Claims:We claim:

1. A system for calibration and measurement of the center-to-center distance between two mutually perpendicular bores, a first bore (B1) involving a blind hole and a second bore (B2), both bores (B1, B2) machined in an automotive component (C) having complex and inaccessible profile, said system comprising:

• a setting master (160) with a partial hole (B11) to simulate said first bore (B1), and a through hole (B12) to simulate said second bore (B2); and

• said measuring instrument (100) configured for accurately and reliably measuring the center-to-center distance (D) between bores (B1, B2);

wherein said setting master (160) is configured with the same profiles and dimensions, like lengths (L1, L2), diameters (B1, B2), angle (a) and axial distance (D) as in said component (C) to accurately measure the center-to-center distance (D) between said bores (B1 and B2), said partial hole (B11) accommodates measuring instrument (100) therein and said through hole (B12) is inserted with a mandrel (170) for precise calibration of measuring instrument (100) to zero reading thereof.

2. System for calibration and measurement as claimed in claim 1, wherein said partial hole (B11) is a partial hole (162) which simulates the axial position of the first bore (B1) and accommodates the lower end of measuring instrument (100) therein and through hole (B12) is a through hole (164) which accommodates the outer diameter (172) of mandrel (170) therein and simulates the axial position of second bore (B2); whereby measuring instrument (100) accurately and reliably measures the center-to-center distance (D) between said bores (B1 and B2).

3. System for calibration and measurement as claimed in claim 2, wherein said hole (164) is configured in an extension (166) of setting master (160), the axis of which is perpendicular to and directed away from the axis of said hole (162) at an angle (a).

4. System for calibration and measurement as claimed in claim 3, wherein said setting master (160) comprises said partial hole (162) equal to the oil pump bore (BOP), and said through hole (164) equal to the camshaft bore (BC), said bores (BOP, BC) machined in a crankcase assembly (200) of an internal combustion engine.

5. System for calibration and measurement as claimed in claim 4, wherein axis of said hole (162) functions as oil pump bore (BOP) axis when measuring instrument (100) is supported therein, and said hole (164) functions as camshaft bore (BC) axis when mandrel (170) is inserted therein for simulating the center-to-center distance (D) between bores (BOP, BC) by calibrating measuring instrument (100) to a zero reading before actual measurement of said center-to-center distance (D).

6. System for calibration and measurement as claimed in claim 1, wherein said measuring instrument (100) comprises:

• a dial indicator (110);

• a bracket assembly (120) for securely holding dial indicator (110);

• a body assembly (130) having a body (132) with a cavity (134) for accommodating a profiled fulcrum lever (136) pivotable therein and a counterbore hole (135) connected thereto;

• a gauge pin (138) with the lower end thereof inserted from top of body assembly (130) into a through hole (131) provided therein for making contact with fulcrum lever (136), and the upper end thereof in contact with dial indicator (110);

• a cover (140) to protect body assembly (130) from contaminations; and

• a bush assembly (150) accommodated inside counterbore hole (135) for contacting fulcrum lever (136);

wherein said bush assembly (150) is in contact with bore (B2) of machined component (C) when measuring instrument (100) is accurately positioned inside bore (B1) and bush assembly (140) thereof contacts bore (B2) precisely perpendicular to the axis of bore (B1) for accurately and reliably measuring center-to-center distance (D) between bores (B1, B2) and for displaying said distance (D) on dial indicator (110).

7. System for calibration and measurement as claimed in claim 6, said bracket assembly (120) comprises:

• a bracket (104) for holding dial indicator (110) by means of a fastener (107);

• a pair of guide plates (122, 124) fastened on body assembly (130) by means of a locking pin (126);

• a top plate (125) fastened on top of guide plates (122, 124), said top plate (125) having an aperture for fixing fasteners (116, 118) therethrough;

wherein said fasteners (116, 118) are used for adjusting the vertical height of bush assembly (150) with respect to machined component (C) and depending on the targeted center-to-center distance (D) between bores (B1, B2) by using measuring instrument (100).

8. System for calibration and measurement as claimed in claim 6, said body assembly (130) comprises:

• a body (132) with through hole (131) made therein for inserting gauge pin (138) therethrough;

• body (132) provided with flat surfaces (133, 137) with holes for fastening bracket (104) and guide plates (122, 124) thereon;

• body (132) provided with a counterbore hole (135) connected to cavity (134) for accommodating bush assembly (150);

• fulcrum lever (136) with a pivot portion to pivot about a dowel pin (109) fitted in body (132) disposed perpendicular to gauge pin (138) axis;

wherein said fulcrum lever (136) is configured with a limb extending perpendicular to said pivot portion, one end of limb in contact with lower end of gauge pin (138) and the other end thereof in contact with bush assembly (150).

9. System for calibration and measurement as claimed in claim 6, said cover (140) comprises a cup-like hollow body with the hollow open portion thereof fitted over the thick lower end of body (132), said hollow body enclosing said cavity (134); cover (140) having a minor depression (141) with a hole aligned with the center of counterbore hole (135) provided in mini bush (142):

10. System for calibration and measurement as claimed in claim 6, said bush assembly (150) comprises:

• a mini bush (142) having a flanged head to be supported in counterbore hole (135) and the base of mini bush (142) projecting into cavity (134) to connect a hollow space (143) of mini bush (142) to cavity (134);

• a pin-like mini plunger (144) slidable within hollow space (143) and having a pointed tip head disposed at the center of minor depression (141), said pointed tip head slidable through a hole provided in minor depression (141), the other end of mini plunger (144) projecting into cavity (134), said other end having a groove (147) formed therein;

• a compression spring (146) placed over mini plunger (144) between said pointed-tip head and the bottom side of hollow space (143), spring (146) applying pressure on mini plunger (144) for protruding said pointed-tip head thereof out of cover (140) to contact the surface of mandrel (170) disposed inside bore (B2); and

• a circlip (148) placed in groove (147) of mini plunger (144) after assembly of mini plunger (144) with spring (146) pressed between the base of mini bush (142) and said pointed tip head of mini plunger (144) for holding of bush assembly (150) intact;

wherein the thickness of counterbore hole (135) is configured depending on the targeted center-to-center distance (D) to be measured between machined bores (BOP, BC) of said component (C).

11. System for calibration and measurement as claimed in claim 8, said fulcrum lever (136) comprises a T-shaped profile with the web thereof pivotable about dowel pin (109), fulcrum lever (136) having a flange with one end thereof in contact with the lower end of gauge pin (138) and the other end thereof in contact with the thin end of mini plunger (144) after assembly thereof in body assembly (130).

12. System for calibration and measurement as claimed in claim 7, wherein a grub screw (112) each is provided on outer faces of plates (122, 124) for centering of measuring instrument (100) about gauge pin (138).

13. System for calibration and measurement as claimed in claims 7 and 8, wherein a grub screw (108) is provided on the upper portion of body (132) and disposed above and perpendicular to locking pin (126) for preventing rotation of gauge pin (138) about the axis thereof and to lock gauge pin (138) in body (132).

14. System for calibration and measurement as claimed in claim 6, wherein a longitudinal slot (139) is provided on gauge pin (138) for facilitating the inspection and operation of measuring instrument (100).

15. System for calibration and measurement as claimed in claim 10, wherein said measuring instrument (100) is configured to measure the center-to-center distance (D) to be measured between machined bores (BOP, BC) of component (C), said distance is in the range of 50-80 microns.

16. A method of measurement conducted by the system for calibration and measurement as claimed in claims 1-15, said method comprising the steps of:

(a) inserting mandrel (170) in through hole (B12) of setting master (160);

(b) placing measuring instrument (100) with the lower end thereof disposed in partial hole (B11) of setting master (160);

(c) adjusting the vertical height of bush assembly (150) with respect to mandrel (170) by means of fasteners (116, 118);

(d) calibrating and pre-setting the dial indicator (110) for pre-setting measuring instrument (100) to zero reading on the tip of mini plunger (144) contacting the outer diameter of mandrel (170) placed in through hole (B12);

(e) removing mandrel (170) and measuring instrument (100) from setting master (160);

(f) inserting mandrel (170) in second bore (B2) of machined component (C);

(g) inserting the lower end of pre-set measuring instrument (100) in first bore (B1) of machined component (C);

(h) rotating fastener (116) in top plate (125) of bracket assembly (120) until fastener (116) head rests on bearing cap (180) of crankshaft;

(i) reading the deviation of dial indicator (110) from preset zero reading thereof; and

(j) calculating the distance (D) between said bores (B1, B2) by computing the difference of deviation of dial indicator (110) reading from preset zero reading thereof.

17. Method as claimed in claim 16, wherein said method comprises accurately, reliably and quickly measuring the center-to-center distance (D) between oil pump bore (BOP) and camshaft bore (BC) machined in an automotive component (C) having complex and inaccessible profile.

Dated this 24th day of July 2019.

Digitally Signed.

(SANJAY KESHARWANI)
REGN. NO. IN/PA-2043.
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention concerns a calibration and measurement system for measuring distances between bores involving blind holes machined in components having intricate profiles. In particular, the present invention relates to an system for measuring distances between bores involving blind holes machined in crankcases. More particularly, the present invention relates to an system for accurately and reliably measuring distances between oil-pump bore and camshaft bore machined during crankcase machining without using coordinate measuring machine (CMM).

BACKGROUND OF THE INVENTION

While performing boring operations in automotive manufacturing process, some bore-to-bore distances are very critical for interoperability of complex components, particularly components having blind holes.

An exemplary case being crankcase machining, in which oil-pump bore and camshaft bore is of a very critical nature. Normally, Medium Dependent Interface (MDI) is used for complex oil-pump boring operation during crankcase machining, in which the center distance (±0.064mm) between the oil pump bore and camshaft bore is very critical. Generally, manual checking is done based on operator’s judgement and experience. Presently, there is no instrument available for checking this center distance and this distance is checked by using attribute type of gauge. A skilled and experienced operator sets the cutter to achieve exact center distance between cam shaft bore and oil-pump bore.

Alternatively, CMM (coordinate measuring machine) inspection can be done for measuring this center distance between the oil pump bore and cam bore. However, even after CMM inspection, some correction is required for setting the cutter to achieve exact specified center distance.
Moreover, this coordinate measuring machine (CMM) inspection is necessary for cross-verification of this center distance. However, conducting this CMM inspection requires about 2 hours, which results in reducing the crankcase machining capacity.

PRIOR ART

CN108413835A, titled “Detecting device and method for distance between valve line of cylinder cover air valve and cam hole center” discloses a detecting device and method for distance between a valve line of a cylinder cover air valve and the cam hole center. The detecting device comprises a measuring device, a dial indicator, a calibrating device and a cam central spindle, the calibrating device is used for calibrating the measuring device, the cam central spindle is used for being installed inside the cam hole of the cylinder cover, the measuring device comprises a measuring column, the calibrating device comprises a calibrating meter seat vertically installed, and the dial indicator respectively detects the connection of a contact and top end of the measuring column; during the calibrating state, the measuring end of the measuring column is inserted into the calibrating seat for calibration, during the measuring state, and the measuring end of the measuring column is inserted into the valve line of the cylinder cover air valve and is in contact with the periphery side of the cam central spindle. The detecting device is mainly used for measuring the distance between the cylinder cover air valve and the cam hole center, is more targeted, and is convenient to move, during the detection, the cylinder cover is not needed to be moved, the detection is convenient, the detecting device can be applied to multiple working condition scenes and has the advantages that the whole structure is light, the manufacturing coat is low, the measuring accuracy is high, and the production efficiency can be improved.

CN201434660Y, titled “Detection device for detecting perpendicularity of axis and runout of end surface of hole” discloses a detection device for detecting the perpendicularity of the axis and the runout of the end surface of a hole, which aims to provide a detection device with the advantages of simple structure, less detection links, low cost, high detection efficiency, strong universality, and capability of detecting the perpendicularity of the axes and the runout of the end surface of a hole quickly and accurately. The device comprises a detection head rotating in a hole of a component to be detected and a dial test indicator for detecting circle run-out, as well as a detection pin (7) capable of extending the hole to be detected and a lever (1) axially connected with the detection pin (7); the lever (1) is vertically assembled in a regulation hole of a test indicator rack (2) and is parallel to the dial test indicator (4) mounted at the upper end of the test indicator rack (2); and a test indicator head can rotate on the detected surface of a component to be detected so as to record detection indicating values of a plurality of positions. The utility model solves the problems of hole drilling as well as the detection of perpendicularity and end surface run-out of non-rotary components and can be widely applied to the detection of various components.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an instrument for measuring distances between bores machined during crankcase machining.

Another object of the present invention is to provide an instrument for accurate measurement of the critical distances machined during crankcase machining.

Still another object of the present invention is to provide an instrument for accurate measurement of the center distance between oil-pump bore and camshaft bore machined during crankcase machining.

Yet another object of the present invention is to provide an instrument for accurate measurement of the center distance between oil-pump bore and camshaft bore machined in the crankcase without any CMM inspection.

A further object of the present invention is to provide a method for accurate and quick measurement of the center distance between oil-pump bore and camshaft bore machined during crankcase machining.

A still object of the present invention is to provide a simple method for accurate and quick measurement of the center distance between oil-pump bore and camshaft bore machined without requiring any CMM inspection personnel.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF INVENTION

In accordance with the present invention, there is provided a system for calibration and measurement of the center-to-center distance between a bore involving a blind hole and a through bore, both these bores machined in an automotive component having complex and inaccessible profile, the system comprising:

• a setting master with a first bore to simulate bore machined in the machined component and for positioning a measuring instrument therein, and a second bore to simulate the through bore machined in the component and for positioning a mandrel therein; and

• the measuring instrument for accurately and reliably measuring the center-to-center distance between these bores;

wherein the setting master is configured with the same profiles and dimensions, like lengths, diameters, angle and axial distance as in the component to accurately measure center-to-center distance between bores, the setting master having a first bore for accommodating measuring instrument therein and a second bore for inserting mandrel therein for precise calibration of measuring instrument to zero reading thereof.

Typically, the partial hole is the hole for simulating the axial position of bore of machined component and to accommodate the lower end of measuring instrument therein and the through hole is the hole for accommodating outer diameter of mandrel therein for simulating the axial position of bore of machined component, whereby measuring instrument accurately and reliably measures the center-to-center distance between these bores of machined component.

Typically, the partial hole is configured in an extension of setting master, the axis of which is perpendicular to and directed away from the axis of the through hole at an angle.

Typically, the setting master comprises the partial hole equal to the oil pump bore and the through hole equal to the camshaft bore, these bores are machined in a crankcase assembly of an internal combustion engine.

Typically, the axis of the partial hole of setting master functions as the oil pump bore axis when measuring instrument is supported therein, and the through hole of the setting master functions as the camshaft bore axis when mandrel is inserted therein for simulating the center-to-center distance between these bores by calibrating measuring instrument to zero reading before actual measurement of the distance.

Typically, the measuring instrument comprises:

• a dial indicator;

• a bracket assembly for securely holding the dial indicator;

• a body assembly having a body with a cavity for accommodating a profiled fulcrum lever pivotable therein and a lateral depression connected thereto;

• a gauge pin with the lower end thereof inserted from top of body assembly through hole provided therein for making contact with fulcrum lever, and the upper end thereof in contact with dial indicator;

• a cover to protect body assembly from contaminations; and

• a bush assembly accommodated inside the lateral depression for contacting fulcrum lever;

wherein the bush assembly is in contact with bore of machined component with measuring instrument accurately positioned inside bore and bush assembly thereof contacting bore precisely perpendicular to the axis of bore for accurately and reliably measuring the center-to-center distance between these bores and for displaying distance on dial indicator.

Typically, the bracket assembly comprises:

• a bracket for holding dial indicator by means of a fastener;

• a pair of guide plates fastened on body assembly by means of a locking pin;

• a top plate fastened on top of guide plates, top plate having an aperture for fixing fasteners therethrough;

wherein the fasteners are used for adjusting the vertical height of the bush assembly with respect to machined component and depending on the targeted center-to-center distance between bores by using measuring instrument.

Typically, the body assembly comprises:

• body having a through hole made therein for inserting gauge pin therethrough;

• body provided with flat surfaces with holes for fastening bracket and guide plates thereon;
• body provided with a lateral hole connected to cavity for accommodating bush assembly;

• fulcrum lever having a pivot portion to pivot about a dowel pin fitted in body disposed perpendicular to the gauge pin axis;

wherein the fulcrum lever is configured with a limb extending perpendicular to the pivot portion, one end of the limb is in contact with lower end of the gauge pin and the other end thereof in contact with bush assembly.

Typically, the cover comprises a cup-like hollow body with the hollow thereof fitted over the lower end of the hollow body, the hollow body enclosing the cavity; the cover having a minor depression aligned with the center of the counterbore hole provided in mini bush.

Typically, the bush assembly comprises:

• a mini bush having a flanged head to be supported in the lateral depression and an extension therefrom projecting into the cavity, the extension having a hollow space with a hole in the bottom thereof;

• a pin-like mini plunger slidable within the hollow space and having a pointed tip head disposed at the center of the lateral depression, the pointed tip head slidable through a hole provided in minor depression, the other end of mini plunger projecting into the cavity, the other end having a groove formed therein;
• a compression spring) placed over the plunger between the pointed-tip head and the bottom side of the hollow space, the spring applying pressure on mini plunger for protruding the pointed-tip head thereof out of cover to contact the surface of mandrel (170) disposed inside the bore;

• a circlip placed in the groove of mini plunger after assembly of the mini plunger with spring pressed between the base the mini bush and pointed tip head of mini plunger hole for holding of the bush assembly intact;
wherein the thickness of the lateral depression is configured depending on the targeted center-to-center distance to be measured between these machined bores of the component.

Typically, the fulcrum lever comprises a T-shaped profile with the web thereof pivotable about dowel pin, fulcrum lever (136) having a flange with one end thereof in contact with the lower end of the gauge pin and the other end thereof in contact with the mini plunger after assembly thereof in the body assembly.

Typically, a grub screw each is provided on outer faces of the plates for centering of measuring instrument about the gauge pin.

Typically, a grub screw is provided on the upper portion of body and disposed perpendicular to and above locking pin for preventing rotation of gauge pin about the axis thereof and to lock gauge pin in body of measuring instrument.

Typically, a longitudinal slot is provided on gauge pin for facilitating the inspection and operation of measuring instrument.

Typically, the measuring instrument is configured to measure the center-to-center distance to be measured between machined bores of the component, the distance is in the range as low as a few microns, preferably in a range of 50-80 microns.

In accordance with the present invention, there is also provided a method of measurement of distance between a bore involving a blind hole and another bore disposed at a distance therefrom, and machined in an automotive component having complex and inaccessible profile, the measurement conducted by the calibration and measurement system configured in accordance with the present invention, the method comprising the steps of:

(a) inserting mandrel in the through hole of the setting master;

(b) placing measuring instrument with the lower end thereof disposed in the partial hole of the setting master;

(c) adjusting the vertical height of bush assembly with respect to mandrel by means of fasteners;

(d) calibrating and pre-setting the dial indicator for pre-setting measuring instrument to zero reading on the mini plunger tip contacting the outer diameter of the mandrel placed in the second bore thereof;

(e) removing mandrel and measuring instrument from setting master; and

(f) inserting mandrel in first bore of the machined component;

(g) inserting the lower end of the pre-set measuring instrument in second bore of the machined component;

(h) rotating fastener in top plate of bracket assembly until fastener head rests on bearing cap of crankshaft;

(i) reading the deviation of dial meter from preset zero reading thereof; and

(j) calculating the distance between two bores by computing the difference of the deviation of dial indicator reading from the preset zero reading thereof.

Typically, the method comprises accurately, reliably and quickly measuring the center-to-center distance between oil pump bore and camshaft bore machined in an automotive component having complex and inaccessible profile.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described in the following with reference to the accompanying drawings.

Figure 1a shows a perspective view of the measuring instrument configured in accordance with the present invention for accurate and quick measurement of the center distance between oil-pump bore and camshaft bore machined during crankcase machining.

Figure 1b shows a front view of the measuring instrument configured in accordance with the present invention and shown in Figure 1a.

Figure 2 shows an exploded view of the measuring instrument configured in accordance with the present invention and shown in Figure 1a.

Figure 3a shows a perspective view of the bush assembly disposed at the lower end of measuring instrument 100 depicted in Figure 1a.

Figure 3b shows an exploded view of the bush assembly of Figure 3a.

Figure 4a shows a perspective view of the crankcase depicting the oil pump bore and camshaft bore machined therein for measurement of center to center distance therebetween.

Figure 4b shows a perspective view from top of the crankcase after positioning the measuring instrument supported on the mandrel of setting master and precisely aligned in the oil-pump bore according to the present invention.

Figure 4c shows a perspective view from side of the crankcase positioned with the measuring instrument of Figure 4b.

Figure 5a shows a cross-sectional view of the crankcase configured to precisely simulating the center-to-center distance between oil pump bore and camshaft bore in the crankcase of an internal combustion engine.

Figure 5b shows front, side and top views of a setting master configured to precisely simulating the center-to-center distance between oil pump bore and camshaft bore in the crankcase of an internal combustion engine.

Figure 5c shows front, side and top views of the setting master with the mandrel placed therein, but before positioning the measuring instrument.

Figure 5d shows front, side and top views of the setting master of Figure 5b with the mandrel placed therein and after positioning and supporting measuring instrument thereon.

Figures 6-6a-6d show detailed sectional views of the measuring instrument configured in accordance with the present invention and placed in the crankcase and held in place by the bearing cap of the crankshaft.

Figure 7a shows an enlarged view of the exploded lower end of the measuring instrument configured in accordance with the present invention.

Figure 7b shows an enlarged sectional view of the lower end of Figs. 6 and 7a.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the system for calibration and measurement of center-to-center distance between two mutually perpendicular bores in machined component, such an oil-pump bore and camshaft bore machined during crankcase machining and configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention.

Figure 1a shows a perspective view of the measuring instrument 100 configured in accordance with the present invention to accurately, reliably and quickly measuring the center-to-center distance between oil-pump bore and camshaft bore machined in crankcase. It includes dial indicator 110, bracket assembly 120, body assembly 130, cover 140 and bush assembly 150.

Figure 1b shows a front view of the measuring instrument 100 configured in accordance with the present invention and shown in Figure 1a and depicting dial indicator 110 contacting the upper end of guide pin 138, the lower end of which is in contact with the first end of fulcrum lever 136 and second end of which is in contact with the first end of bush assembly 150.

Figure 2 shows an exploded view of the measuring instrument 100 configured in accordance with the present invention and shown in Figure 1a. It includes dial indicator 110, bracket assembly 120, body assembly 130, cover 140 and bush assembly 150. Dial indicator 110 is fitted passing gauge pin 102 through bracket 104 fitted on top end of body assembly 130 by means of Allen screw 106. Guide plates 122 and 124 are fitted on either side of body assembly 130 on a respective slot provided therein and tightened by means of an arrangement of lock pin 127 and nut 128. Top plate 125 is fitted on top of guide plates 122, 124 by means of Allen screws 114. Grub screws 112 are also provided to be tightened on outer sides of plates 122, 124 for centering measuring instrument 100, as required. The arrangement of Allen screw 116 and nut 118 is subsequently used to rest measuring instrument 100 above bearing cap 180 (Fig. 6) for preventing further downward movement of measuring instrument 100. A dowel pin 109 is used to assemble profiled fulcrum lever 136, one end of which is in contact with gauge pin 138 inserted through and protruding out of the lower end of body 132. The other end of fulcrum lever 136 is in contact with bush assembly 150. Bush assembly 150 consists of mini bush 142 inserted with a mini plunger 144 after placing spring 146 thereon. Mini plunger 144 includes groove 147 at its end away from plunger head for locking circlip 148 therein for completing bush assembly 150. Cover 140 is provided for covering the lower end of body assembly 130 to protect it from contaminations. These plates 122, 124 also prevent the rotation of measuring instrument 100 while ensuring a proper orientation of mini plunger 144 thereof. Body 132 is used for locating the measuring instrument 100 in the part to be checked, e.g. crankcase 200. Guide plates 122, 124 also support top plate 125 and help in guiding and placing measuring instrument 100 in crankcase 200. These plates 122, 124 also prevent the rotation of measuring instrument 100 while ensuring a proper orientation of mini plunger 144 thereof. Bracket 104 and lock pin 106 are used for fixing dial indicator 110 on body 132 by means of Allen screw 102. Grub screw 108 is used for stopping the rotation of gauge pin 138 about its own axis and to prevent gauge pin 138 from coming out of body 132 of measuring instrument 100. A slot 139 is provided on gauge pin 138, which plays a significant role during inspection and operation of measuring instrument 100. Another arrangement of Allen screw 116 and nut 118 with its head screwed from under top plate 125 and adjustably tightened between Allen screws 114 are used for setting the vertical height of mini plunger 144 of measuring instrument 100 in relation to and according to specification of crankcase 200. Allen screw 116 and nut 118 are also used for accurate positioning of measuring instrument 100 on setting master 160 with mandrel 170 for initial calibration to zero reading to simulate the targeted machined center-to-center distance to be measured between oil-pump bore BOP and camshaft bore BC. Accordingly, measuring instrument 100 facilitates a precise, reliable and quick checking of center-to-center distance between oil pump bore BOP and camshaft bore BC.

Figure 3a shows a perspective view of the bush assembly 150 disposed at the lower end of measuring instrument 100 depicted in Figure 1a.

Figure 3b shows an exploded view of bush assembly 150 of Figure 3a. Bush assembly 150 has mini bush 142, mini plunger 144, spring 146 and circlip 148 finally fitted in groove 147 provided at the other end of mini plunger 144.

Figure 4a shows a perspective view of crankcase 200 depicting the oil pump bore BOP and camshaft bore BC machined therein and ready for measurement of center to center distance between bores BOP and BC.

Figure 4b shows a perspective view from top of crankcase 200 after positioning of measuring instrument 100 supported in on mandrel 170 of setting master 160 and precisely aligned in oil-pump bore BOP to measure the center-to-center distance between bores BOP and BC.

Figure 4c shows a perspective view of mandrel 160 from side of crankcase 200 with measuring instrument 100 positioned on mandrel 170 and placed in oil pump bore BOP and in contact with camshaft bore BC.

Figure 5a shows a cross-sectional view of crankcase 160 without mandrel 170 and depicting the relative dimension D to be checked for measuring the center-to-center distance between bores BOP and BC machined therein. Setting master 160 along with its mandrel 170 is configured to precisely simulate the center-to-center distance between oil pump bore BOP and camshaft bore BC machined in crankcase 200 of an internal combustion engine.

Figure 5b shows the front, side and top views of setting master 170 with bore 162 for inserting mandrel 160 therein.

Figure 5c shows the front, side and top views of setting master 160 of Fig. 5b with mandrel 170 placed therein, but before positioning of measuring instrument 100 thereon.

Figure 5d shows front, side and top views of the setting master of Fig. 5b with mandrel placed therein and after positioning of measuring instrument 100 thereon for setting the dimension and dial indicator 110 to zero reading thereof.

Figure 6 shows detailed view of measuring instrument 100 placed in crankcase 200 and retained in the required position by bearing cap 180. On inserting measuring instrument inside crankcase 200, once head of Allen screw 116 touches bearing cap 180, measuring instrument 100 cannot go down any further in oil pump bore BOP and positions bush assembly 150 precisely perpendicular to axis of camshaft and cover 120 contacts camshaft bore BC.

Figure 6a shows a view from top of setting master 170 of Figure 6, when seen along oil pump bore axis.

Figure 6b show a detail cross-sectional view detail X marked in Figure 6.

Figure 6c shows a side view of bracket assembly 120 of Figure 6.

Figure 6d shows another detail of Figure 6.

Figure 7a shows an enlarged view of the exploded bush assembly 110 press-fitted at the lower end of body 132 of body assembly 130 of Figure 6. The outer tip of mini plunger 144 is always protruded out due to the action of spring 146 against mini bush 142, but at the same time circlip 148 placed on mini plunger 144 prevents it from coming out of mini bush 142. Thereby, mini plunger 144 always remains in tension and protrudes out of cover 140 by spring compression. This mechanism helps to adjust measuring instrument 100 by means of setting master 170 to pre-set center-to-center distance between oil pump bore BOP and camshaft bore BC of crankcase 200 to be checked.

Figure 7b shows an enlarged sectional view of the lower end of Figure 7a. Gauge pin 102 is inserted in instrument body 132 from top with top end thereof touching dial indicator 122 (Fig. 3) and the bottom end thereof touching special fulcrum lever 106. Cover 140 provides protection to mini plunger 144 and does not allow dust from entering the body 132 of measuring instrument 100 thus prevents any adverse effects on the functioning thereof.
WORKING OF THE INVENTION

In accordance with the present invention, the method for measurement of distance between a bore involving a blind hole and another bore disposed at a distance therefrom, the method comprises the steps of:

• inserting mandrel in bore of the setting master;

• placing measuring instrument with the lower end thereof disposed in bore of the setting master;

• adjusting the vertical height of bush assembly with respect to mandrel by means of fasteners;

• calibrating and pre-setting the dial indicator for pre-setting measuring instrument to zero reading on the mini plunger tip contacting the outer diameter of the mandrel placed in second bore thereof;

• removing mandrel and measuring instrument from setting master.

Subsequently, the mandrel is inserted in first bore of the machined component and the distance measurement is conducted further by;

• inserting the lower end of the pre-set measuring instrument in second bore of the machined component;

• rotating fastener in top plate of bracket assembly until fastener head rests on bearing cap of crankshaft;

• reading the deviation of dial meter from preset zero reading thereof; and

• calculating the distance between two bores by computing the difference of the deviation of dial indicator reading from the preset zero reading thereof.

The method has proven particularly advantageous for accurately, reliably and quickly measuring the center-to-center distance between oil pump bore and camshaft bore machined in an automotive component having complex and inaccessible profile.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The system for calibration and measurement of center-to-center distance between two mutually perpendicular bores, e.g. an oil-pump bore and a camshaft bore machined during crankcase machining and conducted by means of a measurement instrument configured in accordance with the present invention offers the following advantages:

• system can be configured according to the distances to be measured between bores having blind holes machined in components having intricate profiles, e.g. crankcase with bores inaccessible to standard measurement tools.

• Facilitates an accurate, reliable and quick distance measurement.

• Substantially reduces the inspection time, due to omission of CMM inspection (requiring up to 120 minutes) altogether.

• Provides low-cost inspection method and measuring instrument.

• Allows even low-skill operators to conduct inspection of machined components.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.
It is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to imply including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description.

In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g. “horizontally”, “downwardly”, “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected”, refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

LIST OF REFERENCE NUMERALS

100 Measuring instrument
101 Hole for gauge pin 102
102 Gauge pin
104 Bracket
106 Allen screw as locking pin
108 Grub screw
109 Dowel pin
110 Dial indicator
112 Grub screws
114 Allen screws
115 Axis (in plates 122, 124) for grub screws 112
116 Allen screw
118 Nut
120 Bracket assembly
122, 124 Guide plates
125 Top plate
126 Locking pin
127 Locking pin axis
128 Locking nut
130 Body assembly
131 Through hole for gauge pin 138
132 Body
133 Hole for tightening bracket 104 on body 132
135 Counterbore hole in body 132 for inserting bush assembly 150
136 Fulcrum lever
137 Through hole for locking pin 126
138 Guide pin
139 Longitudinal slot in guide pin 138
140 Cover
141 Minor depression on cover 140
142 Mini bush
143 Hollow space within mini bush 142
144 Mini plunger
145 Axis for hole 135 (in body 132) and hole 149 (in cover 140)
146 Spring
147 Groove in mini plunger 144
148 Locking circlip
149 Longitudinal slot (149) gauge pin (138)
150 Bush assembly
160 Setting master
162 Bore
170 Mandrel 170
180 Bearing cap
200 Crankcase
B1 Oil-pump bore in machined components
B2 Camshaft bore in machined components
B11 Bore in setting master 160 to simulate bore B1 in components
B12 Bore in setting master 160 to simulate bore B2 to insert mandrel 170 therein
BOP Oil-pump bore
BC Camshaft bore
D Center-to-center distance between oil pump bore BOP and cam bore