EP1207292A2

EP1207292A2 - Crank shaft supporting structure for horizontal opposed type internal combustion engine

Info

Publication number: EP1207292A2
Application number: EP01121362A
Authority: EP
Inventors: Minoru Matsuda; Makoto Sanada
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2000-11-15
Filing date: 2001-09-06
Publication date: 2002-05-22
Anticipated expiration: 2021-09-06
Also published as: DE60124847T2; CA2360402C; EP1207292B1; EP1207292A3; ATE347028T1; CA2360402A1; DE60124847D1

Abstract

Object: In a horizontal opposed type internal combustion engine, to enable rigid support of a middle journal of a crank shaft through rational utilization of first and second case halves constituting a crankcase, and to thereby contribute to a simplification in structure and a reduction in weight.

Solving Means: In a horizontal opposed type internal combustion engine in which a crankcase (6) is split at a plane (P) containing the axis line (A) of a crank shaft(1) into first and second case halves (6L, 6R) connected with first and second cylinder blocks (7L, 7R), the first and second case halves (6L, 6R) are provided integrally with first and second journal supporting walls (13Lm, 13Rm) for supporting a middle journal (3m) of the crank shaft (1), the first and second journal supporting walls (13Lm, 13Rm) fronting on cylinder bores (10Lr, 10Rf) of the first and second cylinder blocks (7L, 7R), and the first and second journal supporting walls are coupled by a plurality of first bolts (19L) inserted from the side of the cylinder bore (10Lr) of the first cylinder block(7L)and disposed on both sides of and in proximity to the middle journal (3m).

Description

The present invention relates to a crank shaft supporting structure for a horizontal opposed type internal combustion engine used for automobiles, motorcycle, airplanes and the like. Particularly, the invention relates to a crank shaft supporting structure for supporting a journal at an intermediate portion of a crank shaft in a horizontal opposed type internal combustion engine comprising a crank shaft, pluralities of first and second pistons connected to the crank shaft, disposed opposite to each other with the crank shaft therebetween and arranged with an offset from each other along the axial direction of the crank shaft, a crankcase for containing and supporting the crank shaft, and first and second cylinder blocks connected to and disposed on both sides of the crankcase and having cylinder bores for slidable fitting therein of the first and second pistons, the crankcase being split along a plane containing the axis line of the crank shaft into first and second case halves connected respectively with the first and second cylinder blocks.
As a structure for supporting a middle journal of a crank shaft in a horizontal opposed type internal combustion engine as above, hitherto, there have been known (1) a structure in which a first case half is provided integrally with a journal supporting wall for supporting a half periphery portion of a middle journal of a crank shaft and a bearing cap for supporting the other half periphery portion of the journal is bolt-connected to the journal supporting wall (See, for example, Japanese Patent Laid-open No. 2000-110582), and (2) a structure in which first and second case halves are provided integrally with first and second journal supporting walls for supporting one half periphery portion and the other half periphery portion of a middle journal of a crank shaft and are bolt-connected at their outside portions.
The structure of (1) above has drawbacks in that, since the bearing cap to be connected to the first case half is needed, the number of component parts is increased, while the second case half cannot contribute greatly to reinforcement of the support rigidity for the crank shaft. On the other hand, the structure of (2) above has drawbacks in that, since the distance from the middle journal of the crank shaft to the bolt connection portions of the case halves is necessarily large, not only the journal supporting wall but also portions of the crankcase must be large in thickness for the purpose of obtaining sufficient support rigidity for the crank shaft, resulting in an increase of the weight of the internal combustion engine.
The present invention has been made in consideration of the above-mentioned points. Accordingly, an object of the invention is to provide a crank shaft supporting structure for horizontal opposed type internal combustion engine which utilizes the first and second case halves of the crankcase rationally so as to support rigidly the middle journal of the crank shaft, thereby contributing to simplification in structure and reduction in weight.
In order to attain the above object, the present invention is characterized firstly in that, in a horizontal opposed type internal combustion engine comprising a crank shaft, pluralities of first and second pistons connected to the crank shaft, disposed opposite to each other with the crank shaft therebetween and arranged with an offset from each other along the axial direction of the crank shaft, a crankcase for containing and supporting the crank shaft, and first and second cylinder blocks connected to and disposed on both sides of the crankcase and having cylinder bores for slidable fitting therein of the first and second pistons, the crankcase being split along a plane containing the axis line of the crank shaft into first and second case halves connected respectively with the first and second cylinder blocks, the first and second case halves are provided integrally with first and second journal supporting walls rotatably supporting a middle journal of the crank shaft therebetween, the first and second journal supporting walls fronting on the cylinder bores of the first and second cylinder blocks, and the first and second journal supporting walls are connected by a plurality of first bolts inserted from the side of the cylinder bore of the first cylinder block and disposed on both sides of and in proximity to the middle journal.
According to the first characteristic feature, the first and second journal supporting walls for supporting therebetween the middle journal of the crank shaft can easily be bolt-connected, without being interfered in any way by the first and second cylinder blocks.
Besides, since the journal supporting walls are bolt-connected on both sides of and in proximity to the middle journal of the crank shaft, rigidity of support for the middle journal of the crank shaft can be enhanced effectively. As a result, the crankcase can be reduced in wall thickness, leading to a reduction in weight.
In addition, the bearing cap for exclusive use for supporting the crank shaft is not needed, and, therefore, it is possible to contrive a reduction in the number of component parts and a simplification in structure.
In addition to the first characteristic feature, the invention is characterized secondly in that the first and second journal supporting walls are connected by a plurality of second bolts inserted from the side of the cylinder bore of the second cylinder block and arranged on both sides of and in proximity to the middle journal.
According to the second characteristic feature, even though the amount of exposure of the first and second supporting walls into the cylinder bores of the first and second cylinder blocks is small and the bolts to be used is small in diameter, the journal supporting walls can be connected by at least four bolts inserted from the first and second cylinder blocks, and, as a result, the journal supporting walls can be provided with sufficient binding force.
Modes for carrying out the invention will now be described based on some embodiments illustrated by the attached drawings, in which:
Fig. 1 is a vertical sectional view of a horizontal opposed type internal combustion engine comprising a crank shaft supporting structure according to the invention.
Fig. 2 is a sectional view taken along line 2-2 of Fig. 1.
Fig. 3 is a sectional view taken along line 3-3 of Fig. 1.
Fig. 4 is a sectional view taken along line 4-4 of Fig. 1.
Fig. 1 is a vertical sectional view of a horizontal opposed type internal combustion engine comprising a crank shaft supporting structure according to the invention; Fig. 2 is a sectional view taken along line 2-2 of Fig. 1; Fig. 3 is a sectional view taken along line 3-3 of Fig. 1; and Fig. 4 is a sectional view taken along line 4-4 of Fig. 1.
First, in Fig. 1, symbol E denotes a horizontal opposed type 4-cylinder internal combustion engine, for automobile to which the invention has been applied. The internal combustion engine E comprises a crank shaft 1 disposed in the front-rear direction of the vehicle. Four cranks of the crank shaft 1 will be called No. 1 crank 2₁, No. 2 crank 2₂, No. 3 crank 2₃, and No. 4 crank 2₄, in this order from the front side of the vehicle. The No. 1 crank 2₁ and the No. 4 crank 2₄ as well as the No. 2 crank 2₂ and the No. 3 crank 2₃ are in the same phase with each other, and there is a phase difference of 180° between the first and fourth cranks 2₁, 2₄ and the second and third cranks 2₂ and 2₃.
In this crank shaft 1, a front journal 3f is adjacently provided on the front side of the No. 1 crank 2₁, a middle journal 3m is provided at a middle portion between the No. 2 and No. 3 cranks 2₂, 2₃, and a rear journal 3r is adjacently provided on the rear side of the No. 4 crank 2₄.
The No. 1 and No. 3 cranks 2₁, 2₃ are respectively connected with a front-rear pair of first pistons 4Lf, 4Lr through connecting rods 5Lf, 5Lr, whereas the No. 2 and No. 4 cranks 2₂, 2₄ are respectively connected with a front-rear pair of second pistons 4Rf, 4Rr through connecting rods 5Rf, 5Rr. The first pistons 4Lf, 4Lr and the second pistons 4Rf, 4Rr are disposed oppositely on the left and right sides with the axis line A of the crank shaft 1 therebetween. Thus, the first piston 4Lf and the second piston 4Rf are set off from each other along the crank axis line A by the axial distance S between the corresponding No. 1 crank 2₁ and No. 2 crank 2₂.
As shown in Fig. 4, a crankcase 6 for containing the crank shaft 1 is split along a vertical plane P containing the crank axis line A into a first case half 6L on the side of the first pistons 4Lf, 4Lr and a second case half 6R on the side of the second pistons 4Rf, 4Rr. As shown in Figs. 1 to 3, the first and second case halves 6L, 6R are connected with first and second cylinder blocks 7L, 7R by pluralities of bolts 8L, 8L ... and 8R, 8R ... at the circumference of each cylinder block. To the first cylinder block 7L are integrally joined, by insert-casting, cylinder sleeves 9Lf, 9Lr having cylinder bores 10Lf, 10Lr for slidable fitting therein of the first pistons 4Lf, 4Lr. On the other hand, to the second cylinder block 7R integrally joined, by insert-casting, cylinder sleeves 9Rf, 9Rr having cylinder bores 10Rf, 10Rr for slidable fitting therein of the second pistons 4Rf, 4Rr. The cylinder sleeves 9Lf, 9Lr, 9Rf, 9Rr are protruding from the inner ends of the first and second cylinder blocks 7L, 7R, and the protruding portions are received in sleeve receiving holes 11L, 11R provided in the first and second case halves 6L, 6R. Thus, attendant on the above-mentioned offset between the first and second pistons 4Lf, 4Lr and 4Rf, 4Rr, the cylinder bores 10Lf, 10Rf of the first and second cylinder blocks 7L, 7R are also set off from each other by the above-mentioned distance S along the crank axis line A.
The first case half 6L is provided integrally with three first journal supporting walls 13Lf, 13Lm, 13Lr for supporting half periphery portions of the front journal 3f, middle journal 3m and rear journal 3r through split bushes 12, respectively. The second case half 6R, also, is provided integrally with three second journal supporting walls 13Rf, 13Rm, 13Rr for supporting the other half periphery portions of the front journal 3f, middle journal 3m and rear journal 3r through split bushes 12, respectively. In this case, the first and second journal supporting walls 13Lf, 13Rf at a front portion are located at a middle position along the crank axis line A between front walls 7Lf, 7Rf of the first and second cylinder blocks 7L, 7R. The first and second journal supporting walls 13Lm, 13Rm at an intermediate portion are located at a middle position along the crank axis line A between middle walls 7Lm, 7Rm of the first and second cylinder blocks 7L, 7R. The first and second journal supporting walls 13Lr, 13Rr at a rear portion are located at a middle position along the crank axis line A between rear walls 7Lr, 7Rr of the first and second cylinder blocks 7L, 7R. As a result, portions of the first journal supporting walls 13Lf, 13Lm at the front and intermediate portions are exposed to the side of the cylinder bores 10Lf, 10Lr of the first cylinder block 7L, and first journal supporting wall 13Lr at the rear portion is located on the rear side of the rear wall 7Lr of the first cylinder block 7L. On the other hand, portions of the second journal supporting walls 13Rm, 13Rr at the intermediate and rear portions are exposed to the side of the cylinder bores 10Rf, 10Rr of the second cylinder block 7R, and the journal supporting wall 13Rf at the front portion is located on the front side of the front wall 7Rf of the second cylinder block 7R.
The first journal supporting wall 13Lr at the rear portion is provided with a pair of bolt holes 14L, 14L disposed in proximity to and on opposite sides of the rear journal 3r of the crank shaft 1, and the second journal supporting wall 13Rr at the rear portions is provided with a pair of screw holes 15R, 15R coinciding with the bolt holes 14L, 14L. On the other hand, the second journal supporting wall 13Rf at the front portion is provided with a pair of bolt holes 14R, 14R disposed in proximity to and on opposite sides of the front journal 3f of the crank shaft 1, and the first journal supporting wall 13Lf at the front portion is provided with a pair of screw holes 15L, 15L coinciding with the bolt holes 14R, 14R.
The first journal supporting wall 13Lm at the middle portion is provided with a pair of bolt holes 16L, 16L opening into the rear cylinder bore 10Lr of the first cylinder block 7L and disposed in proximity to and on opposite sides of the middle journal 3m of the crank shaft 1, and the second journal supporting wall 13Rm at the middle portion is provided with a pair of screw holes 17R, 17R coinciding with the bolt holes 16L, 16L. On the other hand, the second journal supporting wall 13Rm at the middle portion is provided with a pair of bolt holes 16R, 16R opening into the front cylinder bore 10Rf of the second cylinder block 7R and disposed in proximity to and on opposite sides of the middle journal 3m, and the first journal supporting wall 13Lm at the middle portion is provided with a pair of screw holes 17L, 17L coinciding with the bolt holes 16R, 16R. Thus, the first and second journal supporting walls 13Lm, 13Rm at the intermediate portion are provided with pairs of bolt holes 16L, 16L and 16R, 16R and screw holes 17L, 17L and 17R, 17R. In order that the bolt holes 16L, 16L and 16R, 16R and the screw holes 17L, 17L and 17R, 17R adjacent to each other would not interfere with each other, these bolt holes and screw holes are formed to be smaller in diameter than the bolt holes 14L, 14L and 14R, 14R and the screw holes 15L, 15L and 15R, 15R provided in the first and second journal supporting holes 13Lf, 13Lr and 13Rf, 13Rr at the front and rear portions.
Bolts 18L, 18L; 18R, 18R; 19L, 19L; 19R, 19R passed through the bolt holes 14L, 14L; 14R, 14R; 16L, 16L; 16R, 16R are fitted into the corresponding screw holes 15L, 15L; 15R, 15R; 17L, 17L; 17R, 17R, whereby the opposed first and second journal supporting walls 13Lf, 13Lm, 13Lr and 13Rf, 13Rm, 13Rr are connected to each other.
The first and second case halves 6L, 6R are connected to each other by a plurality of bolts 20, 20 ... at their peripheral portions.
Now, the operation or effects of the embodiment will be described below.
In assembling the internal combustion engine E, first, the connecting rods 5Lf, 5Rf, 5Lr, 5Rr are only connected to the No. 1 to No. 4 cranks 2₁ to 2₄ of the crank shaft 1, and the first and second case halves 6L, 6R are connected in the manner of sandwiching the crank shaft 1 therebetween. Namely, the bolts 18L, 18L; 18R, 18R; 19L, 19L; 19R, 19R passed through the bolt holes 14L, 14L; 14R, 14R; 16L, 16L; 16R, 16R are fitted into the screw holes 15L, 15L; 15R, 15R; 17L, 17L; 17R, 17R, whereby the opposed first and second journal supporting walls 13Lf, 13Lm, 13Lr and 13Rf, 13Rm, 13Rr are coupled to each other.
In this case, particularly, in coupling the first and second journal supporting walls 13Lm, 13Rm situated at the intermediate portion, fitting of the bolts 19L, 19L and 19R, 19R is carried out easily by utilizing the space inside the rear sleeve receiving hole 11L of the first case half 6L and the space inside the front sleeve receiving hole 11R of the second case half 6R. Therefore, the coupling of the first and second supporting walls 13Lm, 13Rm situated at the middle portion can be easily carried out without being interfered in any way by the first and second cylinder blocks 7L, 7R. In addition, although the amount of exposure of the first and second middle journal supporting walls 13Lm, 13Rm to the side of the left and right sleeve receiving holes 11L, 11R is small and therefore small-diameter bolts must be used in coupling the journal, supporting walls 13Lm, 13Rm together, the journal supporting walls 13Lm, 13Rm can be provided with sufficient binding force because the journal supporting walls 13Lm, 13Rm are coupled by a total of four bolts 19L, 19L and 19R, 19R which are inserted from the side of the left and right sleeve receiving holes 11L, 11R.
Thus, the first and second journal supporting walls 13Lm, 13Rm at the middle portion are also bolt-connected in proximity to and on both sides of the crank shaft 1, in the same manner as the first and second journal, supporting walls 13Lf, 13Rf and 13Lr, 13Rr at the front and rear portions. Therefore, rigidity of support for the middle journal 3m of the crank shaft 1 can be enhanced effectively. As a result, the crankcase 6 can be made small in thickness, leading to a reduction in weight. In addition, since there is no need for any bearing cap for exclusive use for supporting the middle journal 3m, it is possible to contrive a reduction in the number of component parts and a simplification in structure.
After the first and second case halves 6L, 6R are coupled, the pistons 4Lf, 4Rf, 4Lr, 4Rr are connected to the connecting rods 5Lf, 5Rf, 5Lr, 5Rr, and the first cylinder block 7L is connected to the first case half 6L by the bolts 8L, 8L ... while fitting the first pistons 4Lf, 4Lr in the cylinder bores 10Lf, 10Lr of the first cylinder block 7L. Similarly, the second cylinder block 7R is connected to the second case half 6R by the bolts 8R, 8R ... while fitting the second pistons 4Rf, 4Rr in the cylinder bores 10Rf, 10Rr of the second cylinder block 7R.
The present invention is not restricted to or by the above-mentioned embodiments, and various modifications in design can be made without stepping out of the gist of the invention. For instance, the first cylinder block 7L can be formed integrally with the first case half 6L, and the second cylinder block 7R can be formed integrally with the second case half 6R. In that case, when transverse holes capable of inserting piston pins therein are provided in portions of the cylinder blocks 7L, 7R proximate to the case halves 6L, 6R, connection of the pistons 4Lf, 4Lr and 4Rf, 4Rr with the connecting rods 5Lf, 5Lr and 5Rf, 5Rr is carried out in spite of the presence of the cylinder blocks 7L, 7R. Besides, the horizontal opposed type internal combustion engine according to the present invention can be applied also to internal combustion engines having six or more cylinders. Furthermore, by disposing a crank shaft along a center line of a vehicle, the horizontal opposed type internal combustion engine according to the invention can be used not only for automobiles but also for motorcycles and airplanes.
As has been described above, according to the first characteristic feature of the invention, in a horizontal opposed type internal combustion engine comprising a crank shaft, pluralities of first and second pistons connected to the crank shaft, disposed opposite to each other with the crank shaft therebetween and arranged with an offset from each other along the axial direction of the crank shaft, a crankcase for containing and supporting the crank shaft, and first and second cylinder blocks connected to and disposed on both sides of the crankcase and having cylinder bores for slidable fitting therein of the first and second pistons, the crankcase being split along a plane containing the axis line of the crank shaft into first and second case halves connected respectively with the first and second cylinder blocks, the first and second case halves are provided integrally with first and second journal supporting walls rotatably supporting a middle journal of the crank shaft therebetween, the first and second journal supporting walls fronting on the cylinder bores of the first and second cylinder blocks, and the first and second journal supporting walls are connected by a plurality of first bolts inserted from the side of the cylinder bore of the first cylinder block and disposed on both sides of and in proximity to the middle journal. With this construction, the first and second journal supporting walls for supporting the middle journal of the crank shaft therebetween can be bolt-connected easily without being interfered in any way by the presence of the first and second cylinder blocks. Both the journal supporting walls are bolt-connected on both sides of and in proximity to the middle journal of the crank shaft, whereby rigidity of support for the middle journal of the crank shaft can be enhanced effectively. Therefore, the crankcase can be made small in thickness, leading to a reduction in weight.' Besides, there is no need for any bearing cap for exclusive use for supporting the crank shaft, which enables a reduction in the number of component parts and a simplification in structure.
According to the second characteristic feature, in addition to the first characteristic feature, the first and second journal supporting walls are connected by a plurality of second bolts inserted from the side of the cylinder bore of the second cylinder block and arranged on both sides of and in proximity to.the middle journal. Therefore, even though the amount of exposure of the first and second supporting walls into the cylinder bores of the first and second cylinder blocks is small and the bolts used are small in diameter, the journal supporting walls can be connected using at least four bolts inserted from the sides of the first and second cylinder blocks, whereby the journal supporting walls can be provided with sufficient binding force.
Object: In a horizontal opposed type internal combustion engine, to enable rigid support of a middle journal of a crank shaft through rational utilization of first and second case halves constituting a crankcase, and to thereby contribute to a simplification in structure and a reduction in weight.
Solving Means: In a horizontal opposed type internal combustion engine in which a crankcase 6 is split at a plane P containing the axis line A of a crank shaft 1 into first and second case halves 6L, 6R connected with first and second cylinder blocks. 7L, 7R, the first and second case halves 6L, 6R are provided integrally with first and second journal supporting walls 13Lm, 13Rm for supporting a middle journal 3m of the crank shaft 1, the first and second journal supporting walls 13Lm, 13Rm fronting on cylinder bores 10Lr, 10Rf of the first and second cylinder blocks 7L, 7R, and the first and second journal supporting walls are coupled by a plurality of first bolts 19L inserted from the side of the cylinder bore 10Lr of the first cylinder block 7L and disposed on both sides of and in proximity to the middle journal 3m.

Claims

A crank shaft supporting structure for a horizontal opposed type internal combustion engine comprising a crank shaft (1), pluralities of first and second pistons (4Lf, 4Lr; 4Rf, 4Rr) connected to said crank shaft (1), disposed opposite to each other with the crank shaft (1) therebetween and arranged with an offset from each other along the axial direction of said crank shaft (1), a crankcase (6) for containing and supporting said crank shaft (1), and first and second cylinder blocks (7L, 7R) connected to and disposed on both sides of said crankcase (6) and having cylinder bores (10Lf, 10Lr; 10Rf, 10Rr) for slidable fitting therein of said first and second pistons (4Lf, 4Lr; 4Rf, 4Rr), said crankcase (6) being split along a plane (P) containing the axis line (A) of said crank shaft (1) into first and second case halves (6L, 6R) connected respectively with said first and second cylinder blocks (7L, 7R), wherein
said first and second case halves (6L, 6R) are provided integrally with first and second journal supporting walls (13Lm, 13Rm) for rotatably supporting a middle journal (3m) of said crank shaft (1) therebetween, said first and second journal supporting walls (13Lm, 13Rm) fronting on said cylinder bores (10Lr, 10Rf) of said first and second cylinder blocks (7L, 7R), and said first and second journal supporting walls (13Lm, 13Rm) are connected by a plurality of first bolts (19L) inserted from the side of said cylinder bore (10Lr) of said first cylinder block (7L) and disposed on both sides of and in proximity to said middle journal (3m).
A crank shaft supporting structure for horizontal opposed type internal combustion engine as set forth in claim 1, wherein
said first and second journal supporting walls (13Lm, 13Rm) are connected by a plurality of second bolts (19R) inserted from the side of the cylinder bore (10Rf) of said second cylinder block (7R) and disposed on both sides of and in proximity to said middle journal (3m).