JPH0873024A - Method of distinguishing direction of stud bolt and direction distinguishing device - Google Patents

Abstract

PURPOSE: To accurately distinguish the direction of a stud bolt by the difference of the length of the screw part on both sides of the stud bolt. CONSTITUTION: The air 8 of an air supply source 9 is sprayed to the shaft part 1a of a stud bolt 1 inserted into a distinguishing hole 5 of a direction distinguishing body 3 through a direction detector 7 from a first air hole 2a and a second air hole 2b in two places of a fixed position, and the piston 12 of the air cylinder 11 of the direction detector 7 is displaced by the air pressure difference of the respective holes 2a, 2b to detect the displacement direction by a sensor 14 for detecting the presence of a piston rod 13. The air pressure of either one of the first air hole 2a or the second air hole 2b becomes high according to whether the direction of the stud bolt 1 inside the distinguishing hole 5 is a regular direction or a reverse direction, and the magnitude of the air pressure is distinguished by the displacement direction of the piston rod 13, thereby distinguishing the direction of the stud bolt 1 inside the direction distinguishing body 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction discriminating method and a direction discriminating apparatus based on the lengths of threaded portions of stud bolts having different lengths of threaded portions at both ends.

[0002]

2. Description of the Related Art Most stud bolts having threaded portions at both ends have different shapes such as the length of the threaded portions at both ends and the thread pitch. When automatically supplying stud bolts with different threaded forms on both ends to automatic bolt assembly machines such as impact wrenches, the stud bolts that are aligned and conveyed from the parts feeder in the axial direction are screwed on both sides of the shaft. The direction is determined by the difference in the form of the parts, and the screw parts of the same form are aligned so that they face in a fixed direction, and are automatically supplied to an impact wrench or the like.

As a method of discriminating the direction of the stud bolts which are aligned and conveyed from the parts feeder, a method of measuring the screw pitch of the screw portions at both ends and a method of projecting light from the fixed direction on the outer periphery of the stud bolt and measuring the reflected light amount thereof. A method of measuring with a photoelectric sensor is known. In the former method, the direction of the stud bolt at the fixed position is determined by measuring the screw pitch of the threaded portions at both ends of the stud bolt held at the fixed position and determining the size. The latter method uses the fact that the outer circumference of the stud bolt shaft has less unevenness, and the amount of light reflected from this is greater than the amount of light reflected from the screw with many unevenness. Determine.

[0004]

A method of determining the direction of the stud bolt by measuring the screw pitch of the threaded portions at both ends of the stud bolt is to determine the direction if the stud bolt has a large screw pitch difference between the threaded portions at both ends. Can be relatively accurate. However, many types of stud bolts have a small screw pitch difference of 1 mm or less between the threaded portions at both ends, and it is difficult to accurately detect the screw pitch. Therefore, the direction of the stud bolt can be accurately determined by measuring the screw pitch. There was a problem that there were many missing and erroneous judgments. In addition, the method of determining the direction of the stud bolt by measuring the screw pitch cannot be applied to stud bolts having the same screw pitch at the screw portions at both ends, and thus has a problem of lacking versatility.

A method of detecting the difference in the amount of light reflected from the shaft portion of the stud bolt and the outer circumference of the screw portion by a photoelectric sensor to determine the direction of the stud bolt is a stud bolt in which the screw pitch at both ends is the same. However, if dust adheres to the stud bolt, the photoelectric sensor may malfunction due to the dust. Actually, the stud bolts are sent to the position determination position while aligning with the parts feeder, and are held in this position for direction determination, but powder dust is attached to the stud bolts while being aligned and conveyed by the parts feeder. However, this dust may be transferred to the eyes of the photoelectric sensor at the direction determination position, resulting in a decrease in the sensitivity of the photoelectric sensor, and the photoelectric sensor may malfunction to make it impossible to accurately determine the direction of the stud bolt.

The object of the present invention is to provide stud bolts with a large and small pitch, regardless of whether dust is attached or not.
It is an object of the present invention to provide a method for always discriminating the direction of a stud bolt with high reliability and a device for discriminating the direction thereof.

[0007]

The method of the present invention is a method of discriminating the directions of stud bolts having different lengths of the first screw portion and the second screw portion on both sides of the shaft portion by the difference in the length of each screw portion. , The direction of the stud bolt supplied to the fixed position is positive or 1
Regardless of the opposite direction of 80 °, the stud bolt shaft portion and the first screw portion or the second screw portion come into close contact with each other from two air holes at fixed positions and the corresponding shaft portion and the first screw hole. By blowing air from the same air supply source toward the screw part or the second screw part and judging the magnitude of the air pressure at the two air holes, by judging the direction of the stud bolt at a fixed position, To achieve the above objectives.

The device of the present invention is a device for discriminating the direction of stud bolts having different lengths of the first screw portion and the second screw portion on both sides of the shaft portion by the difference in the lengths of the respective screw portions. It is formed at two predetermined positions on the bolt holding portion that holds the stud bolt and on the surface of the bolt holding portion that closely approaches and faces the outer circumference of the stud bolt. When facing the shaft portion, the other faces the first screw portion or the second screw portion of the stud bolt, and a first air hole for blowing air from a fixed direction to the shaft portion and the first screw portion or the second screw portion, respectively. A direction discriminator having a second air hole, an air chamber communicating with each of the air holes of the direction discriminator, and a first direction air hole of the direction discriminator which is arranged so as to be reciprocally movable in a predetermined direction in the air chamber. First air communicating with The communicating with the compartment and the second air hole 2
A movable body that is divided into two air compartments and is displaced in the air compartment according to the air pressure difference in each air compartment, and a direction detector having a sensor that detects the displacement direction of the movable body, and the first air of the direction detector. It is characterized in that the compartment and the second air compartment are provided with an air supply source for supplying air of the same pressure.

[0009]

[Operation] With the shaft of the stud bolt held in place,
If air from the same air supply source is blown from two air holes at fixed positions on one of the screw parts on both sides of the shaft, the amount of air leaking from the air holes corresponding to the shaft with less unevenness is large. The amount of air leaked from the air hole corresponding to the screw part is smaller, the air pressure of the air hole on the shaft side is higher than the air pressure of the air hole on the screw part, and the air pressure of both air holes can be determined. Then, the direction of the stud bolt at the fixed position is determined. The size of the air pressure in the air holes at the two fixed positions can be accurately and accurately detected by moving the movable body such as the piston rod of the air cylinder by the difference in the air pressure between the air holes. It is executed with high reliability.

Further, two air holes are provided at fixed positions of the direction discriminator for holding the stud bolt in a fixed position, and a direction detector for detecting the magnitude of the air pressure in these two air holes is separate from the direction discriminator. By providing it on the body, a sensor that outputs a stud bolt direction detection signal can be installed in the direction detector, and there is no concern that the function of the sensor will be damaged by the stud bolt, and the stud bolt direction determination operation of the sensor will be stable. Further, the structure of the direction discriminator having no sensor is simplified, and a fixed type for the direction discriminator or a rotary type for reversing the direction of the stud bolt can be arbitrarily used.

[0011]

EXAMPLES Examples will be described below with reference to the drawings.

1 (a) and 1 (b) are sectional views of a main part of a stud bolt direction discriminating device. The direction discriminating device shown in FIG. 1 is a direction discriminating body 3 for holding a stud bolt 1 in a fixed position.
And a direction detector 7 for detecting the direction of the stud bolt 1 held by the direction discriminator 3, and an air supply source 9 for supplying air 8 to the direction detector 7 and the direction discriminator 3. The stud bolt 1 integrally has a first screw portion 1b and a second screw portion 1c on both sides of a substantially central shaft portion 1a. In the drawing, the first
Although the length of the screw portion 1b is shorter than the length of the second screw portion 1c, the length may be reversed.

The directional discriminator 3 includes a bolt holding portion 4 for holding the stud bolt 1 in a fixed position, and first air holes 2a and second air holes 2 provided at two fixed positions of the bolt holding portion 4.
b. The bolt holding portion 4 is a bolt insertion hole, a bolt fitting groove, a chuck or the like for holding the stud bolt 1 at a fixed position in the length direction thereof, and is provided at the center of the block-shaped direction discriminator 3 as shown in FIG. 1, for example. It is composed of a discriminating hole 5 which is opened at both ends and a stopper 6 which is fixed to one end of the discriminating hole 5 or is detachably arranged. The discrimination hole 5 has an inner diameter slightly larger than the outer diameter of the stud bolt 1 and has a length substantially equal to the entire length of the stud bolt 1. The tip of the stud bolt 1 inserted into the discrimination hole 5 through the opening opposite to the stopper 6 of the discrimination hole 5 contacts the stopper 6,
It is held at a fixed position in the discrimination hole 5.

Incidentally, as shown in FIG. 1 (a), the direction when the stud bolt 1 is inserted into the discrimination hole 5 with the first screw portion 1b at the head is, for example, the forward direction, and is shown in FIG. 1 (b). As described above, the direction in which the second screw portion 1c is inserted at the top is the reverse direction. Further, the direction discriminating body 3 is a movable type which rotates or the like as described in FIGS. 3 and 4, or a fixed type which is described in FIG. 5, and its use will be described later.

The first air holes 2 are provided at two locations on the inner peripheral surface of the discrimination hole 5.
a and the second air hole 2b are formed. As shown in FIG. 1A, when the stud bolt 1 held in the determination hole 5 is in the forward direction, the first air hole 2a is located at a fixed position close to and facing the shaft portion 1a of the stud bolt 1 and the second air hole 2a. The air hole 2b is formed at a fixed position that is close to and faces the second screw portion 1c of the stud bolt 1. Further, as shown in FIG. 1B, when the stud bolt 1 held in the determination hole 5 is in the opposite direction, the first air hole 2a is close to the second screw portion 1c of the stud bolt 1 and is a fixed position facing the second screw portion 1c. In addition, the second air hole 2b is formed at a fixed position that is close to and opposed to the shaft portion 1a of the stud bolt 1.

The direction detector 7 detects the forward and reverse directions of the stud bolt 1 held by the direction discriminator 3 in the respective air holes 2a, 2a.
It is detected by the air pressure difference of b. Each air hole 2
For example, an air cylinder 11 having an air chamber 10 communicating with a and 2b, a movable body piston 12 arranged in the air chamber 10, and a sensor 14 for detecting the displacement direction of the piston 12 are provided. The air chamber 10 of the air cylinder 11 is divided into a first air compartment 10a and a second air compartment 10b by a piston 12, and the first air compartment 10a and the first air hole 2a of the direction discriminator 3 are connected to each other by piping. The 2 air compartment 10b and the 2nd air hole 2b of the direction discriminating body 3 are connected by piping. Piston rod 1 integrated with piston 12
Reference numeral 3 penetrates the side walls of the air compartments 10a and 10b so as to be movable in the axial direction.

Each air compartment 10 of the air cylinder 11
A constant pressure air 8 is supplied from an air supply source 9 common to both a and 10b. The piston rod 13 is displaced by the air pressure difference between the air compartments 10a and 10b, and the sensor 14 detects the direction of this displacement. The sensor 14 is a photoelectric sensor, a proximity switch, or the like, and is arranged at a fixed position so as to detect the presence or absence of the piston rod 13 protruding from the second air compartment 10b.

The direction determination of the stud bolt 1 by the direction determination device of FIG. 1 is performed as follows.

When one stud bolt 1 is automatically supplied to the discrimination hole 5 of the direction discriminator 3 from the outside by a parts feeder or the like, a constant pressure air 8 is supplied from the air supply source 9 to the air compartments 10a, 10b of the air cylinder 11. It is supplied to each air hole 2a, 2b of the direction discriminator 3 through.

When the stud bolt 1 is in the positive direction in the discrimination hole 5 of the direction discriminator 3 as shown in FIG. 1 (a), the air 8 is blown from the first air hole 2a to the shaft portion 1a of the stud bolt 1. Then, the air 8 is blown to the second screw portion 1c from the second air hole 2b. Since the outer circumference of the shaft portion 1a is a surface with little unevenness, the amount of air 8 blown from the first air hole 2a is small, and the outer circumference of the other second screw portion 1c is the uneven surface of ridges and valleys of screws. Therefore, the leak amount of the air 8 blown from the second air hole 2b is large. Therefore, the air pressure in the first air hole 2a becomes larger than the air pressure in the second air hole 2b, and the piston 12 of the air cylinder 11 has a small air pressure due to the difference in air pressure between the two.
It moves in the direction of the air compartment 10b. A sensor 14 is arranged at the tip of the moved piston rod 13, the sensor 14 detects the piston rod 13, and outputs a rod presence detection signal to a direction determination circuit (not shown). The direction discriminating circuit uses the rod presence detection signal from the sensor 14 so that the shaft portion 1a of the stud bolt 1 in the direction discriminating body 3 is in the direction of the first air hole 2a and the stud bolt 1 is in the positive direction. To determine.

Further, when the stud bolt 1 is in the opposite direction in the discrimination hole 5 of the direction discriminator 3 as shown in FIG. 1B, the second screw portion 1c of the stud bolt 1 is provided with the first air hole 2a. The air 8 is blown and the second air hole 2 is formed in the shaft portion 1a.
Air 8 is blown from b. In this case, the leak amount of the air 8 blown from the first air hole 2a is large,
The amount of leakage of the air 8 blown from the second air hole 2b decreases, and the air pressure of the first air hole 2a becomes smaller than the air pressure of the second air hole 2b. Therefore, the piston 12 of the air cylinder 11 moves toward the first air compartment 10a having a small air pressure, and the piston rod 13
The tip end of the is separated from the sensor 14, and the sensor 14 detects the absence of the rod. The direction determination circuit determines that the shaft portion 1a of the stud bolt 1 in the direction determination body 3 is in the direction of the second air hole 2b and that the stud bolt 1 is in the opposite direction based on the rod-free detection signal.

Even if the air pressure difference between the air holes 2a and 2b for discriminating the direction of the stud bolt 1 in the direction discriminating body 3 is small, this air pressure difference is clearly shown by the displacement of the piston 12 of the air cylinder 11. Since the air pressure difference is amplified by the displacement amount of the piston 12, the direction of the stud bolt 1 can be discriminated accurately and surely. Further, since the air 8 is blown to the direction determining body 3, even if dust is attached to the stud bolt 1, the dust is blown off by the blowing of the air 8 and the malfunction due to the dust is eliminated.

Further, since the sensor 14 for detecting the direction of the stud bolt 1 is installed at a fixed position of the direction detector 7 which is separate from the direction discriminator 3 which holds the stud bolt 1, the sensor 14 is dusted. The sensor 14 can be placed in a stable environment where no generation occurs, the sensitivity of the sensor 14 can be stabilized, and highly accurate direction determination operation can be performed. Further, since the direction discriminator 3 and the direction detector 7 are connected separately from each other by piping, the direction discriminator 3 can be conveniently applied to both movable and fixed type.

The embodiment shown in FIG. 2 uses a diaphragm 15 for the direction detector 7. Diaphragm 15
Divides one container into a first air compartment 10a and a second air compartment 10b by a movable diaphragm 16. This first air compartment 10a communicates with the first air hole 2a,
The air compartment 10b communicates with the second air hole 2b, and a constant pressure air 8 is supplied from the air supply source 9 to each of the air compartments 10a and 10b. The piston rod 17 fixed to the central portion of the diaphragm 16 penetrates the side wall of the second air compartment 10b and is projected to the outside, and the sensor 14 is moved within the range of movement of its tip.
Is fixedly placed.

When the stud bolt 1 inserted in the discrimination hole 5 of the direction discriminator 3 is in the normal direction, the first air hole 2a and the first air hole 2a
The air pressure in the air compartment 10a is equal to that of the second air hole 2b.
It becomes larger than the air pressure of the air compartment 10b, the diaphragm 16 of the diaphragm 15 bulges toward the second air compartment 10b side, the tip of the piston rod 17 is detected by the sensor 14, and it is determined that the stud bolt 1 is in the normal direction. To be done.
When the stud bolt 1 held in the discrimination hole 5 is in the reverse direction, the air pressure of the first air compartment 10a of the diaphragm 15 becomes smaller than the air pressure of the second air compartment 10b, and the diaphragm 16 is shown by the chain line in FIG. First air branch 1
0a side, the tip portion of the piston rod 17 is disengaged from the sensor 14, and it is determined that the stud bolt 1 is in the reverse direction.

Next, a specific application example of the direction discriminating apparatus will be described with reference to FIGS. 3 to 5.

The direction discriminating apparatus shown in FIG.
The movable directional discriminator 3 is arranged in the bolt transport path 22 between the zero and the bolt automatic assembly machine 21. The stud bolts 1 are aligned in a line in the axial direction in the bolt transport path 22, and the direction discriminator 3 can be rotated by 90 ° in the reverse direction in a cylindrical housing 23 fixed to a substantially horizontal part of the bolt transport path 22. Is located in. The housing 23 has a bolt supply hole 24 connected to the parts feeder 20 on the side and a bolt discharge hole 25 connected to the automatic bolt assembling machine 21 on the lower side.

With one end opening of the discrimination hole 5 of the direction discriminator 3 aligned with the bolt supply hole 24, the parts feeder 20
One stud bolt 1 sent from the machine is the discrimination hole 5
Is supplied to. At this time, the portion of the housing 23 facing the bolt supply hole 24 identifies the stud bolt 1 as the discrimination hole 5.
It functions as a stopper that holds it in place.

When the stud bolt 1 in the discriminating hole 5 is discriminated to be in the normal direction, the direction discriminating body 3 is rotated 90 ° in the positive direction indicated by the solid arrow in FIG.
Is dropped in the bolt discharge hole 25 by its own weight and supplied to the automatic bolt assembly machine 21. When the stud bolt 1 in the discriminating hole 5 is discriminated to be in the reverse direction, the direction discriminating body 3 rotates 90 ° in the direction opposite to the chain line arrow in FIG. Then, the bolt discharge hole 25 falls by its own weight and is supplied to the automatic bolt assembly machine 21.

The direction discriminating apparatus shown in FIG.
The movable direction discriminator 3 is arranged in a housing 26 fixedly arranged in a substantially vertical part of the bolt conveying path 22 between 0 and the automatic bolt assembly machine 21 so as to be rotatable forward and backward by 180 °. The housing 26 has a bolt supply hole 27 and a bolt discharge hole 28 at the upper and lower facing portions.

With the upper end opening of the discrimination hole 5 of the direction discriminator 3 aligned with the bolt supply hole 27, the parts feeder 20
One stud bolt 1 sent from the machine is the discrimination hole 5
And is held in place by the stopper 6. When the stud bolt 1 in the discrimination hole 5 is discriminated to be in the forward direction, the direction discriminator 3 does not rotate and only the stopper 6 is opened, so that the forward direction stud bolt 1 in the discrimination hole 5 is discharged into the bolt discharge hole. 28 is dropped by its own weight, and the bolt automatic assembly machine 21
Is supplied to. When the stud bolt 1 in the discrimination hole 5 is discriminated to be in the reverse direction, the direction discriminator 3 is rotated by 180 °, the stud bolt 1 in the discrimination hole 5 is in the positive direction, and the bolt discharge hole 28 is loaded by its own weight. It is dropped and supplied to the bolt automatic assembly machine 21.

The direction discriminating device shown in FIG.
The fixed direction discriminator 3 and the bolt direction reversing device 30 are arranged directly under the bolt conveying path 22 between the 0 and the bolt automatic assembly machine 21 in a substantially vertical part. The bolt direction reversing device 30 includes a determination hole 5 in the vertical direction of the fixed direction determination body 3.
It has a movable reversing plate 31, a reversing block 32, and a reversing space 33, which are arranged in the middle of a bolt conveying path 22 ′ provided below.

In the apparatus shown in FIG. 5, when the stud bolt 1 in the discriminating hole 5 of the fixed direction discriminator 3 is discriminated to be in the normal direction, the reversing plate 31 is disengaged from the bolt conveying path 22 'and the lower end of the discriminating hole 5 is detected. The stopper 6 is opened, and the forward stud bolt 1 drops on the bolt transport path 22 ′ by its own weight and is supplied to the automatic bolt assembly machine 21. Further, when the stud bolt 1 in the discrimination hole 5 of the fixed direction discriminating body 3 is discriminated to be in the reverse direction, the stopper 6 is opened while the reversing plate 31 is projected to the bolt conveying path 22 ′, and the discrimination hole 5 by its own weight. The tip of the falling reverse stud bolt 1 hits the reversing plate 31, and the reversing plate 3
It falls to the reversal space 33 with 1 as a fulcrum. The stud bolt 1 that has fallen into the reversal space 33 is guided by the reversal block 32 and reversed in the forward direction as shown by the chain line in FIG.
As it is, it is dropped onto the bolt transport path 22 ′ and supplied to the automatic bolt assembly machine 21.

[0034]

As in the method of the present invention, air from the same air supply source is blown from the air holes at the two fixed positions to the shaft portion of the stud bolt held at the fixed position and one of the screw portions on both sides of the shaft portion. Due to the difference in the amount of air leaked from the shaft and screw, the air pressure in the air hole on the shaft side becomes higher than the air pressure in the air hole on the screw side, and the air pressure in both air holes can be determined. The direction of the stud bolt at the fixed position can be accurately determined, and the size of the air pressure in the air holes at the two fixed positions can be determined by the difference in the air pressure between the two air holes. By moving the, the stud bolt can be detected reliably and the stud bolt direction determination accuracy is high and stable.

In addition, the direction discriminator for holding the stud bolt in a fixed position and the direction detector for detecting the magnitude of the air pressure in the two air holes of the direction discriminator are provided separately, so that the direction of the stud bolt can be changed. The sensor that outputs the detection signal is installed on the direction detector side in a stable environment where dust is not generated, the function of the sensor is stabilized, and the reliability of the direction determination of the stud bolt is improved. Moreover, it is only necessary to provide air holes in the direction discriminator, and it becomes easy to use a fixed type or a rotary type that reverses the direction of the stud bolts. A discriminating device can be provided.

[Brief description of drawings]

FIG. 1A and FIG. 1B are sectional views of a main part of a stud bolt direction discriminating apparatus showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a stud bolt direction discriminating device showing a second embodiment of the invention.

FIG. 3 is a front view of a main part showing an outline of a first stud bolt automatic alignment supply mechanism using the apparatus of FIG. 1 or FIG.

FIG. 4 is a front view of the essential part showing the outline of a second stud bolt automatic alignment supply mechanism using the apparatus of FIG. 1 or FIG.

FIG. 5 is a front view of a main part showing an outline of a third stud bolt automatic alignment supply mechanism using the apparatus of FIG. 1 or FIG.

[Explanation of symbols]

 1 Stud bolt 1a Shaft part 1b First screw part 1c Second screw part 2a First air hole 2b Second air hole 3 Direction discriminator 4 Bolt holding part 7 Direction detector 8 Air 9 Air supply source 10 Air chamber 10a 1st Air compartment 10b Second air compartment 12 Movable body (piston) 14 Sensor 16 Movable body (diaphragm diaphragm)

Claims (2)

[Claims] 1. A stud bolt supplied to a fixed position by a method of discriminating the direction of a stud bolt having different lengths of a first screw portion and a second screw portion on both sides of a shaft portion by the difference in the length of each screw portion. Regardless of whether the direction is normal or opposite to 180 °, it is possible to handle from two air holes at fixed positions that are close to and face the shaft part of the stud bolt and the first screw part or the second screw part, respectively. The direction of the stud bolt at a fixed position is determined by blowing air from the same air supply source toward the shaft and the first screw part or the second screw part, and determining the magnitude of the air pressure in the two air holes. A method for determining the direction of a stud bolt, which is characterized by determining. 2. A device for determining the direction of a stud bolt having different lengths of the first screw portion and the second screw portion on both sides of the shaft portion by the difference in the length of each screw portion, and holding the stud bolt in a fixed position. It is formed at two predetermined positions on the bolt holding portion and on the surface of the bolt holding portion that closely approaches and faces the outer periphery of the stud bolt. One of the stud bolts can be oriented in either the forward direction or the 180 ° opposite direction. When the shaft portion of the stud bolt is opposed, the other is opposed to the first screw portion or the second screw portion of the stud bolt, and air is blown to the shaft portion and the first screw portion or the second screw portion from a fixed direction, respectively. A direction discriminator having an air hole and a second air hole, an air chamber communicating with each air hole of the direction discriminator, and arranged in the air chamber so as to be reciprocally movable in a predetermined direction. Connect to 1 air hole A movable body that is bisected into a second air compartment that communicates with the first air compartment and a second air hole of the direction discriminator and that displaces the air compartment according to the air pressure difference between each air compartment, and the displacement direction of the movable body. A direction detector having a sensor for detecting the direction, and an air supply source for supplying the same pressure air to the first air compartment and the second air compartment of the direction detector apparatus.