JP2008232734A - Measurement method and measurement apparatus of cylinder bore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fasten a cylinder head and a bearing cap member to a cylinder block when a roundness of a cylinder bore is measured in an engine, implement a measurement in a state that an actual operating condition of the engine is approximated, and obtain accurate roundness measurement data in the operating condition of the engine. <P>SOLUTION: A cylinder assembly 9 is obtained by assembling the cylinder head 3 and the bearing cap member to the cylinder block 1 in the to-be-measured engine by bolts, and installed so as to place the bearing cap member 8 on the upper side. A high-temperature fluid is fed into a water jacket. The operation condition of the engine is reproduced by inserting a measurement apparatus 20 into the cylinder bore 2 from the upside of the assembly 9 and implementing the measurement in this state. The roundness for reflecting an internal stress and an effect of a thermal expansion can be measured. A placement block 21 is bridged across a main bearing section so as to install the measurement apparatus 20. A positioning reference member 22 is provided and matched with the cylinder bore 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measuring method for measuring roundness and the like of a cross section of a cylindrical cylinder bore formed in a cylinder block of an engine, and a measuring apparatus suitable for the measuring method.

  In a reciprocating engine such as a gasoline engine or a diesel engine, fuel is burned in a cylinder bore formed in a cylinder block, and a piston is reciprocated to generate power. In recent years, in engines for vehicles, the demand for energy saving and improvement in fuel consumption has made the engines smaller and lighter, and the use of light metals such as aluminum and thinning of the cylinder blocks has also been promoted. It has been.

  A piston is inserted into the cylinder bore, and a piston ring fitted into the piston slides on the inner peripheral surface of the cylinder bore. The cylinder bore has a circular cross-section, but if the cylinder bore is distorted by an external force or the like and its roundness is reduced, the piston ring will come into contact with one piece and the sliding friction resistance will increase, resulting in an increase in engine mechanical loss. Deteriorate fuel consumption rate. Further, since the clearance between the cylinder bore and the piston ring is increased, the combustion gas blown through the crankcase of the engine, that is, the blow-by gas increases. Since blow-by gas contains unburned components such as HC (hydrocarbon), harmful components of engine exhaust gas increase when leaking from the crankcase.

  In this way, the roundness of the cylinder bore has a significant effect on the engine performance. Therefore, the roundness of the machine tool can be managed by measuring the roundness of the cylinder bore after machining, and the roundness can be used to develop machining methods. Such data has been conventionally obtained. In order to measure the roundness of a cylinder bore, usually a measuring sensor is inserted along the central axis from above the cylinder bore, and the distance from the central axis to the inner peripheral surface of the cylinder bore is measured while rotating the measuring sensor. To find the roundness. The measurement sensor is configured to be movable in the vertical direction, and the circularity of the cylinder bore can be obtained by measuring the roundness at a plurality of positions in the vertical direction. Such a measuring device is disclosed in Japanese Patent Laid-Open No. 7-270153 as an example.

By the way, in an actual engine, the cylinder head is firmly fastened to the cylinder block by a fastening bolt, so that an internal stress is generated around the cylinder bore and the cylinder bore is distorted. In general, a water-cooled engine in which a water jacket is provided on a cylinder block and a cylinder head is used as an engine for a vehicle. During operation of the engine, the temperature of the cylinder block or the like is increased by high-temperature combustion gas. As the temperature rises, the heat is transmitted to the cooling water circulating in the water jacket, and the temperature of the cooling water also rises. That is, during the operation of the engine, thermal expansion and thermal stress accompanying the temperature rise of the cooling water or the like are also generated around the cylinder bore.
The above measuring method for measuring roundness and cylindricity is to measure the roundness etc. in the state of a cylinder block alone by removing the cylinder head in order to insert the measuring sensor from above the cylinder bore. And measurement is performed in the state of normal temperature. For this reason, the obtained measurement results are different from the roundness in the engine assembly state in which the cylinder head is fastened, and no consideration is given to the change in roundness due to thermal expansion during engine operation. .

  As disclosed in Japanese Patent Application Laid-Open No. 2006-275760, the present applicant, when measuring the roundness or cylindricity of the cylinder bore, approximates the cylinder block to the actual operating state of the engine and performs measurement in that state. Then, we developed a measurement method to find the exact roundness in the engine operating state. In this measuring method, as shown in FIG. 9, the cylinder block 1 and the cylinder head 3 of the engine to be measured are assembled by fastening bolts 4 to form an assembly 9, and this is placed on a table 10 so that the cylinder block 1 is on the upper side. Install. This state is a state opposite to the engine posture when mounted on a vehicle or the like, and a semicircular concave portion 71 of the main bearing portion below the cylinder block 1 is present on the upper surface. A high-temperature fluid is sent from the high-temperature oil tank 14 to the water jackets 5 and 6 of the cylinder block 1 and the cylinder head 3 by the pump 13. In the fluid circulation circuit, 11 and 12 are water jacket inlet / outlet pipes, 15 is an electric heater, 16 is a flow rate adjusting valve, 17 and 18 are thermometers, and 19 is a pressure gauge.

The measuring device 20 is provided with a spline shaft 29 extending downward along the central axis of the cylinder bore 2, and a measuring sensor 24 is attached to the spline shaft 29. The measurement sensor 24 is a non-contact sensor that measures the distance to the inner peripheral surface of the cylinder bore 2 and is configured to be rotatable about the spline shaft 29 and to be movable in the vertical direction. The measuring device 20 is provided with a first reference member 20A that matches the inner peripheral surface of the cylinder bore 2, and a second reference member 20B that matches the recess 71 of the main bearing portion of the cylinder block 2.
The measuring device 20 is installed on the cylinder block 1 so that the second reference member 20B is fitted into the adjacent concave portion of the main bearing portion, and the first reference member 20A is brought into contact with the inner peripheral surface of the cylinder bore 2 for measurement. The spline shaft 29 to which the sensor 24 is attached is inserted into the cylinder bore 2 to measure roundness and the like. The measured data is sent to the computer 100, where calculation processing is executed, and roundness and cylindricity are obtained. As a result, it is possible to reproduce the state when the engine is operating in the assembled state of the engine, and to measure the roundness reflecting the influence of internal stress or thermal expansion accompanying the fastening of the cylinder head or the high temperature of the cooling water. it can.
Japanese Patent Laid-Open No. 7-270153 JP 2006-275760 A

  In the method for measuring the roundness of the cylinder bore, etc. developed by the present applicant, the cylinder block and the cylinder head are assembled with fastening bolts to form an assembly, and the roundness is measured in the assembled state. Roundness data that directly reflects the deformation of the cylinder bore can be obtained. In the case of a water-cooled engine, it is possible to measure the roundness in a state that approximates the operating state of the engine by circulating a high-temperature fluid in the water jacket.

  The cylinder head is a member that has a great influence on the roundness of the cylinder bore because it is firmly fastened to the cylinder block by the fastening bolt. However, in an actual engine, a bearing cap member having a semicircular concave portion facing the semicircular concave portion of the main bearing portion below the cylinder block is also fastened by a bolt (cap bolt). The journal portion of the crankshaft is supported between both semicircular recesses. In order to increase the rigidity of the crankshaft support, there is also an engine in which a plurality of Alling cap members are integrally connected and a ladder-like ladder frame in a plan view is fastened to the lower side of the cylinder block. Since such a bearing cap member is fastened to the cylinder block at a position relatively close to the cylinder bore, the roundness of the cylinder bore may change due to the fastening.

The measuring device such as roundness used in the measuring method developed by the present applicant is placed in the semicircular recess of the main bearing portion of the cylinder block and matches the semicircular recess of the adjacent main bearing portion. It is positioned by the reference member. Therefore, when the bearing cap member is fastened to the main bearing portion of the cylinder block, the measuring device cannot be placed in the semicircular recess of the cylinder block, and the roundness of the cylinder bore is fastened with the bearing cap member fastened. It is impossible to measure etc.
In measuring the roundness or cylindricity of the cylinder bore, the present invention measures not only the cylinder head but also the bearing cap member in the cylinder block, and obtains roundness measurement data that is more approximate to the engine operating state. This is the issue.

In view of the above problems, in the roundness measurement method of the present invention, the cylinder head is fastened to the cylinder block and the bearing cap member is fastened to the opposite side thereof. Install it on the table so that it is located above. Then, the placement block is installed over a plurality of semicircular recesses formed in the cylinder block, and a measuring device is placed on the placement block to measure the roundness of the cylinder bore. Is what you do. That is, the present invention
“A measuring method for measuring the roundness of a cylinder bore formed in a cylinder block of an engine by a measuring device having a measuring sensor supported rotatably and reciprocally,
The cylinder block includes a plurality of semicircular recesses forming one of the main bearing portions on one side thereof,
A plurality of bearing cap members each provided with a semicircular recess that forms the other of the main bearing portions are fastened to one side of the cylinder block, and a cylinder head is fastened to the other side of the cylinder block. A three-dimensional structure, and the cylinder assembly is installed on a table such that the bearing cap member is positioned above;
The mounting block is installed over the adjacent semicircular recess formed in the lower part of the cylinder block, and the measuring device is mounted on the mounting block. The sensor is inserted into the cylinder bore from above the cylinder assembly and the roundness is measured. "
It is a measuring method characterized by this.

  As described in claim 2, when the cylinder block and the cylinder head have a water jacket, a high-temperature fluid can be fed into the water jacket for measurement.

  As described in claim 3, the mounting block used in the measuring method of the present invention matches the semicircular recess formed on one side of the cylinder block on the lower surface of both ends thereof. It is preferable to use a mounting block in which a reference surface to be formed is formed and a through hole through which the measurement sensor passes is formed in the center. According to a fourth aspect of the present invention, it is preferable that a recess for positioning the measuring device is formed on the upper surface of the mounting block.

  And, as a measuring device used in the measuring method of the present invention, as described in claim 5, the measurement sensor inserted into the cylinder bore is rotated along the inner peripheral surface of the cylinder bore and A drive mechanism that reciprocates in the axial direction of the cylinder bore; and a base that holds the drive mechanism; and a reference member that has a reference surface that matches the inner peripheral surface of the cylinder bore is formed on the base. “Attached measuring device” is preferred. In this case, as described in claim 6, the drive mechanism is set as “a spline shaft into which the ball spline mechanism with the measurement sensor attached is fitted, and the ball spline mechanism in the axial direction of the cylinder bore by a feed screw mechanism. And an operation shaft for reciprocal movement.

  In the measuring method of the present invention, a plurality of bearing cap members (bearings) having a semicircular recess that forms the other of the main bearing portion on one side of the cylinder block in which the semicircular recess of the main bearing portion is formed. The cylinder assembly is constructed by fastening the cylinder head to the other side of the cylinder block, and the cylinder assembly is placed on the stand so that the bearing cap member is on the upper side as opposed to when the engine is operating. Install in. As a result, the lower surface of the cylinder block where the main bearing portion is present is exposed to the upper side, and the cylinder bore can be seen under the middle of the adjacent bearing cap member, and the axial direction of the crankshaft is between the bearing cap members. There is a certain space extending in a perpendicular direction. This situation does not change even when a ladder frame that integrally connects the bearing cap portions is attached.

Then, the placing block is placed over the adjacent semicircular concave portion of the main bearing portion formed in the cylinder block, and the measuring device is placed thereon. The mounting block has dimensions that can be installed in a semicircular recess in the main bearing portion, and can be inserted into the main bearing portion from the axial direction of the crankshaft even after the bearing cap member is fastened. However, depending on the case, before the bearing cap member is fastened, it may be preliminarily hung on the adjacent semicircular concave portion of the cylinder block.
The measuring device itself mounted on the mounting block is configured to be small so as to fit in a space extending between the bearing cap members in a direction perpendicular to the axial direction of the crankshaft. The measurement device is mounted with a measurement sensor that is rotatably and reciprocally supported. By inserting the measurement sensor into the cylinder bore from above, the cylinder head and the bearing cap member are fastened to the cylinder block. Roundness can be measured. Therefore, roundness data that directly reflects the deformation of the cylinder bore accompanying not only the cylinder head but also the tightening of the bearing cap member can be obtained, and the roundness in accordance with the actual state of the engine can be known.

  During operation of the water-cooled engine, cooling water circulates in the water jacket inside the cylinder block and the cylinder head, and the temperature of the cooling water rises due to high-temperature combustion gas. As in the second aspect of the invention, when a high temperature fluid is fed into both water jackets and measured, the state at the time of operation of the engine is approximately reproduced and affected by thermal expansion and the like. The roundness in the cylinder bore can be measured. For this reason, the measurement result is more similar to the roundness when the engine is operated.

  As the mounting block used in the measuring method of the present invention and spanning the adjacent semicircular recesses of the cylinder block, the lower surfaces of both ends of the mounting block, that is, the cylinder, as in the invention according to claim 3 When a reference surface that matches the concave portion is formed on the surface that contacts the semicircular concave portion of the block, and a through-hole through which the measuring sensor of the measuring device passes is formed at the center of the mounting block The mounting block can be easily positioned with respect to the semicircular recess of the cylinder block, and the measurement sensor can be easily inserted into the cylinder bore. Particularly, when a recess for positioning the measuring device is formed on the top surface of the mounting block as in the invention of claim 4, it becomes easy to accurately position the measuring device with respect to the mounting block.

  Further, as the measuring apparatus used in the measuring method of the present invention, the measuring apparatus of the invention of claim 5 is particularly suitable. That is, in the invention of claim 5, the reference member in which the reference surface that matches the inner peripheral surface of the cylinder bore is formed on the base that holds the drive mechanism that rotates and reciprocates the measuring sensor along the inner peripheral surface of the cylinder bore. Is installed. In the measuring method of the present invention, the cylinder assembly is installed with the bearing cap member facing upward, and the measuring device is placed on the upper surface of the mounting block and has a cylinder bore below it. Therefore, when the measuring device is placed with the reference surface in contact with the inner peripheral surface of the cylinder bore, the measurement sensor can be accurately positioned with respect to the cylinder bore. And since such positioning work only adjusts the reference plane, the operator can perform it manually in a short time and does not place an excessive burden on the operator. For example, even when a measuring device is installed in a cylinder assembly in which a high-temperature fluid is circulated through a water jacket, the work performed under a high-temperature environment can be completed in a short time.

  The drive mechanism in the roundness measuring device needs to have a function of rotating the measurement sensor along the inner peripheral surface of the cylinder bore and a function of moving the sensor up and down in the axial direction. In the measuring apparatus to be used, the drive mechanism must be accommodated in a space extending in a direction perpendicular to the axial direction of the crankshaft between the adjacent bearing cap members. As in the invention of claim 6, when the measuring sensor attached to the ball spline mechanism is reciprocated in the axial direction of the cylinder bore by the feed screw mechanism, the mechanism for moving up and down becomes small and can be stored in the above space. Thus, it becomes easy to make the whole measuring apparatus compact.

Hereinafter, a roundness measuring method and measuring apparatus for an engine cylinder bore according to the present invention will be described with reference to the drawings. In the drawings described below, the same reference numerals are given to components corresponding to the components of FIG. 9 described as the prior art.
First, the structure around the cylinder block in the water-cooled in-line engine will be described schematically with reference to FIGS. FIG. 1 is a longitudinal sectional view of an engine in which a cylinder head and a bearing cap member are assembled to a cylinder block, and FIG. 2 is an AA arrow view of the cylinder block fastened with the bearing cap member as viewed from below. ing. FIG. 3 shows a cross-sectional view of the cylinder block of the engine with the ladder frame assembled and a view of the ladder frame as viewed from below.

  In FIG. 1, a cylinder head 3 that closes a cylinder bore 2 is placed above a cylinder block 1 via a head gasket, and an intake / exhaust passage and an intake / exhaust valve are disposed in the cylinder head 3. The cylinder head 3 and the cylinder block 1 are firmly fastened by a long fastening bolt 4 so as to withstand the pressure of the combustion gas. A water jacket 5 through which cooling water flows is provided around the cylinder bore 2. The cooling water flows from the water jacket 5 into the water jacket 6 of the cylinder head 3, cools the cylinder block 1 and the cylinder head 3, and then It is discharged to the radiator.

  In order to attach a crankshaft (not shown) to the lower part of the cylinder block 1, a plurality of main bearing portions 7 corresponding to the number of crank journal portions of the crankshaft are formed. The main bearing portion 7 of the cylinder block 1 is a concave portion 71 having a semicircular cross section, and a bearing cap member 8 that similarly forms a semicircular bearing surface 81 is fixed by a cap bolt 82, and the crank journal portion is sandwiched between them. Attach the crankshaft to the lower part of the cylinder block 1. Therefore, as shown in FIG. 2, the main bearing portion 7 and the bearing cap member 8 are disposed on both sides of each cylinder bore 2. When viewed from below, a space S extending in a direction perpendicular to the crankshaft axis is formed between the bearing cap members 8, and the cylinder bore 2 can be seen through the space S. This situation is the same in the engine including the ladder frame 1R shown in FIG. 3, and there is a space S between the bearing cap members 8 that are integrally connected.

  The overall configuration of the method for measuring the roundness of the engine cylinder bore of the present invention is shown in FIG. In FIG. 4, a cylinder assembly 9 of a water-cooled engine, which is an object to be measured, is placed on the left side. This is the same as the engine of FIG. The bearing cap member 8 is fastened with a cap bolt 82 and attached with a bolt 4. The cylinder assembly 9 is installed on the base 10 in a direction opposite to the posture when the engine is operated, that is, the cylinder head 3 is located on the lower side and the bearing cap member 8 is located on the upper side, and the oil pan is attached. The lower surface of the cylinder block 1 and the bearing cap member 8 are exposed upward. Short pipes 11 and 12 serving as cooling water inlets and outlets are provided at the front part of the cylinder head 3 and the side part of the cylinder block 1 and communicate with the water jackets 6 and 5, respectively.

  The measurement method of this embodiment has the same configuration as the conventional measurement method shown in FIG. 9, and high-temperature water exceeding 100 ° C. is fed from the short tube 11 at the front of the cylinder head 3 by the pump 13. A high temperature oil tank 14 is provided to raise the temperature of the water. Here, silicon oil heated to about 130 ° C. by the electric heater 15 is stored, and the temperature of the water supplied to the pump 13 is increased by heat transfer. The high-temperature water fed from the front of the cylinder head 3 passes through the water jackets 6 and 5 of the cylinder head and the cylinder block, raises the temperature of the cylinder assembly 9, and then the short pipe 12 on the side of the cylinder block 1. And is returned to the high temperature oil tank 14. A flow rate adjusting valve 16 is provided on the discharge side of the pump 13, and the opening degree of the flow rate adjusting valve 16 is adjusted so that the temperatures on the supply side and the discharge side detected by the temperature detectors 17 and 18 become appropriate values. The 19 is a pressure gauge which detects the pressure of high temperature water.

After such preparation, the measuring device 20 of the present invention represented by a two-dot chain line is installed between the bearing cap member 8 on the upper surface of the cylinder assembly 9, that is, the lower surface of the cylinder block 1. Although the measuring device 20 will be described in detail later, the measuring device 20 is configured to be small so as to be accommodated in the space S (FIG. 2) between the adjacent bearing cap members 8, and is used for mounting the measuring device 20. The mounting block 21 is spanned in advance in a semicircular recess 71 adjacent to the main bearing portion of the cylinder block 1. A reference member 22 having two reference surfaces is attached to the measuring device 20, and the reference surfaces abut on the inner peripheral surface of the cylinder bore 2. Thereby, the spline shaft 29 provided with the measuring device 20 and the measuring sensor 24 is stably held at a predetermined position, and the roundness is measured. The measured data is input to the computer 100, and arithmetic processing is performed to obtain roundness and cylindricity.
The cylinder head 3 and the bearing cap member 8 are firmly fixed to the cylinder block 1 in which the cylinder bore 2 is formed by fastening bolts 4 and the like, as in the case of engine operation. In this state, an internal stress is generated around the cylinder bore due to the bolt tightening, and the roundness measurement result reflects the influence of the stress.

  In addition, since the high temperature water is passed through the water jacket 5 of the cylinder block 1 and the temperature around the cylinder bore is raised, the measurement result of roundness takes into account the effects of thermal expansion and thermal stress. Further, it is possible to obtain a measurement result approximated when the engine is operating. In this embodiment, high-temperature water heat-exchanged with silicon oil is pressurized to about 0.15 MP and circulated through the cylinder assembly 9, but in some cases, silicon oil may be directly fed, High temperature steam may be supplied instead of water and high temperature oil.

Next, the measuring apparatus 20 of the present invention will be described with reference to FIGS.
As shown in FIG. 5, the measuring apparatus 20 of the present invention includes a base 23, and the base 23 rotates a measurement sensor 24 along the inner week surface of the cylinder bore 2, and the axial direction of the cylinder bore 2. A drive mechanism 25 for reciprocating is mounted. Below the central portion of the base 23, there are provided bearing boss portions 23A in which both side surfaces in the longitudinal direction are formed in parallel. At both ends of the base 23, an operator holds the measuring device 20 and sets a cylinder assembly. A handle 27 for installation on a solid body is fixed.

  A spline shaft 29 that extends downward and a feed screw shaft 30 that moves in the vertical direction are disposed in the central portion of the measuring device 20. The spline shaft 29 is fitted with a spline sleeve 32 that is integrally connected to the attachment member 31 of the measurement sensor 24. A spline groove is formed in the spline shaft 29 in a straight line in the vertical direction, and the spline sleeve 32 is rotated in the housing 34 so as to rotate together with the spline shaft 29 by a ball fitted between the spline groove and the groove of the spline sleeve. Mounted through bearings. These constitute a ball spline mechanism. The housing 34 is fixed to the lower end of the feed screw shaft 30, and the spline sleeve 32 and the measuring sensor 24 connected integrally therewith are connected to the spline shaft. The spline shaft 29 can be slid in the axial direction while rotating by the rotation of 29.

  The spline shaft 29 is pivotally supported on the base 23 by a bearing disposed in the bearing boss portion 23A. A spline shaft drive motor 35 for rotating the spline shaft 29 is installed on the base 23, and the rotation of the spline shaft drive motor 35 is transmitted to the spline shaft 29 via a round belt 36. Such a driving mechanism of the measurement sensor 24 is basically the same as that shown in Patent Document 2.

  However, a feed screw shaft 30 is adopted as an operation shaft for moving the measurement sensor 24 in the vertical direction instead of the rack and pinion type operation shaft, and the feed screw shaft 30 rotates the vertical movement nut 37. To move up and down. A hollow stepping motor 38 that rotates the vertically moving nut 37 is installed on the base 23, and the feed screw shaft 30 is disposed so as to penetrate the hollow portion. As a result, the vertical drive device of the measurement sensor 24 can be configured compactly, and the measurement device 20 is also small. Rotary encoders 39 and 40 for detecting the rotation angle are respectively attached to the rotation shafts of the spline shaft drive motor 35 and the vertical movement nut 37, and the rotary position of the measurement sensor 24 is detected by the rotary encoder 39. , The axial position is detected, and these detection signals are sent to the computer 100 (FIG. 4).

  A reference member 22 having two reference surfaces is fixed to the bearing boss portion 23A below the base 23 with screws. As is apparent from FIG. 6, the reference member 22 is a member in which two arc-shaped reference surfaces 22A and 22B that match the cylinder bore 2 are connected by a central plate 22C, and a spline shaft 29 is provided on the central plate 22C. A through-hole through which the feed screw shaft 30 passes and two screw holes for mounting screws are provided. The two reference surfaces 22A and 22B of this embodiment have different arc lengths, but may be configured to have arc portions of the same length. The reference member 22 functions as a guide member when the measurement device 20 is installed on the cylinder assembly 9, and the measurement sensor 24 is brought into contact with the inner peripheral surface of the cylinder bore 2 by contacting the reference surfaces 22 </ b> A and 22 </ b> B. The spline shaft 29 to which is attached can be accurately arranged along the center axis of the cylinder bore 2. In order to enable measurement of the roundness of various engines, a plurality of reference members 22 corresponding to the dimensions of the cylinder bore and the like are prepared, and are exchanged depending on the engine to be measured.

Here, the mounting block 21 used when installing the measuring apparatus 20 on the cylinder assembly 9 will be described. The mounting block 21 spans the semicircular recess 71 of the main bearing portion of the cylinder block 1 for mounting the measuring device 20, and FIG. 7 shows the structure of the mounting block 21 itself in FIG. Shows the state when it is passed over the main bearing portion 7.
As shown in FIG. 7, the mounting block 21 is formed in the semicircular recess 71 of the main bearing portion of the cylinder block 1 so that the lower surface 21 </ b> B of both end portions 21 </ b> A serves as a reference surface when installed on the main bearing portion. Matching semicircular shape, the upper surface is flat. As can be seen from the side view, the mounting block 21 has a shape in which one side is cut off with respect to the central axis (the axis passing through the axis of the main bearing portion), and is therefore asymmetric with respect to the central axis. The dimension X is longer than the dimension Y. In order to place the measuring device 20 at the center of the mounting block 21, a recess 21D having a substantially rectangular cross section provided with both parallel walls 21C is provided. Further, a housing 34 attached to the spline shaft 29 of the measuring device 20 and a through hole 21E through which the measuring sensor 24 passes are formed below the recess 21D.

  As shown in FIG. 8, the mounting block 21 is installed across the adjacent semicircular concave portions of the main bearing portion 7 of the cylinder block 1. At this time, the lower surface 21B matches the semicircular recess of the main bearing portion of the cylinder block 1, and the center shaft 21O of the mounting block 21 is placed at the position of the axis of the main bearing portion, and the circular portion of the through hole 21E. Is coincident with the center axis of the cylinder bore 2. The mounting block 21 can be inserted into the main bearing portion from the axial direction of the crankshaft and spanned to an appropriate position even after the bearing cap member 8 is assembled to the cylinder block 1, but before the bearing cap member 8 is assembled. In addition, the mounting block 21 may be installed in advance on the adjacent main bearing portion.

  As shown by a two-dot chain line in FIG. 8, the measuring device 20 is in such a posture that its longitudinal direction is orthogonal to the axial direction of the crankshaft, and the lower surface of the reference member 22 is the bottom plane of the recess 21 </ b> D of the mounting block 21. Is placed on the placement block 21 (see FIG. 5). At this time, the spline shaft 29 attached with the measurement sensor 24 and the like is inserted into the lower cylinder bore 2 through the through-hole 21E, and the reference surfaces 22A and 22B of the reference member 22 are located on both sides of the mounting block 21. And reaches the inner peripheral surface of the cylinder bore 2 and abuts the cylinder bore 2 to accurately position the measuring device 20 and the spline shaft 29. Therefore, the reference member 22 of the measuring apparatus 20 is attached so that the reference surface 22A having a long arc portion is on the side where the mounting block 21 is cut off, that is, on the dimension Y side. Further, both parallel side surfaces of the bearing boss portion 23 </ b> A of the measuring device 20 are fitted between both parallel walls of the recess 21 </ b> D of the mounting block 21, so that the mounting block 21 is accurate with respect to the cylinder bore 2. Positioning will be performed.

Next, how the measuring apparatus 20 is used in connection with the measuring method of the present invention will be described.
As described with reference to FIG. 1, when measuring the roundness of the cylinder bore 2, the cylinder head 3 is fastened to the cylinder block 1 of the engine, and the bearing cap member 8 is fastened by the cap bolt 82. Then, the cylinder assembly 9 is installed on a table with the bearing cap member 8 facing upward, and the mounting block 21 is spanned between the main bearing portions 7. After such preparation, the cylinder assembly 9 is supplied with hot fluid by the pump 13. When a predetermined time has elapsed and the temperature difference between the inlet and outlet of the fluid and the temperature of the cylinder block 1 are stabilized, the operator holds the handle 27 of the measuring device 20 of the present invention by hand and places the bearing cap member 8 between them. It is mounted on the mounting block 21 from above.

  The measuring device 20 is configured to be small so that it can be accommodated in a space between the bearing caps in the cylinder block. A reference member 22 for positioning a spline shaft 29 in which a measurement sensor 24 is fitted is attached below the measuring device 20, and the mounting block 21 matches the semicircular recess of the main bearing portion 7. The lower surface 21 </ b> B and the central recess 21 </ b> D into which the bearing boss portion of the measuring device 20 is fitted are formed. Therefore, the setting operation of the measuring device performed by the operator is easy and can be performed in a short time, and an excessive burden is placed on the operator even in a situation where the cylinder block 1 is at a high temperature and the working environment is deteriorated. There is nothing.

  After the measuring device 20 is set on the assembly 9, the roundness is measured by controlling the drive mechanism 25 of the measuring sensor 24 by a control device such as a computer connected thereto. Specifically, the feed screw shaft drive motor 38 is rotated to set the measurement sensor 24 at a predetermined position in the axial direction of the cylinder bore 2, and the spline shaft drive motor 35 is rotated to rotate the measurement sensor 24 to the center of the cylinder bore 2. The roundness is obtained by continuously measuring the distance between the shaft and the inner peripheral surface. By processing data obtained by performing roundness measurement at a number of positions in the axial direction, the distribution of roundness in the axial direction, that is, the cylindricity of the cylinder bore 2 is obtained. As the measurement sensor 24, for example, a well-known sensor such as a capacitance sensor or an eddy current sensor is appropriately selected and used in consideration of the material of the cylinder block 1 and the like.

  As described above in detail, the roundness measuring method of the cylinder bore according to the present invention measures the roundness in the actual engine operating state in which the bearing cap is fastened to the cylinder block together with the cylinder head with the fastening bolt. Furthermore, measurement is performed by passing a high-temperature fluid through the water jacket. In the above-described embodiment, an in-line engine is described. However, it is clear that the roundness measuring method of the present invention can be applied to, for example, a V-type engine as long as the cylinder bore can be seen from the lower surface of the cylinder block. It is. Needless to say, the present invention can be applied not only to an engine in which a plurality of bearing cap members are independently fixed, but also to an engine provided with a ladder frame.

It is sectional drawing which shows the structure of a water-cooled engine. It is an AA arrow line view of FIG. 1 which shows a cylinder block lower surface. It is a figure of the engine which has a ladder frame. It is a general view which shows the measuring method of the engine cylinder bore roundness of this invention. 1 is an overall view of a roundness measuring apparatus of the present invention. It is a figure of the reference member in the measuring device of the present invention. It is a figure of the mounting block of this invention. It is a figure which shows the state which spanned the mounting block of this invention to the main bearing part. It is a figure which shows the conventional roundness measuring method and measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder bore 3 Cylinder head 4 Fastening bolt 7 Main bearing part 8 Bearing cap member 82 Cap bolt 9 Cylinder assembly 20 Measuring apparatus 21 Mounting block 22 Reference member 23 Base 24 Measuring sensor 25 Drive mechanism 29 Spline shaft 30 Lead screw shaft (operation shaft)
32, 34 Ball spline mechanism 35 Spline shaft rotation drive motor 38 Feed screw shaft drive motor 39, 40 Rotary encoder

Claims (6)

A measurement method for measuring the roundness of a cylinder bore formed in a cylinder block of an engine by a measurement device including a measurement sensor that is supported rotatably and reciprocally,
The cylinder block includes a plurality of semicircular recesses forming one of the main bearing portions on one side thereof,
A plurality of bearing cap members each provided with a semicircular recess that forms the other of the main bearing portions are fastened to one side of the cylinder block, and a cylinder head is fastened to the other side of the cylinder block. A three-dimensional structure, and the cylinder assembly is installed on a table such that the bearing cap member is positioned above;
The mounting block is installed over the adjacent semicircular recess formed in the lower part of the cylinder block, and the measuring device is mounted on the mounting block. A roundness is measured by inserting a sensor for use into the cylinder bore from above the cylinder assembly.   The measurement method according to claim 1, wherein the cylinder block and the cylinder head have a water jacket, and a hot fluid is fed into the water jacket for measurement.   3. The mounting block used in the measuring method according to claim 1 or 2, wherein the lower surface of both end portions matches the semicircular recess formed on one side of the cylinder block. A mounting block in which a reference surface is formed and a through-hole through which the measurement sensor passes is formed in the center.   The mounting block according to claim 3, wherein a recess for positioning the measuring device is formed on an upper surface. A measuring apparatus used in the measuring method according to claim 1 or 2,
The measuring device includes a driving mechanism that rotates a measuring sensor inserted into the cylinder bore along the inner peripheral surface of the cylinder bore and reciprocates in the axial direction of the cylinder bore, and a base that holds the driving mechanism. In addition,
A measuring device in which a reference member that forms a reference surface that matches the inner peripheral surface of the cylinder bore is attached to the base.   The drive mechanism includes a spline shaft into which a ball spline mechanism to which the measurement sensor is attached is fitted, and an operation shaft that reciprocates the ball spline mechanism in the axial direction of the cylinder bore by a feed screw mechanism. Item 6. The measuring device according to Item 5.

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