JPH10177009A - Valve seat inspection device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for inspecting defect of valve seat that is directly formed at the cylinder head of an engine. SOLUTION: A guide shaft 20 is inserted into a valve stem guide 18 corresponding to a valve seat 12 to be inspected. A sensor head 22 for carrying an eddy current flaw-detecting sensor 24 and a leakage magnetic flux flaw- detecting sensor 26 is fixed to the guide shaft 20. Two sensors are retained at a position that opposes the inspection target surface of the valve seat 12. After the sensor head 22 is brought into contact with the valve seat 12 by an up/down drive mechanism 60, it is retracted by a specific amount, thus determining the position of the sensors 24 and 26 for the valve seat 12. Then, the sensor head 22 is rotated around the axis of the guide shaft 20 by a motor 42, thus inspecting a defect around the entire periphery of the valve seat 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for inspecting a surface defect of a product, and more particularly to an apparatus and a method for inspecting a valve seat of an engine for a defect.

[0002]

2. Description of the Related Art In a cylinder head of an engine, a portion of a valve seat on which an intake / exhaust valve is seated is exposed to combustion gas and comes into contact with a high-temperature valve, so that high heat resistance is required. In addition, impact resistance is required since the valve receives an impact when the valve is seated. The cylinder head is usually a cast product of an aluminum alloy, but the valve seat is required to have heat resistance and impact resistance as described above, and the aluminum alloy cannot satisfy these requirements. Conventionally, the valve seat is made of a heat-resistant alloy separately from the cylinder head, and is press-fitted into the cylinder head. In this case, the inspection for the defect of the valve seat was performed alone before assembling to the cylinder head.

[0003]

In recent years, a method for directly forming a heat-resistant alloy valve seat on an aluminum alloy cylinder head has been put to practical use. In this method, a powder of a heat-resistant alloy is applied to a portion of a cylinder head that forms a valve seat, and the powder of the heat-resistant alloy is welded by irradiating a laser beam to form a valve seat. In this case, since the valve seat is formed directly on the cylinder head, it is not possible to perform a single item inspection as in the related art. And the cylinder head is much larger than the conventional single valve seat, and when measuring by moving the cylinder head with respect to the sensor, the distance between the sensor and the valve seat cannot be sufficiently guaranteed. The detection accuracy cannot be improved. Therefore, it is necessary to fix the cylinder head and move the sensor to detect a defect. However, there has not been a technique for accurately maintaining the distance between the sensor and the inspection target surface of the valve seat.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an apparatus and a method for inspecting a valve seat formed directly on a cylinder head for defects.

[0005]

In order to achieve the above object, an apparatus according to the present invention is a valve seat inspection apparatus for inspecting a valve seat formed on an engine cylinder head for defects. A guide shaft that is inserted into the inner diameter of the valve stem guide corresponding to the valve seat and is positioned in the radial direction by the valve stem guide; a sensor that detects a defect in the valve seat; and the sensor facing the valve seat. It has a sensor head carried at a position, and a rotation drive mechanism for rotating the sensor head around the guide shaft.

A method of inspecting a valve seat for defects using this apparatus is to rotate a sensor head around the guide shaft and to move a sensor carried by the sensor head in a circumferential direction along the surface of the valve seat. Move. At this time, the defect is detected in a predetermined range in the circumferential direction of the valve seat, preferably in the entire circumference.

In the cylinder head, the inner diameter of the valve stem guide and the valve seat are formed with predetermined dimensional accuracy. The intake / exhaust valve reciprocates along the valve stem guide, and when the valve is closed, the head of the valve and the valve seat need to be in close contact. Therefore, the coaxiality and orthogonality between the valve stem guide inner diameter and the valve seat are processed with high accuracy. Therefore, by inspecting the valve seat based on the valve stem guide, the distance between the valve seat and the sensor can be maintained constant, and the inspection accuracy is guaranteed.

Further, the valve seat inspection apparatus may further include an advance / retreat drive mechanism for driving the sensor head to advance / retreat in the axial direction of the guide shaft.

In the method of inspecting a valve seat using the device having the advance / retreat drive mechanism, the sensor is brought into contact with the surface of the valve seat, and then the advance / retreat drive is performed so that the distance between the sensor and the valve seat becomes a predetermined value. The mechanism retracts the sensor. Thus, in each measurement, the distance between the sensor and the valve seat can be kept constant.

Further, in the above-described apparatus, the sensor may include at least one of an eddy current flaw detection sensor and a leakage magnetic flux flaw detection sensor. The eddy current flaw detection sensor is suitable for detecting a defect such as a dent having a substantially circular contour, and the leakage magnetic flux flaw detection sensor is suitable for detecting a linear defect such as a scratch. By providing both, it is possible to reliably detect defects having various shapes.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a valve seat inspection apparatus 10 of the present embodiment and a cylinder head 14 on which a valve seat 12 to be inspected is formed. The cylinder head 14 is provided with an intake port and an exhaust port for each cylinder. In FIG. 1, only one of the intake and the exhaust is shown, and when there is no need to distinguish in the following description, it is simply referred to as a port 16. A valve seat 1 is provided at the outlet of the port, that is, at the edge of the portion facing the combustion chamber.
2 are formed. The valve seat 12 is formed by welding a powder of a heat-resistant alloy on a cylinder head 14 made of an aluminum alloy, irradiating the powder with a laser beam, and further forming it into a predetermined shape by machining. A valve stem guide 18 is press-fitted into a port portion of the cylinder head 14. The valve stem guide 18 has a circular tube shape, and a valve stem is inserted into the inner diameter thereof to guide the reciprocating operation of the valve. The head portion of the valve is in close contact with the valve seat 12 when the valve is closed. In order to ensure this adhesion, the relative dimensional accuracy between the inner diameter of the valve stem guide 18 and the surface of the valve seat 12 is secured to a predetermined value. For example, the central axes of the valve stem guide 18 and the valve seat 12 are formed so as to coincide within a predetermined dimensional accuracy, that is, are formed with a predetermined coaxiality. The central axis of the valve stem guide 18 and the plane on which the valve seat 12 is formed are formed so as to be orthogonal to each other within a predetermined dimensional accuracy, that is, at a predetermined orthogonality.

The inspection device 10 includes a valve stem guide 18
And a sensor head 22 that moves integrally with the guide shaft 20. The guide shaft 20 is
When inserted into the valve stem guide 18, it has a diameter such that it can move in the axial direction but cannot move in the direction (radial direction) perpendicular to the axis. That is,
When the guide shaft 20 is inserted, there is substantially no gap between the guide shaft 20 and the inner diameter of the valve stem guide 18. The apex angle of the sensor head 22 is 90 ° at the tip (lower side in the figure).
A frusto-conical portion 22a, which is a part of the conical portion, carries an eddy current flaw detection sensor 24 and a leakage magnetic flux flaw detection sensor 26 on the side surface of the frusto-conical portion 22a. Thereby, two sensors 2
Reference numerals 4 and 26 are arranged to face a surface of the valve seat 12 which actually contacts the valve, that is, a so-called 90 ° surface. The relative arrangement of the two sensors 24, 26 is provided at 180 ° in the circumferential direction, that is, on the opposite side. Also,
A magnetization yoke 28 is arranged adjacent to the magnetic flux leakage sensor 26.

The guide shaft 20 and the sensor head 22 are
A plane orthogonal to the guide shaft 20 (hereinafter referred to as an XY plane)
XY plane floating mechanism 3 that allows movement only inside
0 supported. The XY plane floating mechanism 30 is fixed to a sleeve 34 provided at the distal end of the stroke head leakage magnetic flux detection sensor. Sleeve 3
4 is supported by a bearing 38 coaxially with the inner cylinder 36 and rotatably. A sleeve 34 is provided on the outer circumference of the inner cylinder 36.
Gear 40 is rotatably supported adjacent to the sleeve 3
The gear 4 and the gear 40 are fastened so as to rotate integrally. The gear 40 meshes with a drive gear 44 fixed to a drive shaft of a motor 42, and the rotation of the motor 42 drives the gear 40, the sleeve 34, the sensor head 22, the guide shaft 20, and the like to rotate.

On the outer periphery of the inner cylinder 36, the aforementioned sleeve 34
The outer cylinder 46 is fitted in addition to the gear and the gear 40,
And the outer cylinder 46 are relatively movable in the axial direction. A lock-up mechanism 48 is provided at an end of the outer cylinder 46.
0 and a lock-up piston 52, and the lock-up piston 52 is connected to the inner cylinder 36 by a piston rod 54. Therefore, the lock-up cylinder 50
Moves integrally with the outer cylinder 46, and the lock-up piston 52 moves integrally with the inner cylinder 36. The lock-up mechanism 48 includes a mechanism that selectively locks the lock-up cylinder 50 and the lock-up piston 52, and is integrated when locked. Thereby, at the time of locking, the inner cylinder 36 and the outer cylinder 46 move integrally.

The outer cylinder 46 is fixed to a plate 56, and the motor 42 is also fixed on the plate 56. The plate 56 is driven up and down along a guide 58 by a vertical drive mechanism 60. Therefore, the sensor head 22 moves up and down, that is, moves back and forth with respect to the cylinder head 14 by this up and down operation.

The power supply to the magnetized yoke 28, the eddy current flaw detection sensor 24, and the leakage magnetic flux flaw detection sensor 26, and the reception of signals from these sensors 24 and 26 are performed by the inner cylinder 36.
The rotation is performed via a slip ring 62 arranged at the inner diameter of the sensor head 22 so that the torsion caused by the rotation of the sensor head 22 is absorbed. The detection signals from the sensors 24 and 26 are sent to a control unit (not shown), and the control unit calculates the presence or absence of a defect and the size based on the signal waveform.

Next, the operation of the inspection apparatus 10 for detecting a defect in the valve seat 12 will be described. FIG. 2 shows a control timing chart of each mechanism, sensor, and the like of the present apparatus. The inspection device 10 is a valve seat 1 to be inspected.
2, the vertical drive mechanism 60 operates to lower the sensor head 22 by a predetermined amount (10).
0). This lowering amount is based on the home position of the sensor head 22 and the dimensions of the cylinder head 14 on which the valve seat 12 to be inspected is provided, and has a sufficient margin so that the tip of the sensor head 22 does not contact the valve seat 12. The value is predetermined. The guide shaft 20 is gradually inserted into the valve stem guide 18 during the downward movement. At this time, the XY plane floating mechanism 30
If the misalignment between the guide shaft 20 and the valve stem guide 18 is slight, it is absorbed. When this descent ends,
Subsequently, the lowering operation is performed at a low speed (102). When the descent at this low speed is started, electric power is supplied to the eddy current flaw detection sensor 24, the leakage magnetic flux flaw detection sensor 26, and the magnetized yoke 28, so that it is possible to detect that these sensors have contacted the valve seat 12. (104,106).

At the moment when the eddy current flaw detection sensor 24 and the leakage magnetic flux flaw detection sensor 26 come into contact with the valve seat 12, the sensor outputs have waveforms 108 and 110. When this waveform is output, contact confirmation signals 112 and 114 are transmitted.
The low-speed lowering drive control of the vertical drive mechanism 60 is continued for a predetermined time or until the lowering is performed by a predetermined amount. After the contact of the sensor head 22, the sensor head 22 does not further descend, but since the lock-up mechanism 48 is still released, the inner cylinder 36 and the outer cylinder 46 move relatively to buffer the vertical movement. Play a role. When the slow descent ends,
The power supply to the two sensors 24 and 26 is stopped, and the transmission of the contact confirmation signals 112 and 114 is also stopped. And
At the same time, the lock-up mechanism 48 is locked-up controlled (116), so that the inner cylinder 36 and the outer cylinder 46 cannot move relative to each other.

Next, the sensor head 22 is driven up by a predetermined amount by the vertical drive mechanism 60 (118). The predetermined amount is determined so that the inspection target surface, that is, the 90 ° surface of the valve seat 12 and the gap between the sensors 24 and 26 have an appropriate value when the eddy current detection sensor 24 and the leakage magnetic flux detection sensor 26 detect a surface defect. Have been. This rise 118
Is completed, the sensor head 22 is rotationally driven by the motor 42 (120). This rotation is performed by the sensor head 2
2 lasts slightly longer than one rotation, and the sensor head 22
Power is supplied to the eddy current flaw detection sensor 24, the leakage magnetic flux flaw detection sensor 26, and the magnetized yoke 28 during just one rotation (122, 124), and defect detection, that is, flaw detection operation is performed. Then, based on the output waveforms (126, 128) from the sensors 24, 26, the presence / absence of a defect in the valve seat 12 and its size are calculated. Here, the reason why the sensor head 22 is driven to rotate more than one rotation is that the angular velocity is often unstable at the beginning of rotation, and the detection accuracy in this part may be reduced. That is, flaw detection is not performed at the beginning of rotation, and flaw detection is started after rotation by a predetermined angle.

After the flaw detection operation is completed, the sensor head 22 is controlled to be lowered by the vertical drive mechanism 60 (130). This lowering amount is equal to the raising amount in the previous drive control (118), whereby the sensor head 22 comes into contact with the valve seat surface again. Then, the lock-up mechanism 48 is released (116), and the entire inspection apparatus 10 is driven upward by the vertical drive mechanism 60 (132), and the defect detection operation ends.

FIG. 3 shows a schematic configuration of a valve seat inspection device 66 formed on a cylinder head 64 of an in-line four-cylinder engine. The inspection device 66 has the same device as the inspection device 10 shown in FIG. 1 corresponding to each of the four cylinders, and the same components as those described in FIG. 1 are denoted by the same reference numerals. . The inspection device 66 has a sensor head 22, a stroke cylinder 32, and a lock-up mechanism 48 for each cylinder, and has the same configuration as the inspection device 10 described above. That is, the sensor head 22
Is provided with an eddy current flaw detection sensor and a leakage magnetic flux flaw detection sensor, and is also provided with a guide shaft 20 inserted into the valve stem guide. The stroke heads 32 provided for the respective cylinders are arranged on one plate 68, and this plate 68
Driven in the vertical direction. Therefore, the four sensor heads 22 are driven in the vertical direction in synchronization.

Further, when there is a valve seat having the same diameter and parallel axes to each other as in an engine having a pent roof type combustion chamber with four valves per cylinder, one valve seat is inspected in one cylinder. Thereafter, each sensor head is moved in parallel, and another valve seat is inspected. For this purpose, the inspection device 66 includes a left-right driving mechanism 72 that moves the sensor head 22 in the left-right direction.
have. Since the diameter of the valve seat of the intake valve and the diameter of the valve seat of the exhaust valve are different and their axes are not parallel, the inspection device 10 and the inspection device 66 are separately provided corresponding to each of the intake side and the exhaust side. Although provided, the only difference is the diameter of the truncated cone portion 22a of the sensor head 22.

In the above inspection devices 10 and 66, the positional relationship with the valve seat 12 to be inspected is
By using the valve stem guide 18 having a predetermined dimensional accuracy as a reference, the distance between the sensors 24 and 26 and the valve seat 12 can always be kept constant, and the inspection accuracy can be improved.

The sensor head 22 is connected to the valve seat 1.
After the contact with the valve seat 2, the sensor 24 is retracted by a predetermined distance, so that the positions of the sensors 24 and 26 with respect to the valve seat 12 at the time of inspection can be accurately determined. In addition, the sensor head 2
The contact of the second valve seat 12 with the valve seat 12 is detected by also using a sensor for inspection, so that it is not necessary to add a new configuration, and the apparatus can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a valve seat inspection device according to an embodiment of the present invention.

FIG. 2 is a timing chart of an inspection operation of the inspection apparatus.

FIG. 3 is a schematic configuration diagram of an inspection device corresponding to a cylinder head of an in-line four-cylinder engine.

[Explanation of symbols]

10,66 Inspection device, 12 Valve seat, 14,6
4 cylinder head, 18 valve stem guide, 20
Guide shaft, 22 sensor head, 24 eddy current flaw detection sensor, 26 leakage magnetic flux flaw detection sensor, 28 magnetization yoke, 4
8 Lock-up mechanism, 60 vertical drive mechanism.

Claims (5)

[Claims] A valve seat inspection device for inspecting a valve seat formed on a cylinder head of an engine for a defect, wherein the device is inserted into an inner diameter of a valve stem guide corresponding to a valve seat to be inspected. A guide shaft positioned in the radial direction, a sensor for detecting a defect in the valve seat, a sensor head for carrying the sensor at a position facing the valve seat, and rotating the sensor head about the guide shaft. A valve seat inspection apparatus, comprising: a rotation drive mechanism, wherein the sensor head is rotated by the rotation drive mechanism to detect a defect. 2. The valve seat inspection apparatus according to claim 1, further comprising: an advance / retreat drive mechanism for driving the sensor head to advance / retreat in the axial direction of the guide shaft, wherein the advance / retreat drive mechanism is configured such that the sensor is mounted on the valve seat. A valve seat inspection device that retracts the sensor head by a predetermined distance from a contact position and detects a defect at the retracted position. 3. The valve seat inspection device according to claim 1, wherein the sensor has at least one of an eddy current detection sensor and a leakage magnetic flux detection sensor.
Valve seat inspection device. 4. A valve seat inspection method for inspecting a valve seat formed on a cylinder head of an engine for defects in a valve seat guide corresponding to a valve seat to be inspected. A step of inserting a guide shaft to be performed, and a step of rotating a sensor for detecting a defect in the valve seat about the guide shaft as an axis to detect the defect along a circumferential direction of the valve seat. 5. The valve seat inspection method according to claim 4, wherein the sensor is once brought into contact with the valve seat before the step of detecting a defect, and then the sensor is separated from the valve seat by a predetermined distance. A method for inspecting a valve seat, comprising the step of, in this step, contacting the sensor with the valve seat based on a detection output of the sensor.