JP2009274793A - Position detecting device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detecting device on a movable device having a movable part guided by a guide shaft, for detecting whether the movable part exists on a reference position or not. <P>SOLUTION: An air sensor 30 (the position detecting device) includes a top 18, a bush 40, an air flow path 28, and a pressure gauge 26. The top 18 is provided on the guide shaft 12 in an approximately coaxial manner, has a large diameter portion 18a having a larger diameter than the guide shaft 12, and is rockingly supported on the guide shaft 12. The bush 40 having a through-hole 42 is fixed to a position where the large diameter portion 18a of the top 18 enters into the through-hole 42 when the movable part 10 reaches the reference position. The air flow path 28 supplies air (fluid) from the outside into the through-hole 42. The pressure gauge 26 monitors the pressure of the air. A lifter device 2 uses the air sensor 30 for accurately detecting the position of the movable part 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a position detection device. In particular, the present invention relates to a position detection device using a pressurized fluid.

  A movable device having a movable portion is known. In such a movable device, a sensor (position detection device) that detects whether or not the movable portion is present at the reference position may be used when the movable portion is moved to the reference position. This type of sensor includes a contact sensor that confirms the presence of a movable part by contact, an optical sensor that confirms the presence of a movable part by the presence or absence of an optical signal, and the presence of a movable part by a change in the pressure of pressurized air. Air sensors to check are known. Patent Documents 1 to 3 describe devices using various air sensors.

Japanese Utility Model Publication No. 7-636 JP 2006-255849 A Japanese Utility Model Publication No. 6-74207

In a movable device having a movable part guided by a guide shaft, an air sensor for detecting whether or not the movable part is present at a reference position may be configured as follows. That is, a piece having a diameter larger than that of the guide shaft and a bush having a through hole capable of accommodating the piece are prepared, the piece is fixed substantially coaxially to the guide shaft, and the piece is moved when the movable portion reaches the reference position. The bush is fixed at a position where it enters the through hole. And while supplying pressurized air to the through-hole of a bush, the pressure of the pressurized air is monitored.
In this air sensor, when the movable part moves to the reference position, the piece fixed to the guide shaft enters the through hole of the bush. In the through hole before the top enters, there is sufficient space for the pressurized air supplied to the inside of the through hole to be discharged to the outside of the through hole, and the pressure of the pressurized air is relatively low. Kept low. When the piece enters the through hole of the bush, the clearance between the through hole and the large diameter portion of the piece becomes narrow, and the pressure of the pressurized air increases. Therefore, by monitoring this change in pressure, it is possible to detect the timing at which the top has entered the through-hole of the bush, that is, the timing at which the movable portion has reached the reference position.

In a movable device, the axis | shaft of the guide shaft which guides a movable part may incline because of the reason that the biased load is applied to a movable part. In this case, the axial position of the guide shaft is displaced with respect to the bush. When the piece enters the through hole of the bush, the piece may interfere with the bush, and the movement of the movable part may be hindered.
In order to prevent the above-described phenomenon, it is conceivable that the through hole formed in the bush is formed large enough to prevent the movement of the movable part in consideration of the amount of displacement of the axial position of the guide shaft. According to this method, even when the guide shaft is inclined with respect to the bush, the top can be surely entered into the through hole. However, if the through hole is formed relatively large with respect to the top, even when the top enters the through hole of the bush, a relatively large clearance is formed between the through hole and the top. When the piece enters the through hole, the change in the pressure of the pressurized air becomes small, and it may not be possible to detect that the movable part has reached the reference position.

  The present invention solves the above problems. That is, the present invention provides an air sensor (position detection device) that can smoothly move a top into a through-hole even when the guide shaft is inclined and can accurately detect the position of the movable portion. It is an object.

The present invention is embodied in a position detection device that is provided in a movable device having a movable portion guided by a guide shaft and detects whether or not the movable portion is present at a reference position. This position detection device includes a top, a bush, a fluid flow path, and a monitoring device.
The top is provided substantially coaxially with the guide shaft, has a large diameter portion that is larger in diameter than the guide shaft, and is supported to be swingable with respect to the guide shaft. The position where the top is provided on the guide shaft is not particularly limited. A frame may be provided at the center of the guide shaft or may be provided at the end.
The bush has a through hole, and is fixed at a position where the large diameter portion of the top enters the through hole when the movable portion reaches the reference position. The object to which the bush is fixed is not particularly limited. When the guide shaft is fixed to the movable portion and moves together with the movable portion, the bush is fixed to a stand that does not move by the moving mechanism. When the guide shaft is fixed to the gantry, the bush is fixed to the movable part.
The fluid channel supplies a fluid supplied from the outside into the through hole. Here, the “fluid” is not limited to air but includes all materials such as gas, liquid, and gel whose pressure change can be monitored. The fluid flow path includes at least one of a flow path for supplying fluid to the movable device from the outside and a flow channel for supplying fluid to the through hole in the movable device.
The monitoring device monitors the pressure of the fluid. The place for monitoring the pressure of the fluid is not particularly limited. For example, the pressure of the fluid in the fluid flow path may be monitored, or the pressure of the fluid in the through hole may be monitored.

  In this position detection device, the top is supported to be swingable with respect to the guide shaft. Therefore, when the top enters the through hole of the bush, the top can change its inclination along the through hole of the bush. Even when the guide shaft is inclined with respect to the bush, the bush and the piece are prevented from strongly interfering with each other, and the piece can surely enter the through hole. Even if the clearance between the through hole of the bush and the large diameter portion of the top is relatively small, the movement of the movable portion is not hindered. By relatively reducing the clearance between the through hole of the bush and the large diameter part of the top, the amount of fluctuation appearing in the fluid pressure can be increased, and it is ensured that the movable part has reached the reference position. Can be detected.

In the above-described position detection device, it is preferable that the top is supported so as to be further radially displaceable with respect to the guide shaft.
According to the above structure, when the piece enters the through hole of the bush, the piece can change its position and posture more freely according to the position of the through hole. The clearance between the through hole of the bush and the large diameter portion of the top can be further reduced, and it is possible to reliably detect that the movable portion has reached the reference position.

In the above-described position detection device, it is preferable that a tapered portion is formed on at least one of the upper portion and the lower portion of the large diameter portion.
When the tapered portion as described above is formed, the top can be smoothly moved in accordance with the position of the through hole when the large diameter portion of the top moves into the through hole.

The present invention is also embodied in a position detection method for detecting whether or not the movable part of the movable device is present at the reference position. This position detection method includes at least the following four steps.
(1) A step of providing a top having a larger diameter than the guide shaft so as to be swingable with respect to the guide shaft so as to be substantially coaxial with the guide shaft. (2) A through hole is formed. (3) a step of supplying a fluid supplied from the outside into the through hole when the movable part reaches the reference position (3) a step of supplying a fluid supplied from the outside into the through hole (4) a pressure of the fluid This method can also reduce the clearance between the through-hole and the large-diameter portion of the top, and reliably detect that the movable portion has reached the reference position.

  According to the present invention, the clearance between the through hole and the large-diameter portion of the top can be reduced, and it is possible to reliably and accurately detect that the movable portion has reached the reference position.

The main features of the embodiments described below are first organized.
(Characteristic 1) The bush is formed with a through flow passage for introducing pressurized air into the through hole. The through channel extends from the outer peripheral surface of the bush to the inner peripheral surface of the bush (that is, the through hole).
(Feature 2) The top is provided at the end of the guide shaft.
(Feature 3) The bush is fixed to a shaft holder that slidably supports the guide shaft.

(First embodiment)
Embodiments embodying the present invention will be described with reference to the drawings. FIG. 1 shows a lifter device 2 (movable device) of this embodiment. The lifter device 2 is a device that moves the workpiece 16 placed on the movable unit 10 to a reference position. The lifter device 2 is provided with an air sensor 30. The air sensor 30 is a position detection device that detects whether or not the movable portion 10 of the lifter device 2 is present at the reference position.

As shown in FIG. 1, the lifter device 2 includes a gantry 4, a hydraulic cylinder 6, a movable part 10, guide shafts 12 and 14, and shaft holders 32 and 34.
The hydraulic cylinder 6 is an actuator for moving the movable part 10 up and down. The hydraulic cylinder 6 is fixed to the gantry 4. The hydraulic cylinder 6 is connected to a hydraulic unit via a hydraulic pipe (not shown). The hydraulic cylinder 6 receives supply of pressurized oil from the hydraulic unit and moves the cylinder rod 8 up and down in the vertical direction of FIG. A movable portion 10 is fixed to the end of the cylinder rod 8, and the movable portion 10 moves up and down as the cylinder rod 8 moves up and down.

The plurality of guide shafts 12 and 14 are fixed to the back surface 10 a of the movable portion 10. The plurality of guide shafts 12 and 14 extend parallel to each other toward the gantry 4. The shaft holders 32 and 34 are fixed to the gantry 4 and support the guide shafts 12 and 14 slidably, respectively. Thereby, the movable part 10 is guided by the guide shafts 12 and 14 and can move up and down with respect to the gantry 4.
The shaft holder 32 has a through hole 32a through which the guide shaft 12 passes. The shaft holder 32 supports the guide shaft 12 so as to be movable in the axial direction and immovable in the radial direction. A sleeve 36 is provided in the through hole 32 a of the shaft holder 32.
The shaft holder 34 has a through hole 34a through which the guide shaft 14 passes. The shaft holder 34 supports the guide shaft 14 so as to be movable in the axial direction and immovable in the radial direction. A sleeve 38 is provided in the through hole 34 a of the shaft holder 34.

The air sensor 30 includes a top 18, a bush 40, an air flow path 28, and a pressure gauge 26 (an example of a monitoring device).
The top 18 is provided on the end surface 12 a of the guide shaft 12. The top 18 is positioned substantially coaxially with the guide shaft 12. The top 18 includes large diameter portions 18 a and 18 b that are larger in diameter than the guide shaft 12. As will be described in detail later, the top 18 can be displaced in the axial direction and the radial direction with respect to the guide shaft 12 and is supported so as to be swingable with respect to the guide shaft 12.
The bush 40 is provided below the shaft holder 32. The bush 40 is supported substantially coaxially with the shaft holder 32. A through hole 42 having a diameter larger than that of the large diameter portion 18 a of the top 18 is formed at the center of the bush 40. The guide shaft 12 extends through the through hole 42 of the top 18. The bush 40 is formed with a through channel 44 extending from the outer peripheral surface 40 a to the through hole 42. A fluid outlet 48 that opens to the through hole 42 is formed at a position where the through flow path 44 reaches the through hole 42.

An air flow path 28 is connected to the through flow path 44 of the bush 40. The air flow path 28 is connected to a pressurized air source 24 provided outside the lifter device 2. The pressurized air source 24 supplies air (an example of a fluid) pressurized to the through hole 42 from the fluid outlet 48 via the air channel 28 and the through channel 44. The through passage 44 constitutes a part of the air passage 28 that supplies pressurized air to the through hole 42. The bush 40 may be provided with one through channel 44 or a plurality of through channels 44. That is, the bush 40 may be provided with one fluid outlet 48 or a plurality of fluid outlets 48.
The pressure gauge 26 is provided in the air flow path 28. The pressure gauge 26 measures the pressure of the pressurized air flowing through the air flow path 28. As will be described in detail later, the air sensor 30 detects whether or not the movable unit 10 has reached the reference position based on a change in the measurement value by the pressure gauge 26.

FIG. 2 shows an enlarged connection portion between the guide shaft 12 and the top 18. With reference to FIG. 2, the attachment structure to the guide shaft 12 of the top 18 is demonstrated.
The top 18 is fixed to the guide shaft 12 using a stopper 46. A tap hole 13 is formed in the end surface 12 a of the guide shaft 12. The top 18 is formed with a through hole 19a penetrating from the upper surface 18c to the lower surface 18d. A counterbore 19b having a larger diameter than the through hole 19a is formed below the through hole 19a of the top 18. The stopper 46 is formed with a screw portion 46 a that is screwed into the tap hole 13 formed in the guide shaft 12. The stopper 46 is formed with a main shaft portion 46b that is continuous with the screw portion 46a. The main shaft portion 46b has a smaller diameter than the through hole 19a of the top 18, and is longer than the through hole 19a. Further, the stopper 46 is formed with an umbrella portion 46c continuous with the main shaft portion 46b. The umbrella part 46c has a larger diameter than the through hole 19a, a smaller diameter than the counterbore part 19b, and is formed to have a length substantially the same as the depth of the counterbore part 19b.
1 to 6, for convenience of explanation, the gaps between the top 18 and the stopper 46 and between the top 18 and the guide shaft 12 are illustrated in an enlarged manner.

  As described above, the through hole 19a of the top 18 is formed shorter than the main shaft portion 46b of the guide shaft 12. Accordingly, the top 18 is supported so as to be movable in the axial direction with respect to the guide shaft 12. The through hole 19a of the top 18 is formed with a larger diameter than the main shaft portion 46b of the guide shaft 12, and the counterbore portion 19b of the top 18 is formed with a larger diameter than the umbrella portion 46c of the guide shaft 12. ing. Accordingly, the top 18 is supported so as to be movable in the radial direction with respect to the guide shaft 12. Further, since the top 18 is supported with a gap in the axial direction and the radial direction with respect to the guide shaft 12, the top 18 is supported to be swingable with respect to the guide shaft 12.

The operation of the lifter device 2 will be described with reference to FIGS.
1 and 2 show a state in which the cylinder rod 8 of the hydraulic cylinder 6 is located at the lowest point (return limit) and the movable portion 10 is located at the lowest point. In this case, as shown in FIGS. 1 and 2, the guide shaft 12 is located in the through hole 42 of the bush 40. In this case, a relatively large clearance is formed between the through hole 42 of the bush 40 and the guide shaft 12. Therefore, the pressurized air supplied to the through hole 42 is discharged out of the through hole 42 without receiving a large resistance. In this state, the pressure of the pressurized air in the air flow path 28 is kept relatively low.

  When the hydraulic cylinder 6 raises the cylinder rod 8, the movable part 10 and the guide shafts 12 and 14 are raised accordingly. When the movable portion 10 moves to the reference position, the top 18 provided on the end surface 12a of the guide shaft 12 enters the through hole 42 of the bush 40 as shown in FIG. In this case, as shown in FIG. 4, the clearance D between the through hole 42 of the bush 40 and the large diameter portion 18a of the top 18 is narrower than the state shown in FIG. As a result, discharge of the pressurized air supplied to the through hole 42 is hindered, and the pressure of the pressurized air inside the air flow path 28 increases. The pressure gauge 26 monitors this change in pressure and detects that the movable portion 10 has moved to a reference position where the through hole 42 and the top 18 overlap. Thereby, the air sensor 30 can detect that the movable part 10 has moved to the reference position.

In the above-described operation, the guide shaft 12 may be tilted with respect to the shaft holder 32 due to a cause such as the work 16 being biased and placed on the movable portion 10. In this case, the position of the guide shaft 12 is displaced with respect to the shaft holder 32. As a result, as shown in FIG. 5, the large diameter portion 18 a of the top 18 supported by the guide shaft 12 interferes with the bush 40.
In the present embodiment, the top 18 is supported so as to be displaceable with respect to the guide shaft 12 with respect to the above event. Therefore, when the guide shaft 12 is inclined with respect to the shaft holder 32 and the frame 18 interferes with the bush 40, the frame 18 can change its position and posture (tilt). As shown in FIG. 6, the piece 18 that has interfered with the bush 40 is displaced in the horizontal direction while swinging with respect to the guide shaft 12 along the through hole 42 of the bush 40 (in the direction of the arrow 70). Accordingly, the top 18 enters in a posture that is substantially coaxial with the through hole 42. There is no need to increase the clearance between the inner wall of the through hole 42 and the large-diameter portion 18a of the top 18 unless the movement of the movable portion 10 is hindered. A highly accurate air sensor 30 can be realized.

In this embodiment, as shown in FIGS. 1 and 2, a tapered portion 18b is formed on the upper portion of the large diameter portion 18a of the top 18, that is, on the side entering the through hole 42 of the large diameter portion 18a. . In addition, since the taper part 18b is larger diameter than the guide shaft 12, it can be said that it is a part of the large diameter part 18a.
If the tapered portion 18b is formed on the upper portion of the large diameter portion 18a of the top 18, the tapered portion 18b interferes with the bush 40 before the large diameter portion 18a of the top 18 interferes with the bush 40. The frame 18 moves in the direction of the arrow 70. As a result, the top 18 can be smoothly moved to the through hole 42 of the bush 40.

(Second embodiment)
FIG. 7 shows a lifter device 102 of the second embodiment. In the lifter device 102, guide shafts 112 and 114 are fixed to the gantry 104, and shaft holders 132 and 134 are fixed to the movable portion 110. The other points are the same as those of the lifter device 2 of the first embodiment, and redundant description is omitted.
In FIG. 7, for convenience of explanation, the top 118 and the stopper 46 and the gap between the top 118 and the guide shaft 112 are enlarged.
In this embodiment, the top 118 is supported substantially coaxially on the guide shaft 112, is supported so as to be movable in the radial direction with respect to the guide shaft 112, and is supported so as to be swingable with respect to the guide shaft 112. ing. The bush 140 is supported substantially coaxially by the shaft holder 132, and a through hole 142 is formed at the center of the bush 140. In the lifter device 102 of the present embodiment, when the top 118 enters the through hole 142 due to the rise of the movable portion 110, the large diameter portion 118a of the top 118 and the bush 140 do not interfere strongly. The clearance between the large diameter portion 118a of the top 118 and the through hole 142 can be reduced. The air sensor 130 with high accuracy can be realized by the bush 140, the top 118, the air flow path 28, and the pressure gauge 26.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1 shows a lifter device 2 of a first embodiment. An enlarged view of the guide shaft 12 and the top 18 is shown. 1 shows a lifter device 2 of a first embodiment. An enlarged view of the guide shaft 12 and the top 18 is shown. It is a figure explaining the problem of a prior art. It is a figure explaining the effect of a present Example. The lifter apparatus 102 of 2nd Example is shown.

Explanation of symbols

2... Lifter device 4... Mount 6 .. hydraulic cylinder 8... Cylinder rod 10... Movable parts 12 and 14. ··· Tap hole 18 of guide shaft ··· Top 18a · Large diameter portion 18b · Top taper portion 19a · Through hole 19b · Top counterbore portion 24 ·· .... Air source 26 ... Pressure gauge 28 ... Air flow path 30 ... Air sensors 32, 34 ... Shaft holder 40 ... Bushing 42 ... Bushing through hole 44 ... Bushing through passage 46 ... Stopping tool

Claims (4)

A position detecting device that is provided in a movable device having a movable portion guided by a guide shaft and detects whether or not the movable portion exists at a reference position,
A top provided substantially coaxially with the guide shaft, having a large diameter portion larger than the guide shaft, and supported by the guide shaft so as to be swingable;
A bush formed with a through-hole, and when the movable portion reaches the reference position, the large-diameter portion of the top is fixed to a position where the through-hole enters.
A fluid flow path for supplying fluid supplied from the outside into the through hole;
A monitoring device for monitoring the pressure of the fluid;
A position detection device comprising:   The position detection device according to claim 1, wherein the frame is supported so as to be further radially displaceable with respect to the guide shaft.   The position detecting device according to claim 1, wherein a tapered portion is formed on at least one of an upper portion and a lower portion of the large diameter portion. In a movable device having a movable part guided by a guide shaft, a position detection method for detecting whether or not the movable part is present at a reference position,
Providing a top having a large diameter part larger than the guide shaft on the guide shaft so as to be swingable with respect to the guide shaft;
Fixing the bush in which the through hole is formed at a position where the top enters the through hole when the movable part reaches the reference position;
Supplying a fluid supplied from the outside into the through hole;
Monitoring the pressure of the fluid;
A position detection method comprising:

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