer chamber 313 communicating with 1,312 is provided,
A buffer body 32 is provided in the chamber 313 so as to cross the buffer chamber 313 orthogonally to the axis of the connecting hole 312 . The buffer body 32 is plate-shaped, and the buffer chamber 3
13 to the connecting hole 312 and the connecting hole 311
It is divided into a side that communicates with the

As shown in FIG. 5, the buffer body 32 includes a first channel 321 facing toward the connecting hole 312, a second channel 322 orthogonal to the channel 321,
It is provided with a zigzag type flow path consisting of a third flow path 323 orthogonal to the flow path 322, and the connecting hole 31
1 and 312 can communicate with each other only through this zigzag flow path.

A connecting hole 314 for the oil supply pipe 6 is further provided on the outer peripheral surface of the main body 31, and this connecting hole 314 also communicates with the buffer chamber 313 inside the main body 31.

Explanation of Actions and Effects Before using the device of the present invention, open the tank K of the oil supply pipe 6 and the pipe K of the instrument pipe 5, and connect the oil supply pipe 6 to each pressure receiving part 1, load cell 7, and connector 3. Fill with oil.

When an object to be weighed is placed on the weighing platform 2, the piston 13 of each pressure receiving part 1 is suddenly loaded downward via the weighing platform 2, the piston 13 moves downward, and the oil-resistant seal member 14 is deformed downward. As the volume of the working chamber 122 decreases, the working chamber 12
A pressure wave is generated in the piston 2 due to the sudden load on the piston 13. This pressure wave is transmitted into the pressure receiving pipe 4 through the connection port 111 provided on the substrate 11, and further into the main body 31 of the connector 3. However, there is a buffer body 32 inside the main body 31 of the connector 3.
is provided, so that the main body 3 can be connected from the connecting hole 311.
Most of the pressure waves entering the inside of the connecting hole 312 are blocked by the buffer body 32, and only substantially static pressure is transmitted to the connecting hole 312. That is, the pressure waves that enter the main body 31 of the connector 3 through the connection hole 311 are not affected by the buffer body 32 because the buffer chamber 313 extends in a direction perpendicular to the direction in which the pressure waves travel. The reaching pressure wave is only the right angle component of the pressure wave entering from the connecting hole 311, and the pressure wave reaching the flow path 32 of the buffer body 32 is
Most of the pressure waves entering the channel 323 are reflected at the end of the channel 323, so that the pressure waves entering the channel 322 are only the orthogonal components of the pressure waves entering the channel 323. Similarly, since only the right angle component of the pressure wave is transmitted at the end of each flow path, the pressure wave entering the connecting hole 312 becomes extremely small, and therefore almost no dynamic pressure wave is introduced into the load cell 7. Not done. As a result, in the device of the present invention, the movement of the pointer in the load cell 7 is stable, allowing accurate weighing.

Further, according to the present invention, an inexpensive hydraulic weighing device that has conventionally been impossible to realize for pressure waves inside a pipe can be put to practical use, so that the applications of the weighing device can be expanded.

Note that the buffer body 32 is not limited to the shape shown in FIG. 5, and may be used as long as it has a zigzag curved flow path inside.

FIG. 6 shows another buffer body 8, and the buffer body 8 shown in the figure is constructed by stacking several plate members 81 to 84 on top of each other.

As shown in FIG. 7, the plate member 81 has a hole 811 penetrating through the center and a circular recess 812 formed on one surface of the plate member, and the hole 811 and the recess 8 communicate with each other. There is.

Further, as shown in FIG. 8, the plate member 82 has a recess 821 having the same diameter as the recess 812 on one surface thereof, and a hole 822 extending along the inner peripheral edge of the recess 821. (The plate member 84 is
Since it has the same structure as 2, the explanation will be omitted. ) On the other hand, the plate member 83 has only a hole 831 extending through the center, as shown in FIG.

The buffer member 8 is constructed by overlapping these plate members 81 to 84 as shown in FIG.
Since zigzag channels are formed therein that are perpendicular to each other, if this buffer member 8 is used in place of the buffer member 32, the same effect as that obtained by using the buffer member 32 can be obtained. It will be done.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional side view of the hydraulic weighing device of the present invention, Fig. 2 is a plan view of Fig. 1 with the weighing platform removed, and Fig. 3 is a longitudinal sectional view of the pressure receiving part that supports the weighing platform. , FIG. 4 is a vertical sectional view showing a modified example of a part of the part shown in FIG. 3, FIG. 5 is a vertical sectional view of the connector, and FIG. 6 is a modified example of the buffer body used with the connector. 7 is a view in the direction of the − arrow in FIG. 6, FIG. 8 is a view in the direction of the − arrow in FIG. 6, FIG. 9 is a view in the direction of the − arrow in FIG. 6,
It is. 1: Pressure receiving part, 2: Weighing stand, 3: Connector,
4: Pressure receiving piping, 7: Load cell, 8, 32: Buffer body.

Claims (1)

[Scope of Claims] 1. A weighing platform on which an object to be weighed is placed, a pressure receiving section that supports the weighing platform, a connector connected to the pressure receiving section via pressure receiving piping, and a weighing platform connected to the connector via instrument piping. a Bourdon tube type load cell connected to the weighing platform, the pressure receiving section includes a piston that supports the weighing platform, and a cylinder that accommodates the piston, and the piston is barrel-shaped. The cylinder has a large-diameter tip portion having an outer circumferential surface and a shaft portion with a uniform diameter that is connected to the large-diameter tip portion, and the cylinder accommodates the large-diameter tip portion and is connected to the pressure receiving piping. The chamber includes a chamber having a connection port, and a ball slide that engages with the outer peripheral surface of the shaft to smoothly slide the shaft in the axial direction. A bowl-shaped oil-resistant seal member that can be expanded and contracted by engaging with an end surface of the part is housed, and the oil-resistant seal member forms an operating chamber that communicates only with the connection port, and connects the working chamber with the piston. The connector has a first connecting hole for connecting the pressure receiving pipe, and a first connecting hole arranged at right angles to the first connecting hole and for connecting the instrument pipe. a second connecting hole;
a buffer chamber extending parallel to the second connecting hole and communicating with the first and second connecting holes; and a buffer chamber provided across the buffer chamber so as to be perpendicular to the axis of the second connecting hole. a buffer body dividing the buffer chamber into at least two spaces, the buffer body having a zigzag bent flow path therein, and connecting the first and second connections. A hydraulic weighing device, wherein the holes are configured to be able to communicate with each other only through the flow path of the buffer body.