CN115143858A

CN115143858A - Measuring clamp

Info

Publication number: CN115143858A
Application number: CN202210160193.1A
Authority: CN
Inventors: 畑山忠友; 福田敏彦
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2021-03-31
Filing date: 2022-02-22
Publication date: 2022-10-04
Also published as: JP2022155769A

Abstract

The invention provides a measuring jig which can efficiently manage the quality of a multistage-diameter-enlarged hole when the multistage-diameter-enlarged hole is formed on a valve seat. The measuring jig measures the hole shape of a multi-step diameter-enlarging hole formed coaxially with the guide hole at the opening end of the valve hole formed coaxially with the guide hole. The measuring jig has: a shaft portion inserted into the guide hole; a reference measuring member provided integrally with the shaft portion and positioned at a first stepped portion serving as a reference of measurement; a second movable measuring member disposed movably in the axial direction of the shaft portion with respect to the outer peripheral surface of the reference measuring member, and abutting against the second stepped portion; and a second measuring device for measuring the movement amount of the second movable measuring element relative to the reference measuring element. The second measuring device measures the movement amount of the second movable measuring element with reference to the position where the reference measuring element abuts against the first stepped portion.

Description

Measuring clamp

Technical Field

The present invention relates to a measuring jig for measuring a hole shape in the vicinity of an opening end of a valve hole.

Background

In recent development of automobiles with high output and low fuel consumption, it is important to achieve a good combustion state in a combustion chamber of an engine in order to improve combustion efficiency. Therefore, in order to manufacture a high-output and low-fuel-consumption engine, it is important to maintain the machining accuracy of parts on the production technology surfaces of a valve seat and a valve, which are assembled in a cylinder head of the engine, to be constant or higher.

As a structure for checking the machining accuracy of the valve hole, there is a structure as follows. In patent document 1, in order to measure the height of a cover portion formed in a part of the periphery of the open end of the valve hole, a measuring ring that moves relative to a positioning portion positioned at the open end of the valve hole is attached to the positioning portion. The height of the hood portion is measured by bringing a measuring ring into contact with the hood portion. In patent document 2, in order to measure the inner diameter of the shroud portion, a positioning portion positioned at an opening end of the valve hole is attached with a measuring piece that rotates around the positioning portion. The inner diameter of the cover portion is measured by abutting the measuring member against the inner wall of the cover portion while the measuring member is rotated around the positioning portion.

Documents of the prior art

Patent document

Patent document 1: japanese unexamined patent publication No. 2014-062811

Patent document 2: japanese patent laid-open No. 2014-055888

Disclosure of Invention

Problems to be solved by the invention

However, the machining accuracy of the abutment surface of the valve seat and the valve affects the sealing of the combustion chamber and the accuracy of the operation of the valve train mechanism, and therefore, higher machining accuracy than that of the shroud portion is required. In addition, in recent years, the contact surface of the valve seat may become a multi-step diameter-enlarged hole, and the contact surface of the valve seat becomes complicated, and therefore, higher machining accuracy is required. In the case of performing such inspection of the machining accuracy of the stepped-diameter hole, the hole shape of the stepped-diameter hole cannot be precisely measured by the above-described method.

Therefore, when measuring the hole shape of the multi-step enlarged hole, a profile shape measuring machine, which is a general-purpose precision measuring machine, is used. However, in order to perform inspection by the contour shape measuring machine, it is necessary to transport the cylinder head from the production line to the outside of the production line, or to remove the valve seat from the valve hole, transport the cylinder head to a clean room or the like, and transport the cylinder head to the contour shape measuring machine, and it is necessary to perform work man-hours, time, and the like, and it is difficult to efficiently perform quality control.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a measuring jig capable of efficiently performing quality control of a multistage-enlarged hole when the multistage-enlarged hole is formed in a valve seat.

Means for solving the problems

In order to achieve the object, the invention according to claim 1 is a measuring jig (1) for measuring a hole shape of a multi-step enlarged hole which is formed coaxially with a reference shaft hole (guide hole 11 a) at an opening end (12 a) of a hole portion (valve hole 12) formed coaxially with the reference shaft hole, and which is enlarged in diameter in stages with a plurality of stepped portions formed thereon, the measuring jig including: a shaft portion (31) inserted into the reference shaft hole; a reference measuring piece (32) which is provided integrally with the shaft portion and is positioned at a reference stepped portion (first stepped portion 21) which is a reference of measurement among the plurality of stepped portions; a movable sensing member (a second movable sensing member 50) which is disposed so as to be movable in the axial direction of the shaft portion with respect to the outer peripheral surface of the reference sensing member, and which abuts against a step portion (a second step portion 22) different from the reference step portion among the plurality of step portions; and a movement amount detecting portion (second measuring instrument 75) that measures a movement amount of the movable measuring element with respect to the reference measuring element, the movement amount detecting portion measuring a movement amount of the movable measuring element with reference to a position where the reference measuring element abuts against the reference stepped portion.

In this way, when measuring the hole shape of the multi-step enlarged hole, the amount of movement of the movable measuring piece is measured with reference to the position where the reference measuring piece abuts against the reference stepped portion in a state where the reference measuring piece is positioned at the reference stepped portion. If the axial distance between the reference stepped portion and the shaft portion of the stepped portion different from the reference stepped portion can be grasped, the inner diameter of the stepped portion different from the reference stepped portion and the surface width between the reference stepped portion and the stepped portion different from the reference stepped portion can be calculated by grasping the inner diameter of the reference stepped portion in advance. Therefore, a plurality of lengths in the hole shape can be grasped. In addition, since these measurements can be performed by directly inserting the measurement jig into the multi-step diameter-enlarging hole, and a profile measuring machine is not required to be separately used, quality control can be efficiently performed on the production line. Therefore, the quality control of the multistage-diameter-enlarged hole can be efficiently performed.

An invention according to claim 2 is the measuring jig according to claim 1, further comprising: a reference movable measuring piece (a first movable measuring piece 40) which is disposed so as to be movable in the axial direction of the shaft portion with respect to an outer peripheral surface of the reference measuring piece, and which abuts against the reference stepped portion of the plurality of stepped portions; and a reference movement amount detecting unit (first measuring device 71) that measures a movement amount of the reference movable measuring element with respect to the reference measuring element, wherein the reference movement amount detecting unit measures movement amounts of the reference movable measuring element and the movable measuring element with reference to a position where the reference measuring element abuts against the reference stepped portion.

In this way, by using the reference movable measuring element in addition to the reference measuring element as the measuring element that is brought into contact with the reference stepped portion, the inner diameter of the reference stepped portion can be measured more precisely. Therefore, the inner diameter of the stepped portion different from the reference stepped portion and the surface width between the reference stepped portion and the stepped portion different from the reference stepped portion can be measured more precisely.

An invention according to claim 3 is characterized in that, in the measuring jig according to claim 2, the reference movable sensing piece and the movable sensing piece are slidably disposed in 2 groove portions (a first groove portion 36 and a second groove portion 37) formed in an outer peripheral surface of the reference sensing piece, and are held by an elastic member (O-ring 60) with respect to the reference sensing piece, and holding grooves (38, 48, 58) for holding the elastic member are formed in an outer peripheral surface of the reference sensing piece, an outer peripheral surface of the reference movable sensing piece, and an outer peripheral surface of the movable sensing piece, respectively.

In this way, when the reference measuring piece, the reference movable measuring piece, and the movable measuring piece are held by the elastic member, the restoring force acts by the elastic deformation of the elastic member when the reference movable measuring piece, the movable measuring piece, and the stepped portion are brought into contact with each other. This restoring force becomes a measurement load, and can be measured accurately.

An invention according to claim 4 is characterized in that, in the measuring jig according to any one of claims 1 to 3, the multistage diameter-expanding hole is formed in a valve seat (20) disposed in a valve hole (12) of a cylinder head (10) of an engine, and a surface (second surface 26) between the reference stepped portion and a stepped portion different from the reference stepped portion constitutes an abutment surface of the valve seat.

In this way, the multistage diameter-expanding hole is formed in the valve seat disposed in the valve hole of the cylinder head of the engine, and a surface between the reference stepped portion and the stepped portion different from the reference stepped portion constitutes an abutment surface of the valve seat. This enables the surface width of the contact surface of the valve seat to be precisely measured.

The invention according to claim 5 is characterized in that, in the measurement jig according to any one of claims 1 to 4, the plurality of step portions are formed by a plurality of continuous inclined surfaces whose inclination angles with respect to the shaft portion become larger in stages as approaching the opening end, the reference measuring piece, the reference movable measuring piece, and the movable measuring piece each have an inclined surface (33, 43, 53) which abuts against the step portion, and the inclined surfaces of the reference measuring piece, the reference movable measuring piece, and the movable measuring piece each have an inclination angle with respect to the shaft portion formed so as to be smaller than an inclination angle of an inclined surface on a side closer to the opening end and larger than an inclination angle of an inclined surface on a side farther from the opening end among inclined surfaces adjacent to the step portion with which each measuring piece abuts.

In this way, the inclination angles of the inclined surfaces formed on the reference measuring element, the reference movable measuring element, and the movable measuring element are formed to be smaller than the inclination angle of the inclined surface on the side closer to the opening end and larger than the inclination angle of the inclined surface on the side farther from the opening end. Thus, the inclined surface of each measuring tool directly contacts each stepped portion, and the hole shape of the multi-step diameter-enlarged hole can be accurately measured.

Drawings

Fig. 1 is a diagram showing the overall configuration of the measurement jig and the positional relationship of the measurement jig with respect to the valve hole.

Fig. 2 is a view showing the entire configuration of the measurement jig seen from the direction a of fig. 1.

Fig. 3 is a diagram showing the structures of the first movable sensing member and the second movable sensing member, (a) is a structural diagram of the first movable sensing member, and (B) is a structural diagram of the second movable sensing member.

Fig. 4 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.

Fig. 5 is a diagram showing a state of the O-ring when the valve seat abuts against the first movable measuring element, (a) is a diagram showing a state before abutment, and (B) is a diagram showing a state at the time of abutment.

Fig. 6 is a sectional view showing a detailed structure of the valve seat.

Fig. 7 is a diagram showing the inclination angle of the valve seat and the inclination angle of the measuring element, (a) is a diagram showing the taper angle of the reference measuring element, (B) is a diagram showing the inclination angle of the first movable measuring element, and (C) is a diagram showing the inclination angle of the second movable measuring element.

FIG. 8 is a schematic view showing the state of a measuring jig during measurement.

Detailed Description

Hereinafter, the measuring jig 1 according to the first embodiment of the present invention will be described in detail with reference to the drawings. In the following description, in order to facilitate understanding of the structure of the valve hole 12 and the valve seat 20 of the cylinder head 10, a description will be given using a diagram in which the opening is directed upward. In the following description, the upper or lower case means the upper or lower case in the drawings unless otherwise specified. The axial direction is a direction parallel to the direction of the axis 11X of the guide hole 11a (the axial direction of the shaft 31).

The structure of the measuring jig 1 and the relationship with the vicinity of the valve hole 12 of the cylinder head 10 will be described with reference to fig. 1. Fig. 1 is a diagram showing the overall configuration of the measurement jig 1 and the positional relationship of the measurement jig 1 with respect to the valve hole 12. The measuring jig 1 measures the hole shape of the valve seat 20 disposed at the open end 12a of the valve hole 12 formed in the cylinder head 10 of the engine.

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. On the opposite side (lower side in the figure) of the valve hole 12 from the open end 12a, a guide hole 11a of the valve guide 11 is formed. The guide hole 11a is a hole into which a shaft of a valve, not shown, is inserted when the cylinder head 10 is used. The valve moves in the axial direction along the axis 11X of the guide hole 11a, and performs intake and exhaust of air from the cylinder head 10 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 disposed at the open end 12a of the valve hole 12. The valve seat 20 is formed with a multistage diameter-enlarging hole having a plurality of stepped portions and stepwise diameter enlargement. The plurality of step portions are formed in a circular shape when viewed from the open end 12a side. The detailed description of the multi-step enlarged bore will be described later.

The structure of the measurement jig 1 will be described with reference to fig. 1 and 2. Fig. 2 is a view showing the entire configuration of the measurement jig as viewed from the direction a of fig. 1. The measuring jig 1 is configured such that the first movable sensing member 40 and the second movable sensing member 50 are held by the body portion 30 via the O-ring 60, and the measuring device 70 measures the amount of movement of the first movable sensing member 40 and the second movable sensing member 50.

The main body portion 30 includes a shaft portion 31 inserted into the guide hole 11a, a reference probe 32 positioned with respect to the valve seat 20, and a probe holding portion 35 for fixedly holding the probe 70, and these components are integrally provided.

The shaft portion 31 is formed by a shaft diameter fitted into the guide hole 11a of the valve guide 11. Thereby, the shaft portion 31 slides along the guide hole 11a, and the body portion 30 can be moved in the axial direction along the axis 11X of the guide hole 11a.

The cross section of the reference measuring piece 32 on the plane orthogonal to the axis 11X is formed in a substantially circular shape (see fig. 4) centering on the axis 11X, and the entire structure is formed in a cylindrical shape. A conical tapered surface 33 having a diameter that increases continuously with distance from the shaft portion 31 is formed at an end portion (lower end portion) of the reference measuring probe 32 on the shaft portion 31 side. A first groove portion 36 and a second groove portion 37 formed to extend in the axial direction are formed on the outer peripheral surface (side surface in the drawing) of the reference measuring piece 32. The first groove 36 is provided with a first movable sensing member 40, and the second groove 37 is provided with a second movable sensing member 50. Further, a holding groove 38 is formed in the circumferential direction on the outer peripheral surface of the reference probe 32. An O-ring 60 is accommodated in the retaining groove 38 in the circumferential direction. Thus, the holding groove 38 holds the O-ring 60.

The measuring instrument holding portion 35 has a cylindrical outer appearance, and fixedly holds the measuring instrument 70. Specifically, the

substrates

72 and 76 of the measuring instrument 70 are inserted through the through-holes 35h penetrating in the vertical direction of the measuring instrument holding portion 35. Thereafter, a bolt (not shown) is inserted into the holding hole 35b through an opening 35a (see fig. 2) formed in the side surface of the measuring instrument holding portion 35, and the

bases

72 and 76 are pressed and fixed by the tip of the bolt. Thus, the measuring instrument holding unit 35 fixedly holds the measuring instrument 70.

The measuring device 70 is a dial gauge of a standard type. The measuring device 70 of the present embodiment includes a first measuring device 71 and a second measuring device 75. The first measuring instrument 71 includes a base 72, a measuring rod 73 having a tip end 73a, and a display 74. The measurement rod 73 is configured to be extendable and retractable in the axial direction with respect to the base 72, and a distal end portion 73a of the measurement rod 73 is configured to contact the first movable probe 40. With this configuration, the amount of movement measured by the movement of the measurement lever 73 is displayed on the display unit 74. The display unit 74 is provided with a needle 74a and a dial 74b (scale marks not shown) that rotate about the central axis in accordance with the axial movement of the measuring rod 73. The value of the scale indicated by the needle 74a is measured as the amount of movement of the first movable sensing member 40.

The second measuring instrument 75 includes a base 76, a measuring rod 77 having a tip end portion 77a, and a display portion 78. The second measuring device 75 has the same configuration as the first measuring device 71, and therefore, detailed description thereof is omitted. The configuration of the measuring instrument 70 is not limited to this, and may not be a dial indicator as long as it can measure the axial movement amount of the first movable measuring element 40 and the second movable measuring element 50.

The structure of the movable sensing member will be described with reference to fig. 3. Fig. 3 is a diagram showing the structure of the first movable sensing member 40 and the second movable sensing member 50, fig. 3 (a) is a structural diagram of the first movable sensing member 40, and fig. 3 (B) is a structural diagram of the second movable sensing member 50.

The first movable measuring element 40 has a flat surface 41 formed on a surface thereof abutting on the distal end portion 73a of the measuring rod 73 of the first measuring device 71, and an inclined surface 43 formed on a surface thereof abutting on the stepped bore of the valve seat 20. The sliding surface 45 facing the first groove portion 36 of the reference measuring member 32 and configured to be slidable with respect to the first groove portion 36 is formed as a surface parallel to the axial direction, and a holding groove 48 for holding an O-ring 60 is formed on the surface of the reference measuring member 32 in the outer diameter direction.

The second movable measuring element 50 has a flat surface 51 formed on a surface thereof abutting on the distal end portion 77a of the measuring rod 77 of the second measuring device 75, and an inclined surface 53 formed on a surface thereof abutting on the stepped bore of the valve seat 20. Further, a sliding surface 55 configured to face the second groove portion 37 of the reference measuring piece 32 and to be slidable with respect to the second groove portion 37 is formed as a surface parallel to the axial direction, and a holding groove 58 for holding an O-ring 60 is formed on a surface in the outer diameter direction of the reference measuring piece 32.

The structure in which the movable measuring element is held by the reference measuring element will be described with reference to fig. 4. Fig. 4 is a diagram showing a state in which the first movable sensing member 40 and the second movable sensing member 50 are held by the reference sensing member 32. When viewed from the direction (axially upward) of fig. 4, the first movable sensing member 40 is disposed so as to be fitted into the first groove portion 36 of the reference sensing member 32, and the portion of the first movable sensing member 40 where the holding groove 48 is formed protrudes from the outer periphery of the reference sensing member 32. Similarly, the second movable sensing member 50 is disposed so as to be fitted into the second groove portion 37 of the reference sensing member 32, and a portion of the second movable sensing member 50 where the holding groove 58 is formed protrudes from the outer periphery of the reference sensing member 32. In this state, the O-ring 60 received and held in the holding groove 38 of the reference sensing member 32 is bridged between the holding groove 48 of the first movable sensing member 40 and the holding groove 58 of the second movable sensing member 50. Thereby, the first movable sensing member 40 and the second movable sensing member 50 are held by the reference sensing member 32.

In the present embodiment, the holding members of the first movable sensing member 40 and the second movable sensing member 50 are O-rings 60, but the present invention is not limited thereto. However, since the holding member needs to be elastically deformed, the holding member is constituted by at least some elastic member.

Fig. 5 shows the state of the O-ring 60 during measurement. Fig. 5 is a diagram showing a state of the O-ring 60 when the valve seat 20 abuts against the first movable sensing member 40, fig. 5 (a) is a diagram showing a state before abutment, and fig. 5 (B) is a diagram showing a state at the time of abutment.

As shown in fig. 5 (a), before the valve seat 20 abuts the first movable sensing member 40, the load from the valve seat 20 is not applied to the O-rings 60 held in the holding groove 38 of the reference sensing member 32 and the holding groove 48 of the first movable sensing member 40. As shown in fig. 5 (B), when the valve seat 20 abuts on the first movable sensing member 40, the valve seat 20 pushes up the first movable sensing member 40. Thus, the O-ring 60 is elastically deformed by being sandwiched between the holding groove 38 of the reference sensing member 32 and the holding groove 48 of the first movable sensing member 40. The O-ring 60 generates a restoring force by being elastically deformed. This restoring force becomes a measurement load. Note that the state of the O-ring 60 when the valve seat 20 abuts against the second movable sensing member 50 is the same as that when the O-ring abuts against the first movable sensing member 40, and therefore, the description thereof is omitted.

The hole shape of the multi-step diameter-enlarged hole formed in the valve seat 20 to be measured will be described in detail with reference to fig. 6. Fig. 6 is a sectional view showing the detailed structure of the valve seat 20. The multistage diameter-enlarged hole formed in the valve seat 20 is formed by a plurality of continuous inclined surfaces whose inclination angles with respect to the axis 11X of the guide hole 11a become gradually larger as approaching the open end 12a from one side of the shaft portion 31 approaching the valve hole 12, and a portion where the inclination angle changes becomes a stepped portion.

The plurality of step portions formed on the valve seat 20 have a first step portion 21, a second step portion 22, and a third step portion 23 as proceeding downward in the drawing from the open end 20a of the valve seat 20 on the open end 12a side of the valve hole 12, and are adjacent to each other in this order. When viewed from the axial direction, the stepped portions are all formed in a circular shape. The first step portion 21 has an inner diameter D1, and the second step portion 22 has an inner diameter D2.

Further, the plurality of step portions of the valve seat 20 are inclined surfaces having a predetermined inclination angle with respect to the axis 11X of the guide hole 11a. Specifically, the first surface 25, the second surface 26, and the third surface 27 are formed so as to extend downward in the drawing from the open end 20a of the valve seat 20 on the open end 12a side of the valve hole 12, and are adjacent to each other in this order. The first surface 25 is formed between the open end 20a and the first stepped portion 21, the second surface 26 is formed between the first stepped portion 21 and the second stepped portion 22, and the third surface 27 is formed between the second stepped portion 22 and the third stepped portion 23.

Here, the second surface 26 constitutes an abutment surface of the valve seat 20. Since the contact surface is a surface against which the valve contacts, it is preferable to grasp the dimension in detail. Specifically, the surface width W of the contact surface is a width between the inner diameter of the first stepped portion 21 and the inner diameter of the second stepped portion 22 in the contact surface.

The multistage enlarged hole is a plurality of continuous inclined surfaces whose inclination angle with respect to the axis line 11X of the guide hole 11a gradually increases as approaching the open end 12a from one of the shaft portions 31 approaching the valve hole 12. Therefore, when the inclination angle of the first surface 25 is the inclination angle θ 1, the inclination angle of the second surface 26 is the inclination angle θ 2, and the inclination angle of the third surface 27 is the inclination angle θ 3, the relationship of θ 1 > θ 2 > θ 3 is established.

Next, the relationship between the inclination angle of the valve seat and the inclination angle of the sensing piece is shown. Fig. 7 is a diagram showing a relationship between the inclination angle of the valve seat and the inclination angle of the sensing piece, fig. 7 (a) is a diagram showing the taper angle (inclination angle) of the reference sensing piece 32, fig. 7 (B) is a diagram showing the inclination angle of the first movable sensing piece 40, and fig. 7 (C) is a diagram showing the inclination angle of the second movable sensing piece 50.

As shown in fig. 7 (a), the tapered surface 33 of the reference probe 32 has a taper angle θ 33 with respect to the axis 11X of the guide hole 11a. Specifically, the taper angle θ 33 is formed smaller than the inclination angle θ 1 of the first surface 25 on the side closer to the open end 12a among the inclined surfaces (the first surface 25 and the second surface 26) adjacent to the first step portion 21 with which the reference measuring piece 32 abuts. The taper angle θ 33 is formed larger than the inclination angle θ 2 of the second surface 26 on the side away from the open end 12 a. With this configuration, the tapered surface 33 of the reference measuring piece 32 abuts on the first stepped portion 21.

As shown in fig. 7 (B), the inclined surface 43 of the first movable sensing member 40 has an inclination angle θ 43 with respect to the axis 11X of the guide hole 11a. Specifically, the inclination angle θ 43 is formed smaller than the inclination angle θ 1 of the first surface 25 on the side closer to the open end 12a out of the inclined surfaces (the first surface 25 and the second surface 26) adjacent to the first stepped portion 21 with which the first movable sensing piece 40 abuts. The inclination angle θ 43 is formed larger than the inclination angle θ 2 of the second surface 26 on the side away from the open end 12 a. With this structure, the inclined surface 43 of the first movable sensing piece 40 abuts against the first stepped portion 21.

As shown in fig. 7 (C), the inclined surface 53 of the second movable sensing member 50 has an inclination angle θ 53 with respect to the axis 11X of the guide hole 11a. Specifically, the inclination angle θ 53 is formed smaller than the inclination angle θ 2 of the second surface 26 on the side closer to the opening end 12a out of the inclined surfaces (the second surface 26 and the third surface 27) adjacent to the second stepped portion 22 with which the second movable sensing piece 50 abuts. The inclination angle θ 53 is formed larger than the inclination angle θ 3 of the third surface 27 on the side away from the opening end 12 a. With this structure, the inclined surface 53 of the second movable sensing piece 50 abuts against the second stepped portion 22.

A measurement method of the measurement jig 1 configured as described above will be described with reference to fig. 8. Fig. 8 is a schematic diagram showing a state of the measurement jig 1 at the time of measurement. Before the measurement is started, the shaft 31 of the body 30 is inserted into the guide hole 11a of the valve guide 11 from the opening end 12a of the valve hole 12. Thereby, the body portion 30 can move in the axial direction along the axis 11X of the guide hole 11a.

When the main body 30 is moved in the axial direction, the tapered surface 33 of the reference measuring piece 32 of the main body 30, which is formed in a conical shape, abuts against the entire circumference of the first stepped portion 21 of the valve seat 20. Thereby, the reference sensing member 32 is positioned relative to the valve seat 20.

In a state where the reference measuring member 32 is positioned at the first stepped portion 21, the inclined surface 43 of the first movable measuring member 40 abuts on the first stepped portion 21. Here, when the first movable sensing member 40 moves relative to the reference sensing member 32, the amount of movement in the axial direction of the first movable sensing member 40 can be read by the display portion 74 of the first measuring instrument 71.

In a state where the reference measuring member 32 is positioned at the first stepped portion 21, the inclined surface 53 of the second movable measuring member 50 abuts against the second stepped portion 22. At this time, when the second movable sensing member 50 moves relative to the reference sensing member 32, the amount of movement in the axial direction of the second movable sensing member 50 can be read by the display portion 78 of the second measuring instrument 75.

In this way, in the measurement jig 1, the amount of movement of each of the first movable sensing element 40 and the second movable sensing element 50 in the axial direction with respect to the reference sensing element 32 can be obtained. Thus, by grasping the inner diameter D1 of the first stepped portion 21 in advance, the inner diameter D2 of the second stepped portion 22 and the surface width W between the first stepped portion 21 and the second stepped portion 22 can be calculated.

As described above, according to the present embodiment, when the hole shape of the stepped hole is measured by the measuring jig 1, the movement amount of the second movable measuring part 50 is measured with the position where the reference measuring part 32 abuts against the first stepped part 21 as a reference in a state where the reference measuring part 32 is positioned at the first stepped part 21. If the axial distance between the first stepped portion 21 and the shaft portion 31 of the second stepped portion 22 can be grasped, the inner diameter of the second stepped portion 22 and the surface width W between the first stepped portion 21 and the second stepped portion 22 can be calculated by grasping the inner diameter of the first stepped portion 21 in advance. Therefore, a plurality of lengths in the hole shape can be grasped. In addition, these measurements can be performed by directly inserting the measurement jig into the 1-step multi-diameter hole, and there is no need to separately use a contour shape measuring machine, so that quality control can be efficiently performed on the production line. Therefore, the quality control of the multi-stage diameter-enlarged hole formed in the valve hole 12 can be performed efficiently.

Further, according to the present embodiment, as the measuring member that comes into contact with the first stepped portion 21, the first movable measuring member 40 is used in addition to the reference measuring member 32. Since the reference measuring piece 32 has the conical tapered surface 33, it is positioned by abutting against the entire circumference of the first stepped portion 21. In contrast, the first movable sensing member 40 abuts against a part of the first stepped portion 21. In this way, by measuring the first stepped portion 21, which is a reference stepped portion for measurement, using a plurality of measuring parts that are brought into contact with each other in different ways, the inner diameter D1 of the first stepped portion 21 can be measured more precisely. Further, according to this configuration, even when a machining error, undulation, or the like occurs in the inner peripheral surface of the hole when the hole shape of the multistage enlarged diameter hole is formed, the inner diameter D2 of the second stepped portion 22 and the surface width W between the first stepped portion 21 and the second stepped portion 22 can be measured more precisely by detecting a plurality of portions of the inner peripheral surface of the hole by the first movable measuring piece each time the measurement jig is rotated by a predetermined angle.

In addition, according to the present embodiment, the reference measuring member 32, the first movable measuring member 40, and the second movable measuring member 50 are held by the O-ring 60. When the first movable sensing member 40 and the second movable sensing member 50 are in contact with the first stepped portion 21 and the second stepped portion 22, respectively, the elastic deformation of the O-ring 60 causes a restoring force to act. This restoring force becomes a measurement load, and can be measured accurately.

In addition, according to the present embodiment, the multistage diameter-expanding hole is formed in the valve seat 20 disposed in the valve hole 12 of the cylinder head 10 of the engine. A second surface 26 between the first stepped portion 21 serving as a reference and the second stepped portion 22 different from the first stepped portion 21 constitutes an abutment surface of the valve seat 20. This makes it possible to provide the measuring jig 1 for accurately measuring the surface width of the abutment surface of the valve seat.

In addition, according to the present embodiment, the

inclined surfaces

33, 43, and 53 are formed on the reference measuring part 32, the first movable measuring part 40, and the second movable measuring part 50, respectively. The inclined surfaces 33, 43, 53 have inclination angles θ 33, θ 43, θ 53 smaller than the inclination angle of the inclined surface on the side closer to the open end 12a and larger than the inclination angle of the inclined surface on the side farther from the open end among the 2 inclined surfaces adjacent to the respective step portions with which the respective measuring elements are in contact. Thus, the inclined surface of each measuring tool directly contacts each stepped portion, and the hole shape of the multi-step diameter-enlarged hole can be accurately measured.

The present invention is not limited to the embodiments described above, and can be implemented in various ways. In the above-described embodiment, the measuring instrument 70 is a dial indicator and displays only the movement amount of the measuring instrument, but the present invention is not limited thereto. For example, the measurement jig 1 may be provided with a small-sized computer having a processor and a storage unit, and the processor may be configured to automatically calculate the hole shape of the multi-step enlarged hole based on the amount of movement obtained by the measuring instrument 70. In this case, the processor calculates the inner diameter D2 of the second stepped portion 22 and the surface width W of the contact surface using data of the inner diameter D1 of the first stepped portion 21 preset in the storage portion and data of the amount of movement of the probe acquired by the measuring instrument 70.

Description of the reference symbols

1-8230and measuring clamp

10 8230a cylinder cover

11 a' \ 8230and guide hole (reference axle hole)

12' \ 8230and valve hole (hole part)

12a 8230and open end

20 \ 8230and valve seat

21 '\ 8230'; first step part (reference step part)

22' \ 8230and a second step part (a step part different from the reference step part)

26 \ 8230and a second face

31 8230a shaft part

32 \8230andreference measuring and fixing piece

33' \ 8230and a conical surface (inclined surface)

36' \ 8230and the first groove part (groove part)

37 \ 8230and a second groove part (groove part)

38' \ 8230and holding groove 38

40 '\ 8230'; first movable measuring member (reference movable measuring member)

43 \ 8230and inclined plane

48 8230j holding groove

50 '\ 8230'; second movable measuring piece (movable measuring piece)

53 \ 8230and inclined plane

58 \ 8230and holding groove

60' \ 8230and O-shaped ring (elastic component)

71 8230a first measuring instrument (reference movement amount detecting section)

75 8230a second measuring device (movement amount detecting section).

Claims

1. A measuring jig for measuring a hole shape of a multi-step enlarged hole which is connected to an opening end of a hole portion formed coaxially with a reference shaft hole, is formed coaxially with the reference shaft hole, has a plurality of stepped portions formed therein, and is gradually enlarged in diameter,

the measurement jig has:

a shaft portion inserted into the reference shaft hole;

a reference measuring piece which is provided integrally with the shaft portion and is positioned at a reference stepped portion which becomes a reference for measurement among the plurality of stepped portions;

a movable sensing member that is disposed so as to be movable in an axial direction of the shaft portion with respect to an outer peripheral surface of the reference sensing member, and that abuts against a step portion different from the reference step portion among the plurality of step portions; and

a movement amount detecting unit that measures a movement amount of the movable measuring element with respect to the reference measuring element,

the movement amount detecting unit measures a movement amount of the movable sensing member with reference to a position where the reference sensing member abuts the reference stepped portion.

2. The assay holder of claim 1,

the measurement jig further has:

a reference movable measuring member disposed so as to be movable in an axial direction of the shaft portion with respect to an outer peripheral surface of the reference measuring member, and abutting against the reference stepped portion of the plurality of stepped portions; and

a reference movement amount detecting unit that measures a movement amount of the reference movable measuring element with respect to the reference measuring element,

the reference movement amount detecting unit measures the reference movable sensing member and the movement amount of the movable sensing member with reference to a position where the reference sensing member abuts against the reference stepped portion.

3. The assay holder of claim 2,

the reference movable sensing member and the movable sensing member are slidably disposed in 2 groove portions formed on an outer peripheral surface of the reference sensing member and held by an elastic member with respect to the reference sensing member,

a holding groove for holding the elastic member is formed in each of an outer peripheral surface of the reference measuring member, an outer peripheral surface of the reference movable measuring member, and an outer peripheral surface of the movable measuring member.

4. The assay holder of claim 1,

the multistage expanding hole is formed in a valve seat disposed in a valve hole of a cylinder head of the engine,

a surface between the reference stepped portion and a stepped portion different from the reference stepped portion constitutes an abutment surface of the valve seat.

5. The assay holder of claim 2,

the plurality of step portions are formed by a plurality of continuous inclined surfaces whose inclination angles with respect to the shaft portion become gradually larger as approaching the open end,

the reference measuring member, the reference movable measuring member, and the movable measuring member each have an inclined surface that abuts against the stepped portion,

the inclined surfaces of the reference measuring piece, the reference movable measuring piece, and the movable measuring piece are inclined relative to the shaft portion so that the inclination angle of each of the inclined surfaces is smaller than the inclination angle of the inclined surface on the side closer to the opening end and larger than the inclination angle of the inclined surface on the side farther from the opening end.