Title of Invention

AN IMPROVED SHAFT-ASSEMBLING STRUCTURE FOR INTERNAL COMBUSTION ENGINE

Abstract

An object of the present invention is to provide a structure in which a rocker shaft (10) is found at first glance to be erroneously assembled on a cylinder head (4), resulting in improved operability during the assembling process. To this end, one distance between a one-side longitudinal wall portion at the top of the cylinder head (4) and the center of a first threaded hole located nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of the second threaded hole positioned second nearest to the aforesaid wall portion are assumed to be "A1" and "A2" respectively, while a distance between the other end of the rocker shaft (10), situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned nearest to the other end of the rocker shaft, and a yet another distance between the other end of the rocker shaft (10) and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft (10) are assumed to be "B1" and "B2" respectively, in which all relationships established by the following inequalities are satisfied : A1 < B1; A2 < B2 ; and (B2-B1) < (A2-A1).

Full Text

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved shaft-assembling structure for an internal combustion engine. More particularly, it relates to a shaft-assembling structure for an internal combustion engine, having threaded holes of a cylinder head defined and mounting hole portions of a rocker shaft formed at respective locations where all relationships defined by certain inequalities are satisfied such that the rocker shaft and the cylinder head are found at first glance to be in an erroneously assembled state on one another resulting in improved operability during the assembling process. 2. Description of Related Art In vehicles, multi-cylinders type of internal combustion engines have been in general use. In such an engine, a cam shaft and a rocker shaft are provided on the top of a cylinder -2- head. A shaft-assembling structure for use on the aforesaid engine is disclosed in published Japanese Examined Utility Model Application No. 5-7442. A rotatable camshaft-bridging device for a four cycle engine as disclosed in the publication includes the following: a lower shaft-receiving section provided on an upper surface of a cylinder head; a camshaft matched with the lower shaft-receiving section; a tentative pressing piece locked against the camshaft and fastened to the cylinder head for tentatively pressing the camshaft; and, a head cover fitted to the cylinder head and provided integrally with an upper shaft-receiving section. The upper shaft-receiving section is mated with the lower shaft-receiving section, thereby suspending the camshaft in a rotatable manner. Such a structure makes it possible to check the camshaft to see if it is normally assembled on the cylinder head. In conventional shaft-assembling structures for use on the internal combustion engine, a plurality of mounting hole portions are provided at definite intervals except for one pitch between one of the mounting hole portions and the next hole portion adjacent thereto, which pitch differs in distance between the hole portions from the remaining pitches in order to avoid erroneous assembling of the rocker shaft onto the cylinder head 3 in an inverted forward-rearward direction. Alternatively, there has been available a different rocker shaft machined to provide a mark which shows a proper front-to-rear relationship. Prior art is illustrated in greater detail in Figures 6(1), 6(b), 7(b) and 7(c) of the accompanying drawings. In Figures 6(a) and 6(b), assume that a rocker shaft 110 is formed with, e.g., five mounting hole portions, which are numbered from the first 114-1 to the fifth 114-5 through intervening holes 114-2, 114-3 and 114-4. In this case, one pitch P1 between the holes 114-1 and 114-2 is set to be made different from the other pitch P2 between the remainder 114-2, 114-3, 114-4 and 114-5 in such a manner as to satisfy the following inequality : P1 In Figure 7(c), the cylinder head of the internal combustion engine is defined with a plurality of threaded holes, e.g., two holes numbered from the first 112-1 to the fifth 112-5 through the intervening holes 112-2, 112-3 and 112-4. Now, assume that the rocker shaft is mounted onto the cylinder head in an inverted forward-rearward direction. Then, as illustrated in Figure 7(b), when the second to the fourth mounting hole portions 114-2, 114-3 and 114-4 are matched with the second to the fourth threaded holes 112-2, 112-3 and 112-4 respectively, then the first and the fifth mounting hole portions -4- 114-1, 114-5, located at both ends of the rocker shaft 110, are brought into a mismatch with the first and the fifth threaded holes 112-1, 112-5. Turning back to Figure 7(c), when the rocker shaft 110 is moved to match the mounting hole portions 114-1 and 114-5 with the threaded holes 112-1 and 112-5, respectively, then the remaining mounting hole portions 114-2, 114-3, and 114-4 at an intermediate portion of the rocker shaft 110 are all positioned offset from the second to the fourth threaded holes 112-2, 112-3, and 112-4, respectively. As a result, in order to avoid such improper assembling of the rocker shaft onto the cylinder head, the rocker shaft must be checked to see how it is matched at two locations or greater, which locations refer to one group of the first and the fifth mounting hole portions and another group of the second to the fourth mounting hole portions. This causes an inconvenience in which the rocker shaft is assembled inefficiently. SUMMARY OF THE INVENTION In order to obviate the above-mentioned inconvenience, the present invention provides a shaft-assembling structure for an internal combustion engine, the engine including a cylinder block, a cylinder head attached to an upper surface of the cylinder block, and an oil pan disposed on the bottom of the cylinder block, the shaft-assembling structure including a plu- 5 rality of threaded holes provided at the top of the cylinder head, and a plurality of mounting hole portions provided through a rocker shaft at locations corresponding to the respective threaded holes, in which the threaded holes and the mounting hole portions are used to dispose the rocker shaft on the cylinder head by means of a fixing bolt, the improvement comprising: one-side and the other-side longitudinal wall portions provided on the top of the cylinder head, the wall portions protruding upward at both ends of the cylinder head in the longitudinal direction of the cylinder head, wherein one distance between the one-side longitudinal wall portion and the center of a first threaded hole located the nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of a second threaded hole positioned the second nearest to the aforesaid wall portion are assumed to be "A1" and "A2", respectively, while a further distance between the other end of the rocker shaft, situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned the nearest to the other end of the rocker shaft, and a yet further distance between the other end of the rocker shaft and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft are assumed to be "B1" and "B2", respectively, in which all relationships established by the following inequalities are satisfied: A1 6 A2 Thus, if the rocker shaft is mounted on the cylinder head in an inverted forward-rearward direction, then all of the threaded holes are brought into a mismatch with all of the mounting hole portions because of the settings that meet all relationships defined by the following inequalities : A1 Further, when the rocker shaft is displaced so as to forcedly match the mounting hole portions with the threaded holes in a state of the rocker shaft being positioned in the inadvertently opposite front-to-rear relationship, then the other end of the rocker shaft is brought into interference with the one-side wall portion of the cylinder head, thereby precluding the rocker shaft from being mounted on the cylinder head. Consequently, such an erroneously assembled state of the rocker shaft can be found at first glance. Thus, improved operability during the assembling process is provided. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 is an illustration, showing an assembled -7- state of a cylinder head pursuant to an embodiment of the present invention, in which Figure 1(a) is a cross-sectional view, showing a rocker shaft in a normally assembled state, Figure 1(b) is a cross-sectional view, showing the rocker shaft in an erroneously assembled state by way of a first example, Figure 1(c) is a cross-sectional view, showing the rocker shaft in an erroneously assembled state by way of a second example, and Figure 1(d) is a cross-sectional view taken along line 1-1 of Figure 5, illustrating a cross-sectional view of the cylinder head. Figure 2 is a plan view, illustrating an internal combustion engine, with a cylinder head cover being partially cut away from the engine; Figure 3 is a cross-sectional front view, showing the engine; Figure 4 is a cross-sectional left side view, showing the engine; Figure 5 is a plan view, illustrating a cylinder head; Figure 6 is an illustration, showing a rocker shaft according to the prior art that underlies the present invention, in which: Figure 6(a) is a front view; and, 8 Figure 6(b) is a cross-sectional view taken along line "Vib"-"Vib" of Figure 6(a); Figure 7 is an illustration, showing a assembled state of the rocker shaft, in which: Figure 7(a) is a schematic view, showing the rocker shaft in an erroneously assembled state by way of a first example; Figure 7(b) is a schematic view, showing the rocker shaft in the erroneously assembled state by way of a second example; and, Figure 7(c) is a schematic view, illustrating positions where threaded holes of the cylinder head are located. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described in detail with reference to the drawings. Figures 1 to 5 illustrate the embodiment. In Figures 2 to 4, reference numerals 2 and 4 denote an internal combustion engine and a cylinder head, respectively. The engine 2 includes a cylinder block (not shown), the cylinder head 4 attached to an upper surface of the cylinder block, a cylinder head cover 6 fitted to the top of the cylinder 9 head 4, and an oil pan (not shown) provided on the bottom of the cylinder block. In addition, a camshaft 8 is provided on the top of the cylinder head 4 parallel to the longitudinal direction thereof. Further, a rocker shaft 10 is disposed parallel to the camshaft 8. More specifically, a plurality of threaded holes 12 are provided at the top of the cylinder head 4. The rocker shaft 10 is provided with a plurality of mounting hole portions 14 at locations corresponding to the respective threaded holes 12. The holes 12 and 14 are used to dispose the rocker shaft 10 on the cylinder head 4 by means of fixing bolts 16. In this connection, reference numerals 18 and 20 in the drawings denote a rocker arm fitted to the rocker shaft 10 and a distributor, respectively. The cylinder head 4 has one-side and another-side longitudinal wall portions 22, 24 provided on the top thereof. The wall portions 22, 24 protrude upwardly at both sides of the cylinder head 4 in the longitudinal direction thereof. Then, assume that one distance between the one-side longitudinal wall portion 22 at the left in Figure 1 and the center of a first threaded hole 12-1 located the nearest to the wall portion 22 is 10 "A1", while another distance between the same wall portion 22 and the center of a second threaded hole 12-2 positioned the second nearest to the wall portion 22 is "A2". Further, a distance between the other end 10b of the rocker shaft 10 and the center of a first mounting hole portion 14-1 positioned the nearest to the end 10b is assumed to be "B1". The other end 10b of the rocker shaft 10 is situated toward the other-side longitudinal wall portions 24 at the right in Figure 1. Yet further, a distance between the end l0b and the center of a second mounting hole 14-2 located the second nearest to the end 10b is assumed to be "B2". Then, the above structure is provided in which all relationships established by the following inequalities are satisfied: A1 A2 (B2-B1) More specifically, a plurality of rocker shaft bearing portions 26 are formed on the top of the cylinder head 4, as shown in Figures 1 and 5. The bearing portion 26 has a semi-arcuate shape. For each of the bearing portions 26, five threaded holes, e.g., which are numbered from the first 12-1 to the fifth 12-5 through the remaining holes 12-2, 12-3, and 12-4, are formed sideward from the one-side longitudinal wall portion 22. Turning now to the rocker shaft 10, five mounting 11 11 hole portions, e.g., which are numbered from the first 14-1 to the fifth 14-5 through the remainder 14-2, 14-3, and 14-4, are defined sideward from the other end 10b of the rocker shaft 10, as illustrated in Figure 1(a). At this time, distance "A1" is set to he smaller than distance "B1". Further, distance "A2" is set to be smaller than distance "B2". Moreover, with regard to the relationship defined by the following inequality: (B2-B1) Further, assume that a distance between the other-side longitudinal wall portion 24 and the center of the fifth threaded hole 12-5 situated the nearest to the wall portion 24 is "A3" (see Figure 5). Yet further, assume that a distance between one end 10a of the rocker shaft 10, situated toward the 12 one-side longitudinal wall portion 22, and the center of the fifth mounting hole portion 14-5 located the nearest to the end 10a is "B3". In this way, distances A1, A3, B1, and B3 are set to meet two inequalities that follow; AKA3; and, B3 Reference numeral 28 is an ignition plug. Next, the operation of the present invention will be described. When the rocker shaft 10 is positioned on the cylinder head 4, the one-side and the other-side longitudinal wall portion 22 and 24 of the cylinder head 4 are initially located respectively at the left and right in Figure 1, as shown in Figure 1(d). Next, as illustrated in Figure 1(a), the rocker shaft 10 is regularly assembled onto the cylinder head 4 in which one end 10a of the rocker shaft 10 is positioned at the left in Figure 1, while the other end 10b thereof is located at the right in Figure 1. Then, as shown in Figures 1(a) and 1(d), the first, second, third, fourth, and fifth threaded holes 12-1, 12-2, 12-3, 12-4, and 12-5 are matched to the fifth, fourth, third, second, and first 13 mounting hole portions 14-5, 14-4, 14-3, 14-2, and 14-1, respectively. In further detail, referring to Figures 1(a) and 1(d), the fifth, fourth, third, second, and first mounting hole portions 14-5, 14-4, 14-3, 14-2, and 14-1 coincide with the first, second, third, fourth, and fifth threaded holes 12-1, 12-2, 12-3, 12-4, and 12-5 at first, second, third, fourth, and fifth tightening points "T1", "T2". "T3", "T4", and "T5", respectively. Next, as illustrated in Figures 1(b) and 1(c), the rocker shaft 10 is driven into an erroneously assembled state in which one end 10a and the other end l0b are positioned respectively at the right and the left in Figure 1. In this case, when the other end 10b is forced to fit the one-side wall portion 22 as shown in Figure 1(b), then none of the mounting hole portions 14 coincides with any of the threaded holes 12. Further, in order to match the mounting holes portions 14 with the threaded holes 12, the rocker shaft 10 is displaced to bring three threaded holes located in the central portion of the cylinder head 4, i.e., the second to the fourth threaded holes 12-2, 12-3, and 12-4, into coincidence with the respective mounting hole portions 14, as illustrated in Figure 1(c). However, in this case, the other end 10b interferes with the one-side 14 wall portion 22 because of the setting of the following inequality: A1 Thus, if the rocker shaft 10 is mounted on the cylinder head 4 in an inverted forward-rearward direction, then all of the threaded holes 12 are brought into a mismatch with all of the mounting hole portions 14 because of the settings that satisfy all relationships defined by the following inequalities: A1 Further, when the rocker shaft 10 is moved so as to forcedly match the mounting hole portions 14 with the threaded holes 12 in a state of the rocker shaft 10 being positioned in the inverted forward-rearward direction, then the other end 10b is brought into interference with the one-side wall portion 22, thereby precluding the rocker shaft 10 from being mounted on the cylinder head 4. Then, the rocker shaft 10 is instantaneously 15 notified of being in an erroneously assembled state. Moreover, only a change in position where the threaded holes 12 and the mounting hole portions 14 are drilled is required to avoid such erroneously assembly. This feature eliminates the possibility of a complicated structure, and thus provides easy manufacture, while maintaining reduced costs: This is advantageous from an economical viewpoint as well. As described above in detail, the shaft-assembling structure for an internal combustion engine, pursuant to the present invention, the engine including a cylinder block, a cylinder head attached to an upper surface of the cylinder block, and an oil pan disposed on the bottom of the cylinder block, the shaft-assembling structure including a plurality of threaded holes provided at the top of the cylinder head, and a plurality of mounting hole portions provided through a rocker shaft at locations corresponding to the respective threaded holes, in which the threaded holes and the mounting hole portions are used to dispose the rocker shaft on the cylinder head by means of a fixing bolt, the improvement comprising: one-side and the other-side longitudinal wall portions provided on the top of the cylinder head, the wall portions protruding upward at both ends of the cylinder head in the longitudinal direction of the cylinder head, wherein one distance between the one-side longitudinal wall por- 16 tion and the center of a first threaded hole located the nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of a second threaded hole positioned the second nearest to the aforesaid wall portion are assumed to be "Al" and 'A2', respectively, while a further distance between the other end of the rocker shaft, situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned the nearest to the other end of the rocker shaft, and a yet further distance between the other end of the rocker shaft and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft are assumed to be "B1" and "B2", respectively, in which all relationships established by the following inequalities are satisfied: A1 17 tions with the threaded holes in a state of the rocker shaft being positioned in the inverted forward-rearward direction, then the other end of the rocker shaft is brought into interference with the one-side wall portion of the cylinder head, thereby precluding the rocker shaft from being mounted on the cylinder head. Then, the rocker shaft is instantaneously notified of being in an erroneously assembled state. Moreover, only a change in position where the threaded holes and the mounting hole portions are drilled is required to avoid such erroneously assembly. This feature eliminates the possibility of a complicated structure, and thus provides easy manufacture, while maintaining reduced costs. This is advantageous from an economical viewpoint as well. 18 WE CLAIM : 1. An improved shaft-assembling structure for an internal combustion engine, said engine having a cylindrical block, a cylinder head attached to an upper surface of the cylinder block, and an oil pan disposed on the bottom of the cylinder block, the shaft-assembling structure comprising a plurality of threaded holes provided at the top of the cylinder head, and a plurality of mounting hole portions provided through a rocker shaft at locations corresponding to the respective threaded holes, in which the threaded holes and the mounting hole portions are used to dispose the rocker shaft on the cylinder head by means of a fixing bolt, the arrangement being such that : one-side and the other-side longitudinal wall portions provided on top of the cylinder head, the wall portions protruding upward at both ends of the cylinder head in the longitudinal direction of the cylinder head, one distance between the one-side longitudinal wall portion and the center of the first threaded hole located nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of the second threaded hole positioned second nearest to the aforesaid wall portion are assumed to be "A1" and "A2" respectively, while a distance between the other end of the rocker shaft, situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned nearest to the other end of the rocker shaft, and a yet another distance between the other end of the rocker shaft and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft are assumed to be "B1" and "B2" respectively, in which all relationships established by the following inequalities are satisfied : A1 -19- 2. An improved shaft-assembling structure for an internal combustion engine, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 3. An internal combustion engine mounted on a shaft-assembling structure as claimed in any one of the preceding claims. Dated this 13th day of January 1999. (S.R.GUPTA) of DP. AHUJA&CO. Applicants' Agent -20- An object of the present invention is to provide a structure in which a rocker shaft (10) is found at first glance to be erroneously assembled on a cylinder head (4), resulting in improved operability during the assembling process. To this end, one distance between a one-side longitudinal wall portion at the top of the cylinder head (4) and the center of a first threaded hole located nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of the second threaded hole positioned second nearest to the aforesaid wall portion are assumed to be "A1" and "A2" respectively, while a distance between the other end of the rocker shaft (10), situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned nearest to the other end of the rocker shaft, and a yet another distance between the other end of the rocker shaft (10) and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft (10) are assumed to be "B1" and "B2" respectively, in which all relationships established by the following inequalities are satisfied : A1 An object of the present invention is to provide a structure in which a rocker shaft (10) is found at first glance to be erroneously assembled on a cylinder head (4), resulting in improved operability during the assembling process. To this end, one distance between a one-side longitudinal wall portion at the top of the cylinder head (4) and the center of a first threaded hole located nearest to the one-side longitudinal wall portion, and another distance between the same wall portion and the center of the second threaded hole positioned second nearest to the aforesaid wall portion are assumed to be "A1" and "A2" respectively, while a distance between the other end of the rocker shaft (10), situated toward the other-side longitudinal wall portion, and the center of a first mounting hole portion positioned nearest to the other end of the rocker shaft, and a yet another distance between the other end of the rocker shaft (10) and the center of a second mounting hole portion positioned the second nearest to the other end of the rocker shaft (10) are assumed to be "B1" and "B2" respectively, in which all relationships established by the following inequalities are satisfied : A1

Documents:

00029-cal-1999-abstract.pdf

00029-cal-1999-claims.pdf

00029-cal-1999-correspondence.pdf

00029-cal-1999-description(complete).pdf

00029-cal-1999-drawings.pdf

00029-cal-1999-form-1.pdf

00029-cal-1999-form-2.pdf

00029-cal-1999-form-3.pdf

00029-cal-1999-form-5.pdf

00029-cal-1999-p.a.pdf

00029-cal-1999-priority document others.pdf

00029-cal-1999-priority document.pdf

29-cal-1999-granted-abstract.pdf

29-cal-1999-granted-claims.pdf

29-cal-1999-granted-correspondence.pdf

29-cal-1999-granted-description (complete).pdf

29-cal-1999-granted-drawings.pdf

29-cal-1999-granted-examination report.pdf

29-cal-1999-granted-form 1.pdf

29-cal-1999-granted-form 2.pdf

29-cal-1999-granted-form 3.pdf

29-cal-1999-granted-form 5.pdf

29-cal-1999-granted-gpa.pdf

29-cal-1999-granted-letter patent.pdf

29-cal-1999-granted-others.pdf

29-cal-1999-granted-priority document.pdf

29-cal-1999-granted-reply to examination report.pdf

29-cal-1999-granted-specification.pdf

29-cal-1999-granted-translated copy of priority document.pdf