JPH02161329A - Leak calibrator - Google Patents

Abstract

PURPOSE:To easily set a minute capacity change to a rod without reducing a cross-sectional area by generating a capacity change by a first and a second rods having different cross-sectional areas, which move in an empty chamber. CONSTITUTION:When a clearance L between a stopper screw 115 and a flange 113 of a second rod 107 is measured by a clearance gauge through a notch opposed by 180 deg. of a housing 103 and the screw 115 is turned, a capacity change is set by the clearance L. Therefore, when an operating piece 108 is turned, a flange 109 is pressed through a screw 112 and a first rod 106 whose diameter is smaller by a minute quantum than that of the rod 107, and the rod 107 move in accordance with the set quantum L. In such a way, a minute capacity change corresponding to a diameter difference of the rods 106, 107 and a moving stroke is generated in an empty chamber 104, and based on the corresponding minute differential pressure, a leak calibration is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a leak calibrator used in a leak testing device.

``Prior Art'' As shown in Fig. 3, the leak testing device applies equal air pressure to the object to be inspected (hereinafter referred to as the work) 1 and the reference tank 2 from the air pressure source 3, and shuts off the solenoid valves 4A and 4B. , the air pressure is sealed in the workpiece 1 and the reference tank 2, and after a predetermined period of time has elapsed in this state, the pressure difference between the two is detected by the differential pressure detector 5,
The detection signal is input to the quality determination device 6, and when the pressure difference reaches a predetermined value or more in the quality determination device 6, the workpiece 1 is
If there is a leak, the product is determined to be defective, and if no differential pressure occurs, the product is determined to be non-defective.

In the figure, 7 is a pressure reducing valve, 8 is a pressure gauge, and 9 is a three-way solenoid valve.
I am giving instructions. Furthermore, the three-way solenoid valve 9 is provided to release the air pressure contained in the workpiece 1 and the reference tank 2 to the atmosphere at the end of the inspection, and to return the pressure in the workpiece 1 and the reference tank 2 to atmospheric pressure.

The quality of the workpiece 1 is determined based on the voltage value detected by the differential pressure detector 5, but the relationship between the differential pressure and the amount of leakage cannot be determined uniquely.

In other words, the allowable leakage depends on the internal volume of workpiece 1! (leakage amount per unit time) will be different values. For this reason, it is necessary to perform calibration for each internal volume of the workpiece 1 to determine its acceptability.

Calibration is performed using a leakage calibrator 11 provided on the workpiece 1 side. The leakage calibrator 11 has a structure that allows the internal volume to be changed by a predetermined amount, and by applying this change in internal volume to the workpiece L side with the leak-free workpiece 1 connected, for example, the workpiece L is measured isometrically. A predetermined amount of leakage can be given to the amount of leakage, and the differential pressure value corresponding to the amount of leakage is defined and set as a standard for determining quality.

A conventionally used leak calibrator 11 has cavities 13, 14 and 15 in a housing 12, as shown in FIG. 4, and a piston 16 is provided between the cavities 13 and 14.

The piston has a rod 17, which is inserted into a hole formed in the end plate of the housing 12, and the piston 16
is supported so as to be movable along the axis of the cavity 14.

A spring 18 is applied to the piston 16, and the repulsive force of the spring 18 causes the piston 16 to be elastically pressed against the stopper 19.

At the end of the housing 12 is an adjustment shaft 2 for a micrometer.
1 is attached, and by rotating the knob 22, the adjustment shaft 21 is moved laterally.

The position of the stopper 19 is set so that the tip of the adjustment shaft 21 is in contact with the end of the rod 17 and the micrometer knob 22 points to zero on the scale.

With this setting in place, the adjustment shaft 21 is moved to the right by a predetermined amount, for example, to set the volume change amount.

The empty chamber 15 is connected to the piping on the work l side through the connection port 23. Air pressure is applied to the empty chamber 13 through a connection port 24 to one input port of a three-way 'R11l valve, which is connected to a three-way solenoid valve (not particularly shown), and the air pressure is applied to the empty chamber through the three-way solenoid valve. 13, and this air pressure causes the piston 16 to move to the right as shown by the dotted line against the repulsive force of the spring 18.

The movement of the piston 16 causes the end of the rod 17 to fill the empty chamber 1.
5, the volume of the cavity 15 is changed by the stroke L, the end of the rod 17 is brought into contact with the adjustment shaft 21, and this state is maintained.

Incidentally, an air pressure equal to the air pressure applied to the work l is applied to the connection port 23A to maintain equal pressure between the chambers 15 and 14 to prevent air from leaking between them.

To perform calibration, it is sufficient to release the air pressure applied to the connection port 24.By removing the air pressure applied to the connection port 24, the piston 16 moves to the left by a stroke L due to the counter force of the spring 18, and at this time. The volume of the cavity 15 increases by an amount corresponding to the stroke L, and a pressure drop equivalent to leakage is given to the workpiece 1 connected to the connection port 23.

Due to this pressure drop, a differential pressure is generated in the differential pressure detector 5,
Calibration is performed by specifying the value of differential pressure with respect to volume change.

"Problem to be Solved by the Invention" With such a structure, the volume of the empty chamber 15 changes depending on the amount of movement of the rod 17.

Therefore, in order to generate a volume change corresponding to a minute leak, the movement stroke L of the rod 17 must be made small (or the diameter of the rod 17 must be made extremely thin).

In order to set the displacement stroke L of the rod 17 small and to set the amount of volume change with high precision, the scale adjustment shaft 21 of the micrometer knob 22 must be moved with high precision, so there is a limit to this. be.

Furthermore, if the diameter of the rod 17 is made thinner, it becomes difficult to seal between the housing 12 and the rod 17. In other words, the O-ring 25 must be used for small diameters, but there are no O-rings for small diameters. For this reason, there is a limit to how thin the diameter of the rod 17 can be made.

Furthermore, air pressure is used as a means for moving the rod 17, but this requires a controller such as a three-way solenoid valve, which is expensive. The micro makeup knob 22 does not have a stopper function for the set value. Therefore, in order to move the adjustment shaft 21 to the position where a predetermined volume change is to be given, it is necessary to specify the scale using the micrometer knob 22, which makes the operation for setting the predetermined volume change cumbersome. There are drawbacks.

The purpose of this invention is to provide a leakage calibrator that can give a minute volume change without reducing the cross-sectional area of the rod, and that can be easily operated to set a predetermined volume change. That is.

"Means for Solving the Problems" In the present invention, a cavity constituting a variable capacity tank is provided in the housing, one end of a first rod is provided in the cavity so as to be movable forward and backward, and a second rod is provided at the tip of the first rod. A second rod slightly thicker than the diameter of the rond is connected, and this connecting part moves within the cavity, and the first rod and the second rod move according to the amount of movement.
The structure is such that a change in volume occurs due to a change in volume due to a difference in cross-sectional area of the rods.

According to the leakage calibrator of this invention, the change in volume within the chamber is caused by the first
Because it is given by the difference in volume caused by the difference in cross-sectional area between the rod and the second rod, it is possible to obtain a minute change in volume without making the diameter of the rod thinner or without making the stroke of the rod move minutely. .

Therefore, according to the present invention, it is possible to provide a leak calibrator that is easy to manufacture and has high accuracy.

"Embodiment" FIG. 1 shows an embodiment of the present invention. In the figure, 100 indicates a housing. In this example, this housing 100 connects an operation housing 102 and a stopper housing 103 to both ends of a main housing 101.
The case where 00 is configured is shown.

That is, the operation housing 102 and the stopper housing 10
3 is screwed and connected to male screws formed on the outer periphery of both ends of the main housing 101.

The main housing 101 has a hollow space 10 formed by a through hole in its axis.
4 is formed. This empty space 104 is the operation housing 10
A first hole 104A with a small diameter formed from the 2 side and a second hole 104 with a large diameter formed from the stopper housing 103 side.
It is composed of B.

The first hole 104A having a small diameter is formed relatively shallowly, and most of the first hole 104A is occupied by the second hole 104B. A hole 105 is communicated with the second hole 104B from the outer peripheral surface of the main housing 101, and the second hole 104B is connected to, for example, the workpiece side through this hole 105.

A first rod 106 protruding from the operation housing 102 is inserted into the first hole 104A. First rod 106
is movable forward and backward within the first hole 104A by an operator 108 provided in the operation housing 102.

That is, a flange 109 is provided at the end of the first rod 106, and a spring 111 is applied to the flange 109, so that the first
A biasing force is applied to the rod 106 toward the stopper housing 103 side. At the same time, a screw 112 is connected to the end of the first rod 106, and this screw 112 is led out from the end of the operation housing 102, and the operator 108 is screwed into this lead-out portion, and the operator 108 is rotated. By operating the first rod 106, the first rod 106 is driven to move forward and backward.

In this example, a wing nut is used as the operator 108, but in another example, a knob-type latch 1- or the like that can be rotated with a finger can be used. Operator 10
By rotating the spring 8, the first rod 106 is
It can be moved forward or backward by the biasing force 11.

A second rod 107 is connected to the tip of the first rod 106 . This second rod 107 has a diameter slightly smaller than the inner diameter of the second hole 104B, and is housed within the second hole 104B.

The length of the second rod 107 is selected to be approximately equal to or slightly smaller than the length of the second hole 104B.

A flange 113 is attached to the distal end side of the second rod 107, and this flange 113 abuts against the end of the main housing 101, thereby defining the end of rightward movement of the second rod 107.

O-rings 114A and 114B are attached to each end of the first hole 104A and the second hole 104B.
, 114B, the first hole 104A and the second hole 104B are shielded from the outside air, and the distance between the outer circumferential surfaces of the first rod 106 and the second rod 107 and the inner circumferences of the first hole 104A and the second hole 104B is A vacant room 104 is formed. Note that 116 and 117 are retainers that restrain the O-rings 114A and 114B.

The volume of the cavity 104 is formed by the gaps between the first hole 104A, the second hole 104B, the first rod 106, and the second rod 107, and can therefore be set to a minute value. Further, if the length of the second rod 107 is made smaller than the length of the second hole 104B, the void portion of the second hole 104B increases accordingly, so that the initial volume can be set to an appropriate value.

The stopper housing 103 has a stopper screw 11 at the end.
5, and the gap between the end of the stopper screw 115 and the flange 113 allows the first iron 106 and the second
The movement stroke of the rod 107 is determined, and the empty space 104
The amount of change in volume is defined.

The stopper housing 103 is used to set the gap.
As shown in Figure 2, there are notches 10 at 180° opposing positions.
3A, 103B are formed, and these notches 103A, 103B are formed.
This allows the gap between the stopper screw 115 and the flange 113 to be measured. The gap (1) can be measured using a feeler gauge or other lubricating means.

In the standby state, the first rod 106 and the second rod 107 are drawn to the right, and the flange 113 is in contact with the restraining plate 117.

In order to give an isometric leakage amount to the workpiece side, it is sufficient to loosen the operator 10B and move the first rod 106 and the second rod 107 to the left.

When the first rod 106 and the second rod 107 are moved to the left, the amount of the second rod 107 in the empty space 104 gradually decreases, and the amount of the first rod 106 increases. As a result, the volume of the empty chamber 104 gradually increases according to the volume difference between the first rod 106 and the second rod 107 relative to the amount of movement, and when the flange 113 collides with the stopper screw 115, the volume of the empty chamber increases by a preset amount. That's what I did.

Therefore, by capturing and storing the differential pressure value generated at that time, the relationship between the differential pressure value and the specified leakage amount is calibrated, and a dark value for determining the quality of the workpiece can be set.

“Modified Embodiment” In the above description, a case has been described in which the operator 108 is manually operated using a hinged lever, but it is also possible to form two holes that communicate with the inside from the outer peripheral surface of the operation housing 102 and attach a flange 107 to the piston. The first rod 106 and the second rod 107 are connected by applying air pressure from one of the two holes.
It can also be configured to be moved by pneumatic pressure.

"Effects of the Invention" As explained above, according to the present invention, the connecting portions of the rods 106 and 107 having different diameters are arranged in the empty space 104, and the connecting parts of the rods 106 and 107 having different diameters are arranged in the empty space 104.
Since the structure is such that the volume of the cavity 104 is changed by changing the amount present in the rod, the amount of change in volume can be reduced without reducing the diameter of the rod.

Also, regarding the movable amount of the rod, the first rod 106 and the second rod
Since the volume of the empty chamber 104 changes in accordance with the difference in volume between the rods 107, the amount of change in volume with respect to the amount of movement of the first rod 106 and the second rod 107 can be reduced.

Therefore, a minute change in volume can be obtained without making the amount of movement of the first rod 106 and the second rod 107 extremely small.

As a result, the amount of change in volume with respect to the movement stroke L can be defined with high accuracy.

Furthermore, since the leak calibrator according to the present invention has a simple structure, it can be manufactured at low cost, and has the advantage that a highly accurate leak calibrator can be provided at low cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is a side view thereof, Fig. 3 is a prong diagram for explaining the outline of the leak test device, and Fig. 4 is a diagram showing a conventional leak calibrator. It is a sectional view for explanation. 101: Main housing, 102: Operation housing, lO
3: Stopper housing, 104: Vacant chamber, 106: First rod, 107: Second rod.

Claims (1)

[Claims] (1) One end of a first rod is provided in a cavity constituting a variable capacity tank so that it can move forward and backward, and a second rod that is slightly thicker in diameter than the first rod is connected to the tip of this first rod, and this connecting portion The leak calibrator moves within the cavity and generates a volume change due to a difference in cross-sectional area between the first rod and the second rod according to the amount of movement.