JP5358233B2 - Fluid leakage inspection device and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid leakage inspection device that accurately detects fluid leakage of a hydraulic device. <P>SOLUTION: The fluid leakage inspection device 100 is provided for a buffer 10 including an outer tube 11 in which a fluid chamber is defined by a piston slidably and internally inserted, and a piston rod 12 integrally formed with the piston and retractable with respect to the outer tube 11. The device includes a camera 30 for photographing a part to be inspected 12a on the fluid leakage of the buffer 10, a gas spraying device 40 which sprays gas on the part to be inspected 12a and changes an attaching state of a leaking fluid, an image comparison means for comparing images of the part to be inspected 12a when the gas is sprayed or is not sprayed by the gas spraying device 40, and a fluid leakage decision means for calculating a change between the two images by the image comparison means and determining the fluid leakage based on the change. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an inspection apparatus and an inspection method for detecting fluid leakage in a fluid pressure device.

  Conventionally, a fluid pressure device including a fluid chamber defined by a piston sliding inside a cylinder is known. This fluid pressure device is formed such that a viscous fluid is sealed inside a cylinder and the viscous fluid enters and exits the fluid chamber. A piston rod provided to protrude from the inside of the cylinder to the outside is connected to the piston.

  The sliding part between the cylinder and the piston rod is sealed so that viscous fluid does not leak. However, if viscous fluid leaks from the sliding part due to a defect in the production process, the function of the fluid pressure device may not be exhibited. For this reason, it is necessary to inspect the presence or absence of leakage of viscous fluid from the sliding portion in the production process.

  Patent Document 1 discloses an inspection method for a hydraulic damper that detects oil leakage using an oil leakage detection agent.

  In addition to the method of using a detection agent as in Patent Document 1, a method in which an operator visually inspects for the presence or absence of fluid leakage is widely used.

JP 2007-147019 A

  However, since the leaking viscous fluid is transparent, it may be overlooked by visual inspection. Further, in the visual inspection, the determination criteria vary depending on the operator, and therefore the determination varies. That is, it is difficult to maintain high inspection accuracy by visual inspection.

  Accordingly, an object of the present invention is to provide a fluid leakage inspection apparatus capable of accurately detecting leakage of viscous fluid.

  The present invention provides a fluid pressure device comprising: an outer tube in which a fluid chamber is defined by a piston slidably inserted; and a piston rod provided integrally with the piston and capable of moving forward and backward with respect to the outer tube. An apparatus for inspecting a fluid leakage of the fluid pressure device, the imaging means for capturing an image of the fluid leakage inspected part of the fluid pressure device, and a disturbance for imparting a disturbance to the inspected part and changing an adhesion state of the leaking fluid The change between the two images is calculated by the applying means, the image comparing means for comparing the images of the inspected part when the disturbance is applied by the disturbance applying means, and when the disturbance is not applied, and the image comparing means. And fluid leakage determining means for determining fluid leakage based on the change.

  In the present invention, the image comparison unit compares the captured image when the disturbance is applied to the inspected portion of the fluid pressure device with the captured image when no disturbance is applied. Then, a relative change between the two images is calculated, and fluid leakage is determined based on the change.

  Therefore, it is possible to obtain a fluid leakage inspection device that can detect fluid leakage with high accuracy.

1 is a configuration diagram of a fluid leakage inspection apparatus according to an embodiment of the present invention.

  Hereinafter, a fluid leakage inspection apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings.

  The fluid leakage inspection device 100 is a device for performing a fluid leakage inspection of the shock absorber 10.

  First, the shock absorber 10 which is the inspection target of the fluid leakage inspection apparatus 100 will be described with reference to FIG.

  The shock absorber 10 includes a substantially cylindrical outer tube 11 that forms a cylinder of the shock absorber 10, a piston (not shown) that is slidably disposed within the outer tube 11, and an outer tube 11 that is fixed to the piston. And a piston rod 12 projecting to the outside. This shock absorber 10 corresponds to a fluid pressure device. Instead of the shock absorber 10, a hydraulic cylinder in which the piston rod advances and retreats by the pressure of the liquid may be used.

  Inside the outer tube 11, two fluid chambers (not shown) are defined with a piston interposed therebetween. The two fluid chambers are filled with a viscous fluid such as oil.

  An orifice (not shown) through which viscous fluid can pass is formed in the piston. Since the viscous fluid can pass through the orifice, the piston can slide in the outer tube 11. Further, the shock absorber 10 exerts a damping force due to the resistance of the viscous fluid when moving between the two fluid chambers through the orifice.

  The piston rod 12 is provided coaxially with the central axis of the outer tube 11. The piston rod 12 is provided so as to freely enter and exit from the inside of one fluid chamber to the outside of the outer tube 11.

  The end of the outer tube 11 is sealed with a partition wall 11a. The piston rod 12 slides through the hole in the partition wall 11a.

  The partition wall 11a is provided with sealing means (not shown) in order to prevent the viscous fluid in the fluid chamber from leaking to the outside. That is, the sealing means prevents the viscous fluid from leaking between the hole of the partition wall 11a and the piston rod 12. This sealing means is, for example, an O-ring.

  The O-ring is fixed to the partition wall 11a and seals the fluid chamber. The outer tube 11 is filled with lubricating means such as grease to reduce the sliding resistance of the piston rod 12 so as to be supplied to the O-ring.

  A part of the piston rod 12 that advances and retreats with respect to the outer tube 11 is defined as a part to be inspected 12 a of the fluid leakage inspection apparatus 100. As long as the part 12a to be inspected is a part that slides on the inner periphery of the O-ring, a part in the longitudinal direction of the piston rod 12 may be arbitrarily set.

  When the piston rod 12 enters the fluid chamber, the viscous fluid sealed in the fluid chamber adheres to the portion to be inspected 12a. And the viscous fluid adhering to the to-be-inspected part 12a is removed by the O-ring when the piston rod 12 moves out of the fluid chamber, and does not leak to the outside of the fluid chamber. However, when the seal is not perfect due to a defect in the production process or the like, the viscous fluid may leak to the outside while adhering to the piston rod 12.

  Next, the fluid leakage inspection apparatus 100 will be described with reference to FIG.

  The fluid leak inspection apparatus 100 inspects the presence or absence of leakage of viscous fluid in the inspected portion 12a.

  The fluid leakage inspection apparatus 100 takes an image of an electric motor 20 for rotating the shock absorber 10 about its axis, an encoder 21 for measuring the rotation angle of the shock absorber 10, and an inspected portion 12 a of the piston rod 12. And a controller 50 for controlling the fluid leakage inspection apparatus 100. The camera 30 is configured to control the fluid leakage inspection apparatus 100.

  The electric motor 20 is provided so as to face the free end of the piston rod 12 and so that the rotation axis (not shown) coincides with the central axis of the shock absorber 10. The output shaft of the electric motor 20 is fixed to the free end of the piston rod 12. This electric motor 20 corresponds to the rotating means.

  The encoder 21 is provided to face the end of the outer tube 11. The encoder 21 is fixed to the end of the outer tube 11 so that the rotated shaft (not shown) coincides with the central axis of the shock absorber 10. This encoder 21 corresponds to the rotation angle detecting means.

  The encoder 21 measures the rotation angle of the shock absorber 10 rotated by the electric motor 20. The encoder 21 is electrically connected to the controller 50 and transmits the measured rotation angle of the shock absorber 10 to the controller 50.

  Instead of a configuration in which the encoder 21 and the electric motor 20 are provided separately, a configuration in which a motor provided with means for measuring a rotation angle, such as an AC servo motor or a stepping motor, may be used.

  The camera 30 is provided so as to face the piston rod 12 and perpendicular to the central axis of the piston rod 12. The camera 30 is provided at a predetermined distance from the piston rod 12. The predetermined distance is a distance at which the camera 30 can be focused, and is a distance that allows the camera 30 to image the entire portion to be inspected 12a. This camera 30 corresponds to an imaging means.

  The camera 30 can capture a still image of the part to be inspected 12 a of the piston rod 12. The camera 30 is electrically connected to the controller 50, operates in response to a command from the controller 50, and can transmit image data to the controller 50.

  The camera 30 can output images obtained by continuously capturing images. Specifically, the camera 30 captures a still image every predetermined time and forms one image by sequentially connecting the captured images. Thereby, the image which imaged the outer periphery of the outer tube 11 for one round can be output as one image.

  The predetermined time here is determined so as to be synchronized with the speed at which the shock absorber 10 is rotated by the electric motor 20. That is, the electric motor 20 rotates the shock absorber 10 at a rotation speed that matches the predetermined time. That is, the rotation speed of the electric motor 20 is adjusted by the controller 50 so that the rotation speed of the shock absorber 10 output from the encoder 21 and the predetermined time that is the interval at which the camera 30 captures a still image is synchronized. . Thereby, the camera 30 can image the part to be inspected 12 a over the entire circumference of the shock absorber 10.

  The camera 30 is provided with an illumination device 31 that illuminates the inspected part 12a. The lighting device 31 emits light in response to a command from the controller 50. The brightness of the illumination device 31 is arbitrarily adjusted to the brightness by the controller 50. The illumination device 31 is, for example, ring illumination attached around the lens of the camera 30.

  The gas blowing device 40 is provided to face the piston rod 12. In the present embodiment, the gas blowing device 40 is provided perpendicular to the central axis of the piston rod 12, but may not be perpendicular as long as gas can be blown onto the piston rod 12. The gas blowing device 40 is provided between the piston rod 12 and the camera 30.

  The gas blowing device 40 is provided so as not to enter the imaging range of the camera 30 and so as not to enter between the illumination device 31 that irradiates the inspected portion 12a and the inspected portion 12a. Therefore, in this embodiment, a hole is provided in the gas blowing device 40 so that the inspected portion 12a enters the imaging range of the camera 30 and enters the irradiation range of the illumination device 31.

  The gas spraying device 40 includes a plurality of small-diameter spraying ports (not shown) arranged linearly in parallel with the central axis of the piston rod 12, and sprays gas onto the part to be inspected 12a. The gas blowing device 40 is provided so that the longitudinal direction is parallel to the axis of the shock absorber 10. That is, the gas spraying device 40 can spray gas linearly along the axial direction of the piston rod 12. In addition to providing the gas spraying device 40, it is possible to change the adhesion state of the viscous fluid even if vibration is applied or ultrasonic waves collide.

  The controller 50 controls the fluid leakage inspection apparatus 100, and includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and I / O interface (input / output interface). It is composed of a microcomputer equipped. The RAM stores data in the processing of the CPU, the ROM stores a control program of the CPU in advance, and the I / O interface is used for input / output of information with the connected device. Control of the fluid leakage inspection apparatus 100 is executed by operating a CPU, RAM, or the like according to a program stored in the ROM.

  An image captured by the camera 30 and a signal from the encoder 21 are input to the CPU via the I / O interface. The CPU outputs a signal to the electric motor 20, the camera 30, and the lighting device 31 via the I / O interface.

  The controller 50 is provided with a display device 51. With this display device 51, it is possible to confirm the state of control in the controller 50. The display device 51 displays various information required by the operator, such as an image captured by the camera 30 and a fluid leakage determination result. A touch panel type monitor may be provided as the display device 51 to enable an operation by an operator.

  Hereinafter, a fluid leak inspection method using the fluid leak inspection apparatus 100 will be described.

  First, the shock absorber 10 is placed on the fluid leakage inspection apparatus 100 by the operator. In addition to being placed by an operator, it may be automated by providing placing means (not shown) such as a conveyor or a robot for placing the shock absorber 10 from equipment or the like (not shown) provided side by side. Good.

  With the outer tube 11 of the shock absorber 10 moved to the fluid leakage inspection apparatus 100 fixed, the piston rod is advanced and retracted several times in the outer tube 11. “Several times” means, for example, a few times. The length to be advanced and retracted is the length that the inspected part 12a completely enters the fluid chamber.

  When viscous fluid is leaking from the shock absorber 10, the viscous fluid adheres around the portion to be inspected 12 a in the piston rod 12 by this process. This step may be performed by an operator or may be automated and performed by equipment.

  Next, the rotating shaft of the electric motor 20 is fixed to the piston rod 12, and the rotated shaft of the encoder 21 is fixed to the outer tube 11. At this time, the piston rod 12 is fixed so as not to rotate relative to the outer tube 11. That is, the piston rod 12 and the outer tube 11 rotate together.

  Next, in a state where no gas is blown by the gas blowing device 40, the inspected portion 12 a is imaged using the camera 30 while illuminating the inspected portion 12 a by the illumination device 31. At this time, the shock absorber 10 is rotated by approximately one turn by the electric motor 20.

  The camera 30 captures an image for approximately one round of the outer circumference of the outer tube 11. Therefore, the image captured by the camera 30 is an image in which the outer periphery of the outer tube 11 is developed on a plane. That is, the width that can be captured by the camera 30 is the width of the image, and the circumference of the outer tube 11 is the height of the image. At this time, the position at the start of imaging and the position at the end of imaging are measured by the encoder 21 and stored together with the captured image in the RAM of the controller 50.

  Next, the inspected part 12a is imaged using the camera 30 in a state where gas is blown by the gas blowing device 40. At this time, the shock absorber 10 is rotated by approximately one turn by the electric motor 20. As for the imaging start position and the imaging end position, the positions stored in the RAM of the controller 50 are read, and imaging is performed so as to be the same position. In other words, the image is taken under the same conditions as the image taken without blowing the gas, except that the image is taken while blowing the gas. Thereby, the image imaged in the state which sprayed gas becomes the same width and height as the image imaged in the state which does not spray gas. The pixels at the same position in the two images are images of the same position of the inspected part 12a.

  Here, the electric motor 20 does not rotate the shock absorber 10 immediately after the gas blowing device 40 starts to blow the gas, but rotates the shock absorber 10 after waiting for a predetermined time. In order to start imaging after the adhesion state of the viscous fluid adhering to the outer peripheral surface of the inspected part 12a changes, it is better to wait for a predetermined time.

  The predetermined time is a minimum time required for the adhesive state of the viscous fluid attached to the outer peripheral surface of the part 12a to be inspected to change, for example, about 1 or 2 seconds.

  When imaging is performed while gas is being blown by the gas blowing device 40, the attachment state of the viscous fluid attached to the inspected portion 12a changes. Specifically, in a state where no gas is blown, the viscous fluid adheres in a convex shape due to surface tension. On the other hand, in the state where the gas is blown, the viscous fluid adhering to the portion where the gas is blown is dispersed to the surroundings, so that the convex viscous fluid changes into a concave shape. Then, the viscous fluid dispersed around it changes into a convex shape.

  Here, the outer tube 11 is filled with grease in order to reduce sliding resistance between the O-ring and the piston rod 12. Therefore, grease may adhere to the piston rod 12. However, since the grease has a higher viscosity than the viscous fluid, the adhesion state does not change even when the gas is blown. Therefore, it is possible to change the adhesion state of only the leaking viscous fluid.

  The two images captured by the camera 30 are color images, but the color images are converted to 8-bit gray scale for easy comparison. The gray scaled image is expressed in gray with different brightness in 256 gradations from white to black. In addition to the method of making a color image grayscale in this way, an image expressed in grayscale may be captured from the beginning using a monochrome camera. Two images may be used as a color image.

  Next, the two grayscale images are compared. That is, the difference between the image captured in a state where no gas is blown and the image captured in a state where gas is blown is taken. Since the images were picked up by the camera 30 fixed while measuring the rotation angle by the encoder 21, the pixels at the same rotation angle in the two images are at the same position, and it is possible to compare the respective pixels. . This process corresponds to the image comparison means.

  Next, the difference between the two images is binarized. If there is a difference in lightness of a predetermined value or more between pixels at the same position, it is assumed that the pixel has changed, and if the lightness difference is smaller than the predetermined value, the pixel has changed. Suppose that there was no. The predetermined value is determined by investigating in advance an experiment or the like a value that changes when the leaked viscous fluid adheres. That is, the minimum brightness difference that changes between the two pixels when viscous fluid is leaking. This is to eliminate a difference in brightness due to an error during imaging.

  When an 8-bit grayscale image is binarized, that is, converted into one bit, it is classified into two types, a pixel that has changed between two images and a pixel that has not changed. That is, it is possible to count the number of pixels that have not changed and the number of pixels that have changed when binarization processing is performed.

  When the number of changed pixels is smaller than the predetermined number, it is determined that the viscous fluid is not leaking, and when it is larger than the predetermined number, it is determined that the viscous fluid is leaking. This is to eliminate a difference due to an error during imaging. This process corresponds to the fluid leakage determination means.

  Here, since the piston rod 12 is made of metal, it is glossy, and the viscous fluid that may leak is transparent. The viscous fluid may have some color, but it is difficult to see because it is in a thin film state when attached.

  However, according to the fluid leakage inspection apparatus 100 that determines fluid leakage by comparing two images, it is possible to accurately detect leakage of viscous fluid regardless of the state of the substrate.

  Further, the piston rod 12 may be polished or plated in the finishing process. For this reason, the imaged image directly shows the state of the substrate, such as a polished trace or a plating process trace, and it is difficult to absolutely determine the leakage of the viscous fluid.

  However, the fluid leakage inspection apparatus 100 determines the leakage of the viscous fluid relatively by comparing the two images. Therefore, it is possible to detect leakage of viscous fluid with high accuracy.

  Moreover, in the fluid leak inspection apparatus 100, the process which an operator determines by automating was eliminated. As a result, it is possible to eliminate variations in determination based on different determination criteria depending on the operator, and to maintain high inspection accuracy.

  According to the above embodiment, the following effects can be obtained.

  The captured image when the gas is blown by the gas blowing device 40 on the inspected portion 12a provided on the piston rod 12 of the shock absorber 10 and the captured image when the gas is not blown are compared by the image comparison means. Then, a relative change between the two images is calculated by gray scale processing or binarization processing, and fluid leakage is determined based on the change. Therefore, it is possible to detect the fluid leakage of the shock absorber 10 with high accuracy.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  INDUSTRIAL APPLICABILITY The fluid leakage inspection apparatus and inspection method according to the present invention can be used for inspection for detecting fluid leakage in a fluid pressure device in which a fluid is sealed, such as a shock absorber.

DESCRIPTION OF SYMBOLS 100 Fluid leak test | inspection apparatus 10 Buffer 11 Outer tube 12 Piston rod 12a Inspected part 20 Electric motor 21 Encoder 30 Imaging means 40 Gas spraying apparatus 50 Controller

Claims (6)

An outer tube in which a fluid chamber is defined by a piston slidably inserted;
A fluid leakage inspection device for a fluid pressure device, comprising a piston rod provided integrally with the piston and capable of moving forward and backward with respect to the outer tube;
Imaging means for capturing an image of a fluid leakage inspection part of the fluid pressure device;
Disturbance imparting means for imparting a disturbance to the inspected part and changing the adhesion state of the leaking fluid;
Image comparison means for comparing images of the inspected part when the disturbance is applied by the disturbance applying means and when the disturbance is not applied;
A fluid leakage inspection apparatus comprising: a fluid leakage determination unit that calculates a change between the two images by the image comparison unit and determines a fluid leakage based on the change.   The fluid leakage inspection apparatus according to claim 1, wherein the disturbance applying unit is a gas spraying apparatus that sprays gas onto the inspected part. Rotating means for rotating the fluid pressure device about its axis,
The fluid leakage inspection device according to claim 1, wherein the imaging unit performs imaging of substantially one circumference of the outer periphery of the fluid pressure device. A rotation angle detection unit capable of detecting a rotation angle of the fluid pressure device rotated by the rotation unit;
The fluid leakage inspection apparatus according to claim 3, wherein the two images are images in which the same part of the inspected part is captured at the same position.   5. The fluid leakage inspection apparatus according to claim 1, wherein the imaging unit captures a gray-scale still image of a fluid leakage inspection portion of the fluid pressure device. 6. And the outer tube the fluid chamber is defined by slidably interpolated by the piston,
A fluid leakage inspection method for a fluid pressure device provided with a piston rod provided integrally with the piston and capable of moving forward and backward with respect to the outer tube;
Taking an image of the fluid leakage inspection part of the fluid pressure device,
Taking an image of the inspected part while applying a disturbance to the inspected part to change the adhesion state of the leaking fluid,
Calculating a change between an image captured without applying the disturbance and an image captured while applying the disturbance;
A fluid leakage inspection method for determining fluid leakage based on a change between two images.