Measurement fixture

Abstract

The present invention provides a measuring jig capable of efficiently performing quality control of multi-stage enlarged diameter holes when a valve seat forms a multi-stage enlarged diameter hole. The measuring jig measures the hole shape of a multi-stage enlarged diameter hole formed coaxially with the guide hole at the opening end of the valve hole formed coaxially with the guide hole. The measuring jig comprises: a shaft portion, which is inserted into the guide hole; a reference measuring piece, which is integrally provided with the shaft portion and is positioned at a first step portion that serves as a reference for measurement; a second movable measuring piece, which is configured to be movable in the axial direction of the shaft portion relative to the outer peripheral surface of the reference measuring piece and abuts against the second step portion; and a second measuring device, which measures the amount of movement of the second movable measuring piece relative to the reference measuring piece. The second measuring device measures the amount of movement of the second movable measuring piece based on the position where the reference measuring piece abuts against the first step portion.

Description

Technical Field

[0001] The present invention relates to a measuring jig for measuring the hole shape near the opening end of a valve hole. Background Art

[0002] In recent years, with the development of automobiles centered on high output and low fuel consumption, achieving optimal combustion conditions in the engine's combustion chamber is crucial for improving combustion efficiency. Therefore, maintaining a certain level of component processing accuracy in the production technology of valve seats and valves incorporated into the engine's cylinder head is crucial for manufacturing high-output, low-fuel engines.

[0003] The following structures exist as structures for inspecting the machining accuracy of valve holes. Patent Document 1 describes a device that measures the height of a portion of a shield formed around the opening end of the valve hole, with a measuring ring that moves relative to the positioning portion. The height of the shield is measured by bringing the measuring ring into contact with the shield. Furthermore, Patent Document 2 describes a device that measures the inner diameter of the shield by bringing the measuring ring into contact with the positioning portion. The inner diameter of the shield is measured by bringing the measuring ring into contact with the inner wall of the shield while the measuring ring is brought into contact with the positioning portion.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-062811

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-055888 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, the machining accuracy of the contact surface between the valve seat and the valve affects the sealing of the combustion chamber and the accuracy of the valvetrain's operation, requiring higher machining accuracy than that of the shroud. Furthermore, in recent years, the valve seat's contact surface has become more complex with a multi-stage expanded hole, necessitating even higher machining accuracy. When inspecting the machining accuracy of such a multi-stage expanded hole, the aforementioned method cannot precisely measure the hole shape.

[0010] Therefore, when measuring the hole shape of multi-stage expanded holes, a profile measuring machine, a general-purpose precision measuring machine, is used. However, to perform inspections using the profile measuring machine, the cylinder head must be transported off-line from the production line, or the valve seat must be removed from the valve hole, transported to a clean room, etc., and then transported to the profile measuring machine. This requires significant labor and time, making efficient quality control difficult.

[0011] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a measuring jig capable of efficiently performing quality control of a multi-step diameter-expanded hole when a multi-step diameter-expanded hole is formed in a valve seat.

[0012] Technical solutions to problems

[0013] In order to achieve this purpose, the invention involved in technical solution 1 is a measuring fixture (1) that measures the hole shape of a multi-stage enlarged hole, wherein the multi-stage enlarged hole is formed coaxially with the reference shaft hole (guide hole 11a) at an opening end (12a) of a hole portion (valve hole 12) formed coaxially with the reference shaft hole, and forms a plurality of step portions and expands the diameter in stages, and the measuring fixture comprises: a shaft portion (31) that is inserted into the reference shaft hole; a reference measuring piece (32) that is integrally provided with the shaft portion and is positioned on a reference table that serves as a reference for measurement among the plurality of step portions step portion (first step portion 21); a movable measuring piece (second movable measuring piece 50), which is configured to be movable in the axial direction of the shaft portion relative to the outer peripheral surface of the reference measuring piece and abut against a step portion (second step portion 22) different from the reference step portion among the multiple step portions; and a movement amount detection portion (second measuring device 75), which measures the movement amount of the movable measuring piece relative to the reference measuring piece, and the movement amount detection portion measures the movement amount of the movable measuring piece based on the position where the reference measuring piece abuts against the reference step portion.

[0014] In this way, when measuring the shape of a multi-step expanded hole, with the reference measuring piece positioned on the reference step, the movement of the movable measuring piece is measured using the position at which the reference measuring piece abuts the reference step as a reference. If the axial distance between the reference step and the shaft portion of a step different from the reference step can be determined, then by knowing the inner diameter of the reference step in advance, the inner diameter of the step different from the reference step and the surface width between the reference step and the step different from the reference step can also be calculated. Thus, multiple lengths in the hole shape can be determined. Furthermore, these measurements can be performed by directly inserting a measuring fixture into the multi-step expanded hole, eliminating the need for a separate contour measuring machine, enabling efficient quality control on the production line. Consequently, efficient quality control of multi-step expanded holes is possible.

[0015] The invention involved in Technical Solution 2 is characterized in that, in the measuring fixture described in Technical Solution 1, the measuring fixture further comprises: a reference movable measuring piece (a first movable measuring piece 40), which is configured to be movable in the axial direction of the shaft portion relative to the outer peripheral surface of the reference measuring piece and abut against the reference step portion among the multiple step portions; and a reference movement amount detection portion (a first measuring device 71), which measures the movement amount of the reference movable measuring piece relative to the reference measuring piece, and the reference movement amount detection portion measures the movement amount of the reference movable measuring piece and the movable measuring piece based on the position where the reference measuring piece abuts against the reference step portion.

[0016] By using the reference movable measuring piece in addition to the reference measuring piece as the measuring piece that contacts the reference step portion, the inner diameter of the reference step portion can be measured more accurately. Consequently, the inner diameter of a step portion different from the reference step portion and the surface width between the reference step portion and the step portion different from the reference step portion can be measured more accurately.

[0017] The invention involved in Technical Solution 3 is characterized in that, in the measuring fixture described in Technical Solution 2, the reference movable measuring piece and the movable measuring piece are slidably arranged in two grooves (first groove 36 and second groove 37) formed on the outer peripheral surface of the reference measuring piece, and are retained relative to the reference measuring piece by an elastic component (O-ring 60), and retaining grooves (38, 48, 58) for retaining the elastic component are respectively formed on the outer peripheral surface of the reference measuring piece, the outer peripheral surface of the reference movable measuring piece, and the outer peripheral surface of the movable measuring piece.

[0018] In this way, if the reference measuring piece, the reference movable measuring piece, and the movable measuring piece are held by an elastic member, when the reference movable measuring piece and the movable measuring piece come into contact with the step, the elastic deformation of the elastic member causes a restoring force to act. This restoring force becomes a measurement load, enabling precise measurement.

[0019] The invention involved in Technical Solution 4 is characterized in that, in the measuring fixture described in any one of Technical Solutions 1 to 3, the multi-stage expanded hole is formed in a valve seat (20) arranged in the valve hole (12) of the cylinder head (10) of the engine, and the surface (second surface 26) between the reference step portion and the step portion different from the reference step portion constitutes the abutment surface of the valve seat.

[0020] In this way, the multi-step expanded diameter hole is formed in the valve seat arranged in the valve hole of the engine cylinder head, and the surface between the reference step portion and the step portion different from the reference step portion constitutes the valve seat contact surface. This allows the surface width of the valve seat contact surface to be precisely measured.

[0021] The invention involved in Technical Solution 5 is characterized in that, in any one of Technical Solutions 1 to Technical Solution 4, the multiple step portions are formed by multiple continuous inclined surfaces whose inclination angle relative to the shaft portion gradually increases as approaching the opening end, the reference measuring piece, the reference movable measuring piece and the movable measuring piece respectively have inclined surfaces (33, 43, 53) abutting the step portions, and the inclined surfaces of the reference measuring piece, the reference movable measuring piece and the movable measuring piece respectively form an inclination angle relative to the shaft portion in a manner that is smaller than the inclination angle of the inclined surface on the side close to the opening end among the inclined surfaces adjacent to the step portions abutting each measuring piece and is larger than the inclination angle of the inclined surface on the side away from the opening end.

[0022] In this way, the angles of the inclined surfaces formed on the reference measuring element, the reference movable measuring element, and the movable measuring element are each smaller than the angle of the inclined surface on the side closer to the opening end and larger than the angle of the inclined surface on the side farther from the opening end. This allows the inclined surfaces of each measuring element to directly contact each step, enabling precise measurement of the shape of a multi-stage expanded hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This figure shows the overall structure of the measuring jig and the positional relationship of the measuring jig with respect to the valve hole.

[0024] Figure 2 It means from Figure 1 A diagram showing the overall structure of the measurement jig viewed from the A direction.

[0025] Figure 3 1 and 2 are diagrams showing the configurations of a first movable measuring element and a second movable measuring element. (A) is a configuration diagram of the first movable measuring element, and (B) is a configuration diagram of the second movable measuring element.

[0026] Figure 4 This is a diagram showing a state in which the first movable measuring element and the second movable measuring element are held by the reference measuring element.

[0027] Figure 5 The figures show the state of the O-ring when the valve seat and the first movable gauge are in contact with each other. (A) shows the state before the contact, and (B) shows the state during the contact.

[0028] Figure 6 It is a cross-sectional view showing the detailed structure of the valve seat.

[0029] Figure 7 The figures show the inclination angle of the valve seat and the inclination angle of the measuring piece. (A) shows the taper angle of the reference measuring piece, (B) shows the inclination angle of the first movable measuring piece, and (C) shows the inclination angle of the second movable measuring piece.

[0030] Figure 8 It is a schematic diagram showing the state of the measurement jig during measurement. DETAILED DESCRIPTION

[0031] The following describes in detail a measuring jig 1 according to a first embodiment of the present invention with reference to the accompanying drawings. In order to facilitate understanding of the structure of the valve hole 12 and valve seat 20 of the cylinder head 10, the following diagrams are presented with the openings facing upward. References to "up" and "down" in the following description refer to the "up" and "down" directions in the accompanying drawings, unless otherwise specified. Furthermore, the axial direction refers to a direction parallel to the axis 11X of the guide hole 11a (the axial direction of the shaft portion 31).

[0032] use Figure 1 The structure of the measuring jig 1 and its relationship with the vicinity of the valve hole 12 of the cylinder head 10 will be described. Figure 1 The diagram shows the overall structure of the measuring jig 1 and its positional relationship with respect to the valve hole 12. The measuring jig 1 measures the hole shape of the valve seat 20 disposed at the opening end 12a of the valve hole 12 formed in the cylinder head 10 of the engine.

[0033] First, the structure of the cylinder head 10 will be described. A valve hole 12 for intake or exhaust is formed in the cylinder head 10. A guide hole 11a of the valve guide 11 is formed on the side of the valve hole 12 opposite to the open end 12a (below in the figure). The guide hole 11a is a hole into which the shaft of a valve (not shown) is inserted when the cylinder head 10 is in use. The valve moves axially along the axis 11X of the guide hole 11a, thereby performing intake and exhaust from the cylinder head 10 relative to the combustion chamber (not shown). The valve hole 12 is formed coaxially with the axis 11X of the guide hole 11a. A valve seat 20 is arranged at the open end 12a of the valve hole 12. A multi-stage enlarged hole is formed in the valve seat 20, which has a plurality of steps and is enlarged in stages. When viewed from the side of the open end 12a, the plurality of steps are formed in a circular shape. A detailed description of the multi-stage enlarged hole will be described later.

[0034] use Figure 1 and Figure 2 The structure of the measurement jig 1 will be described. Figure 2 It means from Figure 1 The entire structure of the measuring jig is viewed from the direction A. The measuring jig 1 is configured such that a first movable measuring element 40 and a second movable measuring element 50 are held on a main body 30 by an O-ring 60 , and a measuring device 70 measures the amount of movement of the first movable measuring element 40 and the second movable measuring element 50 .

[0035] The main body 30 includes a shaft 31 inserted into the guide hole 11 a , a reference measuring piece 32 for positioning relative to the valve seat 20 , and a measuring instrument holding portion 35 for fixing and holding the measuring instrument 70 . These components are integrally provided.

[0036] The shaft portion 31 has a shaft diameter that fits into the guide hole 11a of the valve guide 11. Thus, the shaft portion 31 slides along the guide hole 11a, and the main body portion 30 can be moved in the axial direction along the axis 11X of the guide hole 11a.

[0037] The cross section of the reference measuring member 32 on a plane perpendicular to the axis 11X is formed into a substantially circular shape centered on the axis 11X (see Figure 4 ), and the entire structure is cylindrical. A conical tapered surface 33 is formed at the end (lower end) on the shaft portion 31 side of the reference measuring member 32, which continuously expands in diameter as it moves away from the shaft portion 31. A first groove portion 36 and a second groove portion 37 are formed on the outer peripheral surface (side surface in the figure) of the reference measuring member 32, extending in the axial direction. A first movable measuring member 40 is arranged in the first groove portion 36, and a second movable measuring member 50 is arranged in the second groove portion 37. In addition, a retaining groove 38 is formed along the circumferential direction on the outer peripheral surface of the reference measuring member 32. An O-ring 60 is accommodated in the retaining groove 38 along the circumferential direction. Thus, the retaining groove 38 retains the O-ring 60.

[0038] The measuring device holding part 35 has a cylindrical appearance and fixes and holds the measuring device 70. Specifically, the bases 72 and 76 of the measuring device 70 are inserted into the through hole 35h that passes through the measuring device holding part 35 in the vertical direction. Figure 2 ) Insert a bolt (not shown) into the holding hole 35b, and use the tip of the bolt to press and fix each base 72, 76. In this way, the measuring device holding portion 35 fixes and holds the measuring device 70.

[0039] The measuring instrument 70 is a standard micrometer. The measuring instrument 70 of this embodiment includes a first measuring instrument 71 and a second measuring instrument 75. The first measuring instrument 71 includes a base 72, a measuring rod 73 having a tip 73a, and a display unit 74. The measuring rod 73 is configured to be extendable and retractable in the axial direction relative to the base 72, so that the tip 73a of the measuring rod 73 abuts the first movable measuring member 40. This configuration allows the amount of movement measured by the movement of the measuring rod 73 to be displayed on the display unit 74. The display unit 74 includes a needle 74a that rotates about a central axis in accordance with the axial movement of the measuring rod 73, and a scale 74b (not shown). The numerical value indicated by the scale indicated by the needle 74a is measured as the amount of movement of the first movable measuring member 40.

[0040] The second measuring instrument 75 includes a base 76, a measuring rod 77 having a distal end 77a, and a display unit 78. The structure of the second measuring instrument 75 is identical to that of the first measuring instrument 71, and therefore a detailed description thereof will be omitted. The structure of the measuring instrument 70 is not limited to this; as long as the axial movement of the first movable measuring element 40 and the second movable measuring element 50 can be measured, a dial indicator is not required.

[0041] use Figure 3 The structure of the movable measuring element will be described. Figure 3 1 is a diagram showing the structure of the first movable measuring element 40 and the second movable measuring element 50. Figure 3 (A) is a structural diagram of the first movable measuring member 40, Figure 3 (B) is a structural diagram of the second movable measuring element 50.

[0042] The first movable measuring element 40 has a flat surface 41 formed on the surface that contacts the distal end 73a of the measuring rod 73 of the first measuring device 71, and an inclined surface 43 formed on the surface that contacts the multi-step expanded diameter hole of the valve seat 20. Furthermore, a sliding surface 45 that is configured to face and slide freely relative to the first groove 36 of the reference measuring element 32 is formed parallel to the axial direction. A retaining groove 48 for retaining the O-ring 60 is formed on the outer diameter surface of the reference measuring element 32.

[0043] The second movable measuring element 50 has a flat surface 51 formed on the surface that contacts the distal end 77a of the measuring rod 77 of the second measuring device 75, and an inclined surface 53 formed on the surface that contacts the multi-stepped diameter hole of the valve seat 20. Furthermore, a sliding surface 55, which is arranged to face and slide freely relative to the second groove 37 of the reference measuring element 32, is formed parallel to the axial direction. A retaining groove 58 for retaining an O-ring 60 is formed on the outer diameter surface of the reference measuring element 32.

[0044] use Figure 4 The structure in which the movable measuring element is held by the reference measuring element will be described. Figure 4 1 is a diagram showing a state in which the first movable measuring element 40 and the second movable measuring element 50 are held by the reference measuring element 32. Figure 4When viewed from the direction (axially upward), the first movable measuring element 40 is positioned so as to fit into the first groove 36 of the reference measuring element 32, and the portion of the first movable measuring element 40 where the retaining groove 48 is formed protrudes from the outer periphery of the reference measuring element 32. Similarly, the second movable measuring element 50 is positioned so as to fit into the second groove 37 of the reference measuring element 32, and the portion of the second movable measuring element 50 where the retaining groove 58 is formed protrudes from the outer periphery of the reference measuring element 32. In this state, the O-ring 60, which is housed and retained in the retaining groove 38 of the reference measuring element 32, is positioned across the retaining groove 48 of the first movable measuring element 40 and the retaining groove 58 of the second movable measuring element 50. Thus, the first movable measuring element 40 and the second movable measuring element 50 are retained by the reference measuring element 32.

[0045] In this embodiment, the first movable measuring element 40 and the second movable measuring element 50 are held by O-rings 60, but the present invention is not limited thereto. However, since the holding member needs to be elastically deformable, it is formed of at least some elastic member.

[0046] use Figure 5 The state of the O-ring 60 during measurement is shown. Figure 5 1 is a diagram showing a state of the O-ring 60 when the valve seat 20 and the first movable gauge 40 are in contact with each other. Figure 5 (A) is a diagram showing the state before contact. Figure 5 (B) is a diagram showing the state when in contact.

[0047] like Figure 5 As shown in (A), before the valve seat 20 contacts the first movable gauge 40, the load from the valve seat 20 is not applied to the O-ring 60 held in the retaining groove 38 of the reference gauge 32 and the retaining groove 48 of the first movable gauge 40. Figure 5 As shown in (B), when the valve seat 20 abuts the first movable gauge 40, the valve seat 20 pushes up the first movable gauge 40. Consequently, the O-ring 60 is elastically deformed by being clamped between the retaining groove 38 of the reference gauge 32 and the retaining groove 48 of the first movable gauge 40. This elastic deformation of the O-ring 60 generates a restoring force. This restoring force serves as the measurement load. The state of the O-ring 60 when the valve seat 20 abuts the second movable gauge 50 is the same as when it abuts the first movable gauge 40, so its description will be omitted.

[0048] use Figure 6 , the hole shape of the multi-stage expanded hole formed in the valve seat 20 as the measurement object will be described in detail. Figure 6This is a cross-sectional view showing the detailed structure of the valve seat 20. The multi-step expanded diameter hole formed in the valve seat 20 is formed by a plurality of continuous inclined surfaces whose inclination angle relative to the axis 11X of the guide hole 11a gradually increases as the angle approaches the opening end 12a from the side closest to the shaft portion 31 of the valve hole 12. The portion where the inclination angle changes is a step portion.

[0049] The multiple steps formed on the valve seat 20 include a first step 21, a second step 22, and a third step 23, arranged in this order as they progress downward from the open end 20a of the valve seat 20 on the side of the open end 12a of the valve hole 12. These steps are all circular when viewed from the axial direction. The inner diameter of the first step 21 is inner diameter D1, and the inner diameter of the second step 22 is inner diameter D2.

[0050] Furthermore, the multiple steps of the valve seat 20 form inclined surfaces at a predetermined angle relative to the axis 11X of the guide hole 11a. Specifically, as the valve seat 20's open end 20a, which is located on the side of the open end 12a of the valve hole 12, progresses downward in the figure, a first surface 25, a second surface 26, and a third surface 27 are formed, adjacent to each other in that order. The first surface 25 is formed between the open end 20a and the first step 21, the second surface 26 is formed between the first step 21 and the second step 22, and the third surface 27 is formed between the second step 22 and the third step 23.

[0051] Here, the second surface 26 forms the contact surface of the valve seat 20. The contact surface is the surface against which the valve contacts, so it is desirable to have detailed dimensions. Specifically, the contact surface width W is the width between the inner diameters of the first step 21 and the second step 22 of the contact surface.

[0052] The multi-step expanded diameter hole is a series of inclined surfaces whose inclination angle relative to the axis 11X of the guide hole 11a gradually increases as the angle approaches the open end 12a from the side closest to the shaft portion 31 of the valve hole 12. Therefore, if the inclination angle of the first surface 25 is θ1, the inclination angle of the second surface 26 is θ2, and the inclination angle of the third surface 27 is θ3, the relationship θ1>θ2>θ3 holds.

[0053] Next, the relationship between the inclination angle of the valve seat and the inclination angle of the measuring tool will be described. Figure 7 This is a diagram showing the relationship between the inclination angle of the valve seat and the inclination angle of the measuring piece. Figure 7 (A) is a diagram showing the taper angle (inclination angle) of the reference measuring member 32. Figure 7 (B) is a diagram showing the inclination angle of the first movable measuring member 40. Figure 7 (C) is a diagram showing the inclination angle of the second movable measuring element 50 .

[0054] like Figure 7 As shown in (A), the tapered surface 33 of the reference measuring member 32 has a taper angle θ33 relative to the axis 11X of the guide hole 11a. Specifically, the taper angle θ33 is smaller than the inclination angle θ1 of the first surface 25, on the side closer to the opening end 12a, of the inclined surfaces (first surface 25 and second surface 26) adjacent to the first step 21 with which the reference measuring member 32 abuts. Furthermore, the taper angle θ33 is larger than the inclination angle θ2 of the second surface 26, on the side farther from the opening end 12a. With this structure, the tapered surface 33 of the reference measuring member 32 abuts the first step 21.

[0055] like Figure 7 As shown in FIG. 1B , the inclined surface 43 of the first movable measuring element 40 has an inclination angle θ43 relative to the axis 11X of the guide hole 11a. Specifically, the inclination angle θ43 is smaller than the inclination angle θ1 of the first surface 25, on the side closer to the opening end 12a, of the inclined surfaces (the first surface 25 and the second surface 26) adjacent to the first step 21 with which the first movable measuring element 40 abuts. Furthermore, the inclination angle θ43 is larger than the inclination angle θ2 of the second surface 26, on the side farther from the opening end 12a. With this structure, the inclined surface 43 of the first movable measuring element 40 abuts the first step 21.

[0056] like Figure 7 As shown in (C), the inclined surface 53 of the second movable measuring element 50 has an inclination angle θ53 relative to the axis 11X of the guide hole 11a. Specifically, the inclination angle θ53 is smaller than the inclination angle θ2 of the second surface 26 on the side closer to the opening end 12a, among the inclined surfaces (the second surface 26 and the third surface 27) adjacent to the second step 22 with which the second movable measuring element 50 abuts. Furthermore, the inclination angle θ53 is larger than the inclination angle θ3 of the third surface 27 on the side farther from the opening end 12a. With this structure, the inclined surface 53 of the second movable measuring element 50 abuts the second step 22.

[0057] use Figure 8 A measurement method using the measurement jig 1 having the above-described configuration will be described. Figure 8 This is a schematic diagram showing the state of the measuring jig 1 during measurement. Before starting the measurement, the shaft 31 of the main body 30 is inserted from the open end 12a of the valve hole 12 into the guide hole 11a of the valve guide 11. This allows the main body 30 to move axially along the axis 11X of the guide hole 11a.

[0058] When the main body 30 is moved in the axial direction, the conical surface 33 of the reference gauge 32 of the main body 30 contacts the entire circumference of the first step 21 of the valve seat 20. This positions the reference gauge 32 relative to the valve seat 20.

[0059] When the reference measuring member 32 is positioned on the first step 21, the inclined surface 43 of the first movable measuring member 40 abuts against the first step 21. Here, when the first movable measuring member 40 moves relative to the reference measuring member 32, the amount of axial movement of the first movable measuring member 40 can be read on the display unit 74 of the first measuring instrument 71.

[0060] When the reference measuring member 32 is positioned on the first step 21, the inclined surface 53 of the second movable measuring member 50 abuts against the second step 22. At this time, when the second movable measuring member 50 moves relative to the reference measuring member 32, the amount of axial movement of the second movable measuring member 50 can be read on the display 78 of the second measuring instrument 75.

[0061] In this manner, the measurement jig 1 can obtain the axial movement of each of the first movable measuring element 40 and the second movable measuring element 50 relative to the reference measuring element 32. Thus, by knowing the inner diameter D1 of the first step 21 in advance, the inner diameter D2 of the second step 22 and the surface width W between the first and second step 21 and 22 can also be calculated.

[0062] As described above, according to this embodiment, when measuring the shape of a multi-step expanded hole using the measuring jig 1, the reference measuring piece 32 is positioned on the first step 21, and the movement of the second movable measuring piece 50 is measured based on the position where the reference measuring piece 32 abuts the first step 21. If the axial distance between the shaft 31 of the first step 21 and the second step 22 can be determined, the inner diameter of the second step 22 and the surface width W between the first and second steps 21 and 22 can also be calculated by previously knowing the inner diameter of the first step 21. This allows for the determination of multiple lengths in the hole shape. Furthermore, these measurements can be performed by directly inserting the measuring jig into a single multi-step expanded hole, eliminating the need for a separate contour measuring machine. This allows for efficient quality control on the production line. Consequently, efficient quality control of the multi-step expanded hole formed in the valve hole 12 is possible.

[0063] Furthermore, according to this embodiment, a first movable measuring piece 40 is used as a measuring piece in contact with the first step portion 21 in addition to the reference measuring piece 32. Because the reference measuring piece 32 has a conical tapered surface 33, it is positioned by contacting the entire circumference of the first step portion 21. In contrast, the first movable measuring piece 40 contacts a portion of the first step portion 21. By using multiple measuring pieces in different contact patterns to measure the first step portion 21, the reference step for measurement, the inner diameter D1 of the first step portion 21 can be measured more precisely. Furthermore, with this configuration, even when machining errors or fluctuations occur on the inner circumference of the hole when forming a multi-step diameter expansion hole, the measuring jig can be rotated by a predetermined angle each time, allowing the first movable measuring piece to detect multiple locations on the inner circumference of the hole, thereby more accurately measuring the inner diameter D2 of the second step portion 22 and the surface width W between the first and second steps 21 and 22.

[0064] Furthermore, according to this embodiment, the reference measuring element 32, the first movable measuring element 40, and the second movable measuring element 50 are retained by an O-ring 60. When the first movable measuring element 40 and the second movable measuring element 50 abut against the first step 21 and the second step 22, respectively, a restoring force is exerted by the elastic deformation of the O-ring 60. This restoring force acts as a measurement load, enabling precise measurement.

[0065] Furthermore, according to this embodiment, a multi-step expanded diameter hole is formed in the valve seat 20 disposed in the valve hole 12 of the engine cylinder head 10. The second surface 26 between the first step 21, which serves as a reference, and the second step 22, which is different from the first step 21, constitutes the abutment surface of the valve seat 20. This provides a measuring jig 1 that can precisely measure the surface width of the abutment surface of the valve seat.

[0066] Furthermore, according to this embodiment, inclined surfaces 33, 43, and 53 are formed on the reference measuring element 32, the first movable measuring element 40, and the second movable measuring element 50, respectively. The inclination angles θ33, θ43, and θ53 of the inclined surfaces 33, 43, and 53 are smaller than the angle of the inclined surface closer to the open end 12a of the two inclined surfaces adjacent to the stepped portions with which the measuring elements abut, and larger than the angle of the inclined surface farther from the open end. This allows the inclined surfaces of the measuring elements to directly abut the stepped portions, enabling precise measurement of the shape of multi-stage expanded holes.

[0067] Furthermore, the present invention is not limited to the described embodiment and can be implemented in various ways. In the above embodiment, the measuring instrument 70 is a micrometer that only displays the amount of movement of the measuring piece, but this is not a limitation. For example, a small computer including a processor and a storage unit can be attached to the measuring fixture 1, and the processor can automatically calculate the hole shape of the multi-stage expanded hole based on the amount of movement obtained by the measuring instrument 70. In this case, the processor uses the data of the inner diameter D1 of the first step portion 21 pre-set in the storage unit and the data of the amount of movement of the measuring piece obtained by the measuring instrument 70 to calculate the inner diameter D2 of the second step portion 22 and the surface width W of the abutment surface.

[0068] Label Description

[0069] 1…Measuring fixture

[0070] 10…Cylinder head

[0071] 11a…Guide hole (reference shaft hole)

[0072] 12…Valve hole (hole)

[0073] 12a…Open end

[0074] 20…valve seat

[0075] 21…First step (reference step)

[0076] 22…Second step (step different from the reference step)

[0077] 26…Side 2

[0078] 31…Shaft

[0079] 32…reference measuring piece

[0080] 33…conical surface (inclined surface)

[0081] 36…first groove portion (groove portion)

[0082] 37…Second groove (groove)

[0083] 38...Retaining groove 38

[0084] 40…First movable measuring member (reference movable measuring member)

[0085] 43… inclined surface

[0086] 48…Retention slot

[0087] 50…Second movable measuring piece (movable measuring piece)

[0088] 53… inclined surface

[0089] 58…Retention slot

[0090] 60…O-ring (elastic component)

[0091] 71 ...first measuring device (reference movement amount detection unit)

[0092] 75 ...Second measuring device (movement amount detecting unit).

Claims

1. A measuring jig for measuring the shape of a multi-stage enlarged hole, wherein the multi-stage enlarged hole is connected to the open end of a hole portion formed coaxially with a reference axial hole, is formed coaxially with the reference axial hole, has a plurality of stepped portions, and is expanded in stages, wherein the measuring jig is characterized in that: The measuring fixture has: a shaft portion inserted into the reference shaft hole; a reference measuring member provided integrally with the shaft portion and positioned on a reference step portion serving as a reference for measurement among the plurality of step portions; a movable measuring piece configured to be movable in the axial direction of the shaft portion relative to the outer peripheral surface of the reference measuring piece and to abut against a step portion different from the reference step portion among the plurality of step portions; as well as a movement amount detection unit for measuring the movement amount of the movable measuring member relative to the reference measuring member, The movement amount detection unit measures the movement amount of the movable measuring element based on a position where the reference measuring element contacts the reference step portion.

2. The measuring jig according to claim 1, wherein: The measuring fixture further comprises: a reference movable measuring piece configured to be movable in the axial direction of the shaft portion relative to the outer peripheral surface of the reference measuring piece and to abut against the reference step portion among the plurality of step portions; as well as a reference movement amount detection unit for measuring the movement amount of the reference movable measuring member relative to the reference measuring member; The reference movement amount detection unit measures the movement amount of the reference movable measurement element based on a position where the reference measurement element contacts the reference step portion.

3. The measuring jig according to claim 2, wherein: The reference movable measuring piece and the movable measuring piece are slidably arranged in two grooves formed on the outer peripheral surface of the reference measuring piece and are held relative to the reference measuring piece by an elastic member. Retention grooves for retaining the elastic member are formed on the outer peripheral surface of the reference measuring element, the outer peripheral surface of the reference movable measuring element, and the outer peripheral surface of the movable measuring element, respectively.

4. The measuring jig according to claim 1, wherein: The multi-stage expanded diameter hole is formed in a valve seat, and the valve seat is arranged in a valve hole of a cylinder head of an engine. A surface between the reference step portion and a step portion different from the reference step portion constitutes a contact surface of the valve seat.

5. The measuring jig according to claim 2, wherein: The plurality of step portions are formed by a plurality of continuous inclined surfaces whose inclination angles with respect to the shaft portion gradually increase as approaching the opening end. The reference measuring member, the reference movable measuring member, and the movable measuring member each have an inclined surface that abuts against the step portion. The inclined surfaces of the reference measuring piece, the reference movable measuring piece and the movable measuring piece are respectively formed with respect to the shaft portion in such a manner that the inclination angle is smaller than the inclination angle of the inclined surface on the side close to the opening end among the inclined surfaces adjacent to the step portion abutted by each measuring piece and is larger than the inclination angle of the inclined surface on the side away from the opening end.

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