JPS6146433Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is used in a leak detection device that detects leaks by applying the same air pressure to the reference tank and the workpiece, and then detecting the pressure difference between the reference tank and the workpiece. The present invention relates to a volume change adder used for sensitivity calibration and correspondence between leakage amount and detected differential pressure.

In the leak detection device, for example, as shown in FIG. 1, the air pressure of a pneumatic pressure source 11 is lowered to a test pressure through a pressure reducing valve 12, and the air at the test pressure is further divided into two parts through a three-way solenoid valve 13 and then divided into two parts. It is added into the workpiece 16 and reference tank 17 through valves 14 and 15, respectively. After making the pressure in the workpiece 16 and the reference tank 17 the same, the two-way solenoid valves 14 and 1
5, and then the workpiece 16 and the reference tank 1
7 is detected by a differential pressure detector 18. If there is no leakage in the workpiece 16, the pressure difference between the workpiece 16 and the reference tank 17 is zero. However, work 1
If there is a leak in tank 6, the pressure in workpiece 16 will decrease below the pressure in reference tank 17, and this will be detected by differential pressure detector 18.
Detected at

In such a leak detection device, it is a matter of course that the sensitivity must be constant. In order to check whether the sensitivity has changed, a volume change adder 19 is installed in the pipe to which the workpiece 16 is connected.
The volume of the volume change adder 19 is changed by a constant value, that is, a constant leakage is equivalently given to the workpiece 16, and the pressure difference detected by the differential pressure detector 18 at that time is a predetermined value for the same workpiece. If so, the sensitivity has not changed, but if the detected pressure difference is smaller than a predetermined value, it can be determined that the sensitivity of the differential pressure detector 18 has decreased.

Furthermore, if the internal volume including the work 16 and its piping is known, the work 16 and the reference tank 1
7 is set to atmospheric pressure, the internal volume on the workpiece 16 side is increased by a certain value using the volume change adder 19,
By measuring the detected value of the differential pressure detector 18 at that time, it is possible to know the relationship between the detected differential pressure and the amount of leakage.

In this way, in this type of leak detection device,
A volume change adder 19 was required. The conventional volume change adder has a cylinder 21 as shown in FIG.
A piston 22 is disposed within the cylinder so as to be movable along the axis, and the piston 22 airtightly divides the cylinder 21 into two. The piston 22 is connected to one end of a shaft 23 disposed at the axial center position, the shaft 23 projects outward from one end of the cylinder 21, and the projecting end is connected to a micrometer head 24.
When the micrometer head 24 is rotated, the shaft 23
moves along its extension direction and is thus divided by the piston 22 in the cylinder 24.
The volume of the space 25 on the opposite side to 3 changes. This space 25 is communicated with the outside formed at the other end of the cylinder 21 via a communication hole 26, for example, to a pipe leading to the workpiece 16 in FIG. In this way, the volume change adder 19 is connected as described above.

The conventional volume change adder rotates the micrometer head 24 in order to change the volume in this way, which is manually performed each time, which is cumbersome and cannot be done in a short time. Nakatsuta. In particular, as the amount of change in volume increases, the number of revolutions of the micrometer head 24 increases, and the time required to change the volume increases.
This length of time means that if there is a temperature change while the volume is being changed, correct sensitivity checks and leakage amount calibrations cannot be performed. Further, as mentioned above, since the volume is changed by the rotation of the micrometer head 24, it is difficult to automate it. In other words, it is difficult to automatically perform a sensitivity check in a short period of time.

The purpose of this invention is to provide a volume change adder that can give a volume change in a very short time, can give an arbitrary volume change accurately and within a limited range, and is easy to automate. It's about doing.

FIG. 3 shows an example of a volume change adder according to this invention, in which a piston 34 is arranged movably along the axis in a cylinder 33 whose both ends are closed with end plates 31 and 32. In this design, the piston 3
4, the cylinder 33 is located in the space 35 on the end plate 31 side.
, a space 36 on the end plate 32 side, and a space 37 between these spaces in an airtight manner. Also piston 3
4, stoppers 38 and 39 are inserted from the end plate 31 side and 32 side, respectively, so as to limit the movement range of the cylinder 33. One stopper 38 is fixed, but the other stopper 39 is attached to the axis of the cylinder 33. The position on the top can be adjusted.

That is, the rod-shaped stopper 38 is inserted into the cylinder 33 through the center hole of the end plate 31 and is fixed therein. Similarly, a rod-shaped stopper 39 projects into the cylinder 33 from the center hole of the end plate 32. The outside of the cylinder 33 of this stopper 39 is attached to a micrometer head 41. Therefore, when the micrometer head 41 is rotated, the rod-shaped stopper 39 moves along the axial direction of the cylinder 33. The inner diameter of the cylinder 33 on the side where the stopper 39 is located is made smaller, and a stepped portion 42 is formed between it and the other portions.

A ring-shaped groove is formed along the circumferential surface of the piston 34, and an O-ring 43 is fitted into the groove to airtightly separate the two sides of the piston 34. A piston shaft 44 is integrally attached to the center of the piston 34 on the end plate 32 side. The end of the piston shaft 44 on the end plate 32 side is fitted into the small diameter portion of the cylinder 33. A groove along the circumferential direction is formed on the circumferential surface of the inserted part, and the O-ring 4 is inserted into the groove.
5 is fitted, and the above-mentioned spaces 36 and 37 are separated by this O-ring 45.

The piston 34 is biased by a spring against one of the stops 38,39. For example, a coil spring 46 centered around the piston shaft 44 connects the piston 34 and the stepped portion 4.
2, and the piston 34 is pressed against the stopper 38 by the spring 46. piston 3
Wear-resistant fourth and third reinforcing pieces 4 on both ends of 4.
7 and 48 respectively, and stoppers 38 and 3.
Similarly, second and first reinforcing pieces 51, 5 are provided on the end face of 9.
2 are attached to each of the stoppers 38 and 39, so that even if the piston 34 collides with the stoppers 38 and 39, these are not easily damaged.

Space 35, 3 divided into three in cylinder 33
6, 37 and passages 53, 54, 55 communicating with the outside
are formed in the cylinder 33, respectively. space 36
is connected to a tank to be tested such as a workpiece by a passage 54, and passages 53 and 55 are configured to connect the spaces 35 and 37 to an external pneumatic source, respectively.

In order to apply a volume change to the workpiece side of the leak detection device using the volume change adder having the configuration described above, for example, as shown in Figure 4, in which parts corresponding to Figure 1 are given the same numbers, The pressure source 11 is connected to the space 35 through the three-way solenoid valve 56 and further through the passage 53, and the pressure source 11 is branched at the middle of the pressure reducing valve 12 and the three-way solenoid valve 13 and connected to the space 37 through the passage 55. is branched off and connected to the space 36 through a passage 54. By adjusting the micrometer head 41, the movable stopper 39 is set so that its end face is in the position shown, for example, by the dotted line in FIG. In the initial state, the three-way solenoid valve 56 applies the air pressure from the air pressure source 11 to the space 35.
Therefore, since the air pressure in the space 35 is greater than that in the space 37, the piston 34 is pushed toward the end plate 32 against the biasing force of the spring 46, and the end surface of the piston shaft 44 moves to the dotted line position. The piston 34 abuts the stop 39 and is separated from the fixed stop 38.

To change the volume from this state, the three-way solenoid valve 56 is controlled to communicate the space 35 with the atmosphere.
Therefore, the air pressure in the space 37 becomes greater than the air pressure in the space 35, and the piston 34 instantly moves toward the fixed stopper 38 due to the spring force of the spring 46 and collides with it. In this way, the volume of the space 36 is
Cylinder 3 determined by the moving distance L ₁ of the piston 34
The volume of the small diameter portion of No. 3 increases instantaneously. If this increased volume is set in advance by adjusting the micrometer head 41, an accurate volume change can be instantaneously provided. Therefore, there is no possibility that a temperature change will occur during the volume change, resulting in an erroneous measurement. Furthermore, since the volume is changed by controlling the electromagnetic valve, it is easy to automatically change the volume without manual intervention.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing a leak detection device, Fig. 2 is a sectional view showing a conventional volume change adder, Fig. 3 is a sectional view showing an example of a volume change adder according to this invention, and Fig. 4 is a sectional view showing this conventional volume change adder. It is a figure showing the state where the volume change adder of the invention is connected to a leak detection device. 31, 32: end plate, 33: cylinder, 34: piston, 35, 36, 37: divided space in cylinder 33, 38: fixed stopper, 39: movable stopper, 41: micrometer head, 44 piston shaft, 46: Spring, 53, 54, 55: Each passage between the spaces 35, 36, 37 and the outside.

Claims (1)

[Scope of utility model registration request] a cylinder, a movable stopper inserted from one end of the cylinder, a first reinforcing piece attached to an end face of the movable stopper in the insertion direction, means for adjusting the position of the movable stopper in the cylinder axial direction, and a movable stopper inserted from one end of the cylinder; A fixed stopper inserted from the other end, a second reinforcing piece attached to the end face of the fixed stopper in the insertion direction, and a second reinforcing piece that can be moved between the movable stopper and the fixed stopper within the cylinder, and a second reinforcing piece attached to the end face of the fixed stopper in the insertion direction. Third and fourth reinforcing pieces that can come into contact with the first and second reinforcing pieces, respectively, are attached, and the space on the movable stopper side, the space on the fixed stopper side, and the space between these are provided with the cylinder. a piston that airtightly divides the interior thereof; a coil spring that is attached along the outer peripheral surface of the piston and biases the piston toward either the movable stopper or the fixed stopper; and a space on the movable stopper side within the cylinder; A volume change adder for a leak detection device, comprising a passage that communicates between tanks to be tested, and a passage that is arranged so that the space on the fixed stopper side or the intermediate space can communicate with an external air pressure source.