speed converter

Abstract

Speed converter (7) comprising a speed converter housing (8) having a housing-side fastening portion (23) formed on one of its outer peripheral surfaces and fastened to an internal combustion engine (6), wherein the speed converter housing (8) is connected to a vehicle body (2A, 2B, 3) via a mounting device (12), so that the speed converter housing (8) is elastically supported by the vehicle body (2A, 2B, 3) together with the internal combustion engine (6), wherein the speed converter housing (8) comprises a drive shaft bearing projection (24), a first fastening means (23I, 46I), a second fastening means (23J, 46J), a third fastening means (23A, 46A), a fourth fastening means (23H, 46H) and a support projection (60), wherein the drive shaft bearing projection (24) is arranged on a rear side of the housing-side fastening portion (23) and supports a drive shaft (9A, 9B) through which power generated by the internal combustion engine (6) is transmitted to a drive wheel (20A, 20B), wherein the first fastening means (23I, 46I) and the second fastening means (23J, 46J) are arranged at a distance from each other in the circumferential direction of the housing-side fastening section (23) and are connected to the internal combustion engine (6), wherein the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H) are arranged in the circumferential direction of the housing-side fastening portion (23) at a distance from each other above the first fastening means (23I, 46I) and the second fastening means (23J, 46J), wherein the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H) are connected to the internal combustion engine (6), and wherein the support projection (60) comprises a first projection (25) and a second projection (26) to which the support device (12) is attached, the second projection (26) being located on a front or a rear side of the first projection (25), wherein on the speed converter housing (8), the first projection (25) is located on a first imaginary line (50) that passes through the first (23I, 46I) and the second fastening means (23J, 46J), and the drive shaft bearing projection (24) is located between the first imaginary line (50) and a second imaginary line (51) that passes through the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H), and is arranged on a third imaginary line (52) that passes through the first projection (25) and the fourth fastening means (23H, 46H), wherein the second projection (26) is formed above the first projection (25) and surrounds the center of the drive shaft bearing projection (24) together with the fourth fastening means (23H, 46H) and the first projection (25), wherein the first projection (25) and the second projection (26) are formed on the speed converter housing (8) such that a fourth imaginary line (53) leading through the first projection (25) and the second projection (26) is inclined such that it crosses the third imaginary line (52), and wherein the second projection (26) is connected to the drive shaft bearing projection (24).

Description

BACKGROUND OF THE INVENTION1 Technical field

[0001] The present invention generally relates to a vehicle-mounted speed converter. 2 State of the art

[0002] JP 2005-90 965 A discloses a drive train consisting of an engine and a transmission, which is elastically supported in a vehicle body by means of a vibration-isolating mounting device. The vibration-isolating mounting device elastically supports the transmission on the vehicle body by means of a torsion bar.

[0003] The above-mentioned gearbox is unlikely to improve the rigidity of a gearbox housing against a reaction force transmitted to the gearbox via the torsion bar during a mechanical vibration of the driveline.

[0004] It is therefore impossible to securely attach the drive train to the vehicle body using the torsion bar, which leads to the risk of effectively reducing the vibration transmitted from the drive train to the vehicle body.

[0005] From JP 2009-236 189 A a fastening structure for a transmission is known, consisting of a first transmission housing which accommodates a fluid transmission mechanism or a clutch mechanism which is connected to one end side of a crankshaft in an engine body, a second transmission housing for accommodating a transmission mechanism and a mounting bracket mounting structure for a transmission in which a mounting bracket is fastened to the first transmission housing. SUMMARY OF THE INVENTION

[0006] The invention was made in view of the foregoing problems. The object of the invention is to provide a speed converter equipped with a speed converter housing having an increased degree of rigidity around a support boss to minimize mechanical vibrations transmitted to a vehicle body.

[0007] According to one aspect of the invention, a speed converter is provided, including a speed converter housing having a housing-side attachment portion formed on one of its outer peripheral surfaces and attached to an internal combustion engine. The speed converter housing is connected to a vehicle body via a bracket device, so that the speed converter housing, together with the internal combustion engine, is elastically supported by the vehicle body. The speed converter housing includes a drive shaft support boss, a first fastening means, a second fastening means, a third fastening means, a fourth fastening means, and a support boss. The drive shaft support boss is disposed on a rear side of the housing-side attachment portion and supports a drive shaft through which power generated by the internal combustion engine is transmitted to a drive wheel.The first fastening means and the second fastening means are arranged at a distance from each other in the circumferential direction of the housing-side fastening portion and are connected to the internal combustion engine. The third fastening means and the fourth fastening means are arranged above the first fastening means and the second fastening means, at a distance from each other in the circumferential direction of the housing-side fastening portion. The third fastening means and the fourth fastening means are connected to the internal combustion engine. The mounting projection includes a first projection and a second projection to which the mounting device is attached. The second projection is located on a front or rear side of the first projection.On the speed converter housing, the first projection is located on a first imaginary line passing through the first and second fastening means, and the drive shaft bearing projection is located between the first imaginary line and a second imaginary line passing through the third fastening means and the fourth fastening means, and on a third imaginary line passing through the first projection and the fourth fastening means. The second projection is formed above the first projection and surrounds the center of the drive shaft bearing projection together with the fourth fastening means and the first projection. The first projection and the second projection are formed on the speed converter housing such that a fourth imaginary line passing through the first projection and the second projection is inclined to cross the third imaginary line, the second projection being connected to the drive shaft bearing projection.

[0008] In the preferred embodiment, the internal combustion engine includes a crankshaft. When viewing the speed converter in an axial direction of the drive shaft, the drive shaft bearing boss is formed on the speed converter housing such that its center is located on a side of the third imaginary line opposite the rotational center of the crankshaft.

[0009] In the foregoing preferred embodiment, the fourth fastening means and the fourth projection are connected to the drive shaft bearing projection.

[0010] In the foregoing preferred embodiment, the internal combustion engine includes a cylinder block in which the crankshaft is rotatably supported. The speed converter housing includes an upper fastener and a rib. The upper fastener is located above the first fastener or the second fastener arranged in the housing-side fastening portion and is fastened to the cylinder block. The rib connects the upper fastener and the fourth fastener along the third imaginary line. The rib extends to an outer peripheral edge of the speed converter housing.

[0011] In the foregoing preferred embodiment, the second projection is formed above the first projection and surrounds the center of the drive shaft support projection together with the fourth fastener and the first projection. The first projection and the second projection are formed on the speed converter housing such that a fourth imaginary line passing through the first projection and the second projection is inclined to cross the third imaginary line. The second projection is connected to the drive shaft support projection.

[0012] In the foregoing preferred embodiment, the speed converter housing has an outer peripheral edge connected to the second fastening means via the rib. The second projection is formed on the outer peripheral edge.

[0013] In the foregoing preferred embodiment, the rib is provided as a first rib. The speed converter housing includes a second rib and a third rib. The second rib connects the first fastening means and the drive shaft bearing projection and extends via the drive shaft bearing projection to the fourth fastening means. The third rib connects the first fastening means to the first projection. The speed converter housing has an annular portion formed by the second fastening means, the second rib, the fourth fastening means, the third rib, the first projection, and the drive shaft bearing projection.

[0014] The third rib connects a lower end of the first projection to the fastener. A fourth rib is formed on the speed converter housing, which connects an upper end of the first projection to the first fastener between the second rib and the third rib. EFFECTS OF THE INVENTION

[0015] The invention allows an increase in the stiffness or rigidity of a speed converter in the vicinity of a support projection in order to minimize mechanical vibrations transmitted to a vehicle body. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a front portion of a vehicle equipped with a speed converter according to an embodiment of the invention. Fig. 2 is a rear view illustrating a drive unit equipped with a speed converter according to an embodiment of the invention. Fig. 3 is a side view illustrating an engine equipped with a speed converter according to an embodiment of the invention, viewed from the side of the speed converter, with the speed converter removed. Fig. 4 is a side view illustrating a right case of a speed converter according to an embodiment of the invention, viewed from the side of an engine with the engine removed. Fig. 5 is a side view illustrating a right housing of a speed converter according to an embodiment of the invention, viewed from an engine, with the engine, a left housing, and a rear bracket removed. EMBODIMENT OF THE INVENTION

[0016] A speed converter according to an embodiment of the invention includes a speed converter housing having a housing-side attachment portion formed on one of its outer peripheral surfaces and attached to an internal combustion engine. The speed converter housing is connected to a vehicle body via a bracket device, so that the speed converter, together with the internal combustion engine, is elastically supported by the vehicle body. The speed converter housing includes a drive shaft support boss, a first fastening means, a second fastening means, a third fastening means, a fourth fastening means, and a support boss. The drive shaft support boss is disposed on a front or rear side of the housing-side attachment portion and supports a drive shaft through which power generated by the internal combustion engine is transmitted to a drive wheel.The first fastening means and the second fastening means are arranged at a distance from each other in the circumferential direction of the housing-side fastening portion and are connected to the internal combustion engine. The third fastening means and the fourth fastening means are arranged above the first fastening means and the second fastening means, at a distance from each other in the circumferential direction of the housing-side fastening portion. The third fastening means and the fourth fastening means are connected to the internal combustion engine. The mounting projection includes a first projection and a second projection to which the mounting device is attached. The second projection is located on a front or rear side of the first projection.On the speed converter housing, the first projection is located on a first imaginary line passing through the first and second fasteners, and the drive shaft support projection is located between the first imaginary line and a second imaginary line passing through the third fastener and the fourth fastener, and on a third imaginary line passing through the first projection and the fourth fastener. These arrangements increase the rigidity of the speed converter housing in the vicinity of the support projection to minimize mechanical vibrations transmitted to the vehicle body. FIRST EMBODIMENT

[0017] In the following, an embodiment of a speed converter according to the invention will be described with reference to the drawings.

[0018] The Fig. 1 to 5 are views illustrating the speed converter in the embodiment of the invention. Fig. 1 to 5, the directions “forward”, “backward”, “right”, “left”, “up” and “down” are relative directions, seen from the point of view of a driver entering the vehicle.

[0019] First, the structure is described.

[0020] In the Fig. 1, the vehicle 1 is equipped with the side members 2A and 2B and the suspension frame 3, which constitute a vehicle body of the invention. The side members 2A and 2B are arranged opposite each other on both sides of the vehicle 1 in the vehicle width direction (hereinafter referred to as the vehicle width direction) and extend in the longitudinal direction of the vehicle 1. The suspension frame 3 extends in the vehicle width direction and is connected to the side members 2A and 2B.

[0021] A space enclosed by the side members 2A and 2B and the suspension frame 3 forms the engine compartment 4. The drive train 5 is arranged in the engine compartment 4. The drive train 5 includes the engine 6 and the transmission 7, which serves as a speed converter. In this embodiment, the engine 6 is an internal combustion engine of the invention.

[0022] As in the Fig. 2 and Fig. 3, the engine 6 comprises the cylinder block 41, the cylinder head 42 arranged on the cylinder block 41 and the oil pan 43 arranged below the cylinder block 41. Oil, not shown, is stored in the oil pan 43.

[0023] In the cylinder block 41, a piston (not shown) and the crankshaft 41A (see Fig. 3), which serves to convert the reciprocating motion of the piston into a rotary motion. Intake and exhaust camshafts (not shown) as well as intake and exhaust valves (not shown) are installed in the cylinder head 42.

[0024] The gear 7 (ie the speed converter) is, as in Fig. 1, is provided with the transmission case 8 (i.e., a speed converter case) in which transmission mechanisms such as a transmission gear set, an input shaft, and a countershaft (not shown) are arranged.

[0025] The transmission 7 is equipped with a differential gear (not shown) connected to the left and right drive wheels 20A and 20B via the left and right drive shafts 9A and 9B. The transmission 7 changes the speed of the engine 6 through the transmission mechanisms and transmits it from the differential gear to the left and right drive wheels 20A and 20B via the left and right drive shafts 9A and 9B.

[0026] One of the ends of the engine 6 in the vehicle width direction is elastically connected to the side member 2A via the right front-rear bracket 10. One of the ends of the transmission 7 in the vehicle width direction is elastically connected to the side member 2B via the left front-rear bracket 11. In other words, opposite ends of the powertrain 5 in the vehicle width direction are elastically supported on the side members 2A and 2B via the right front-rear bracket 10 and the left front-rear bracket 11.

[0027] Upper portions of the opposite ends of the powertrain 5 in the vehicle width direction are suspended from the right front-rear bracket 10 and the left front-rear bracket 11, thereby fixing the powertrain 5 to the side members 2A and 2B. The suspension system in this embodiment is configured as a pendulum suspension system.

[0028] The pendulum suspension system allows the drive train 5 to oscillate in the longitudinal direction of the vehicle 1. To prevent such movement, the transmission 7 and the suspension frame 3 are connected to each other via the rear bracket 12 in the longitudinal direction of the vehicle 1.

[0029] The rear bracket 12 is, as shown in Fig. 4, is equipped with the torsion bar 13, which is connected at its rear end to the suspension frame 3 and at its front end to the rear support bracket 14 by means of the bolt 15. The rear support bracket 14 is fixed to the transmission housing 8 by means of a plurality of bolts 16A, 16B, and 16C. In this embodiment, the rear bracket 12 forms a support device.

[0030] As in Fig. As shown in Figure 3, the engine 6 has an annular mounting portion 17 formed on one of its side surfaces. The mounting portion 17 consists of the mounting portion 44 formed on the cylinder block 41 and the mounting portion 45 formed on the oil pan 43.

[0031] As in Fig. 1 and Fig. 2, the transmission housing 8 comprises the left housing 21 and the right housing 22. The left housing 21 is elastically supported by the left front-rear bracket 11 on the side member 2B (see Fig. 1).

[0032] As in Fig. 3 and Fig. 4, the fixing portion 23 is formed on an outer peripheral surface of the right housing 22. As described below (see Fig. 3) The fastening portion 23 is connected to the fastening portion 17 of the motor 6 by bolts, thereby connecting the transmission 7 to the motor 6. The fastening portion 23 of this embodiment forms a housing-side fastening portion of the invention.

[0033] The drive shaft support projection 24 is formed on the right housing 22. The drive shaft support projection 24 is arranged on the rear side of the mounting portion 23. The drive shaft 9A is elastically supported by the drive shaft support projection 24 via a bearing (not shown).

[0034] The right case 22 includes the transmission mechanism housing 22A, in which the transmission mechanisms are arranged, and the differential case 22B, in which the differential gear is arranged. The drive shaft support projection 24 is formed on a wall surface of the differential case 22B.

[0035] As in Fig. 3, the cylinder axis 6A in the engine 6 extends perpendicular to the rotational axis O1 of the crankshaft 41A. The engine 6 is inclined at a small angle θ formed by the cylinder axis 6A with the vertical axis 55, so that a space for installing the engine 6 in the vehicle 1 is small.

[0036] The engine 6 is tilted at a small angle θ, so that the differential case 22B protrudes rearward from the engine 6. In other words, the differential case 22B protrudes rearward from the engine 6. The differential case 22B is located below the transmission mechanism housing 22A.

[0037] As in Fig. 4 and Fig. 5, the fastening portion 23 includes a plurality of bolt through-hole portions 23A to 23F, bolt hole portions 23G and 23H having internal threads formed on their inner peripheries, and bolt through-hole portions 23I and 23J. The bolt through-hole portions 23A to 23F, the bolt hole portions 23G and 23H, and the bolt through-hole portions 23I and 23J are arranged at intervals in a circumferential direction of the fastening portion 23.

[0038] As in Fig. 3, the attachment portion 44 of the cylinder block 41 has a plurality of bolt through-hole portions 44A to 44H arranged at intervals in its circumferential direction. The attachment portion 45 of the oil pan 43 has a plurality of bolt through-hole portions 45I and 45J arranged at intervals in its circumferential direction.

[0039] The motor 6 and the right housing 22 are fastened together by, as shown in Fig. 3, the bolts 46A to 46F are inserted into the bolt through-hole portions 23A to 23F and into the bolt through-hole portions 44A to 44F, and then nuts (not shown) are screwed onto the bolts 46A and 46F to connect the fastening portions 23 and 44.

[0040] The motor 6 and the right housing 22 are also attached to each other by, as in Fig. 3, the bolts 46G and 46H are fastened into the bolt hole portions 23G and 23H through the bolt through hole portions 44G and 44H to connect the fastening portions 23 and 44 to each other.

[0041] Furthermore, the motor 6 and the right housing 22 are also fixed to each other by, as shown in Fig. 3, the bolts 46I and 46J are inserted into the bolt through holes 23I and 23J and the bolt through holes 45I and 45J, and then nuts (not shown) are screwed onto the bolts 46I and 46J to connect the fastening portions 23 and 45 together.

[0042] In this way, the right housing 22 is fixed to the engine 6 by connecting the fixing portion 23 to the fixing portions 44 and 45 by means of the bolts 46A to 46J.

[0043] When the fixing portion 23 is connected to the fixing portions 44 and 45, in the gear 7 of this embodiment, any combination of through holes having a reference numeral with the same letter or any combination of bolt through hole portions having a reference numeral with the same letter is positioned.

[0044] The bolt 46A and the bolt through-hole portion 23A of this embodiment constitute a third fastening means of the invention. The bolt 46H and the bolt through-hole portion 23H of this embodiment constitute a fourth fastening means of the invention. The bolt 46I and the through-hole portion 23I of this embodiment constitute a first fastening means of the invention. The bolt 46J and the bolt through-hole portion 23J of this embodiment constitute a second fastening means of the invention. The bolt through-hole portion 23A, the bolt through-hole portion 23H, the bolt through-hole portion 23J, and the bolt through-hole portion 23I are part of a surrounding portion of the fastening portion 23.

[0045] The bolt through hole portion 23A and the bolt hole portion 23H are, as shown in Fig. 4 and Fig. 5, formed in the right housing 22 and arranged above the bolt through-hole portion 23I and the bolt through-hole portion 23J substantially at the same height in the vertical direction of the vehicle 1.

[0046] The bolt through-hole portion 23I and the bolt through-hole portion 23J are formed in the right housing 22 and are located substantially at the same height in the vertical direction of the vehicle 1.

[0047] On the right housing 22, as shown in Fig. 5, the front projection 25 and the rear projection 26 are formed, which is located on the rear side of the front projection 25. Two bolt hole portions 25A and 25B are formed in the front projection 25, and threads are formed in the inner peripheral surfaces thereof. A single bolt hole portion 26A is formed in the rear projection 26, and a thread is formed in the inner peripheral surface thereof.

[0048] The rear support bracket 14 is connected to a lower portion of the differential case 22B by fastening the bolts 16A, 16B and 16C into the bolt hole portions 25A, 25B and 26A.

[0049] The front projection 25 and the rear projection 26 of this embodiment form a retaining projection of the invention. The front projection 25 also forms a first projection of the invention. The rear projection 26 also forms a second projection of the invention.

[0050] The front projection 25 is formed on the first imaginary line 50 passing through the bolt through-hole portion 23I and the bolt through-hole portion 23J.

[0051] The drive shaft support projection 24 is arranged between the first imaginary line 50 and the second imaginary line 51 passing through the bolt through-hole portion 23A and the bolt hole portion 23H and is located on or intersecting the third imaginary line 52 passing through the first projection 25 and the bolt hole portion 23H.

[0052] In this embodiment, the first imaginary line 50 crosses near a lower portion of the oil pan 43. The second imaginary line 51 crosses near a lower portion of the cylinder block 41. The drive shaft support boss 24 is thus arranged between the lower portion of the cylinder block 41 and the lower portion of the oil pan 43 in the vertical direction of the vehicle 1.

[0053] When the right housing 22 is viewed in an axial direction of the drive shafts 9A and 9B, ie in the vehicle width direction of the vehicle 1 in Fig. 5, the drive shaft bearing projection 24 is formed on the differential case 22B such that its center O2 is located on the side of the third imaginary line 52 opposite the central rotational axis O1 of the crankshaft 41A.

[0054] The bolt hole portion 23H is located above the drive shaft bearing boss 24 and is connected to the drive shaft bearing boss 24. The front boss 25 is located below the drive shaft bearing boss 24 and is connected to the drive shaft bearing boss 24. Thus, the bolt hole portion 23H is connected to the front boss 25 via the drive shaft bearing boss 24.

[0055] The bolt hole portion 23G is formed in the fastening portion 23 and is located above the bolt hole portion 23H. The bolt hole portion 23G of this embodiment forms an upper fastening means of the invention.

[0056] The right housing 22 has the rib 27 connecting the bolt hole portion 23G to the bolt hole portion 23H along the third imaginary line 52.

[0057] The rear projection 26 is formed above the front projection 25 in the vertical direction of the vehicle 1 and surrounds the center O2 of the drive shaft support projection 24 together with the bolt hole portion 23H and the front projection 25.

[0058] As in Fig. 5, the fourth imaginary line 53 passing through the front projection 25 and the rear projection 26 is inclined relative to the third imaginary line 52. The front projection 25 is located closer to the front and bottom of the vehicle 1 than the rear projection 26 and extends forward and downward in the vehicle 1.

[0059] The rear projection 26 is connected to the drive shaft support projection 24. The front projection 25 and the rear projection 26 are spaced apart from each other in the circumferential direction of the drive shaft support projection 24.

[0060] The right housing 22 has the outer peripheral edge 22C. The outer peripheral edge 22C is connected at one end to the rear projection 26 and at the other end to the bolt hole portion 23G in the circumferential direction of the outer peripheral edge 22C.

[0061] In this embodiment, the outer peripheral edge 22C is connected to the bolt hole portion 23H via the rib 27. The rear portion 26 is formed on the outer peripheral edge 22C. The drive shaft support projection 24 is connected to the outer peripheral edge 22C via the rear projection 26.

[0062] Ribs 28 and 29 are formed on the right housing 2. The rib 28 connects the bolt through-hole portion 23I and the drive shaft support boss 24, so that it is connected to the bolt hole portion 23H via the drive shaft support boss 24. The rib 29 connects the bolt through-hole portion 23I and a lower end of the front boss 25.

[0063] Rib 27 of this embodiment forms a first rib of the invention. Rib 28 of this embodiment forms a second rib of the invention. Rib 29 of this embodiment forms a third rib of the invention.

[0064] The annular portion 30 is formed on the right housing 22. The annular portion 30 is formed annularly by the bolt hole portion 23H, the rib 28, the bolt through-hole portion 23I, the rib 29, the front projection 25, and the drive shaft support projection 24.

[0065] The rib 31 is formed on the right housing 22. The rib 31 connects an upper end of the front projection 25 and the bolt through-hole portion 23I between the ribs 28 and 29. The rib 31 of this embodiment constitutes the fourth rib of the invention.

[0066] The operation is described below. When the driveline 5 pivots back and forth in the vehicle 1, the rear mount 12 serves to control such movement of the driveline 5 and reduce the physical vibrations transmitted from the driveline 5 to the suspension frame 3.

[0067] In the transmission 7, the differential case 22B protrudes rearward from the engine 6 in the right housing 22. The rear support bracket 14 is attached to the differential case 22B. The rear support bracket 14 is connected to the suspension frame 3 via the torsion bar 13.

[0068] As in Fig. 4, the forward and rearward movement of the drive train 5 thus creates the load F which is exerted by the drive train 5 via the rear support beam 14 and the torsion bar 13 on the suspension frame 3, so that the reaction force Fp is exerted by the suspension frame 3 via the torsion bar 13 on the rear support beam 14.

[0069] The reaction force Fp is applied as separate loads F1 and F2 to the front projection 25 and the rear projection 26. The loads F1 and F2 develop offset moments M2 and M2 acting on the front projection 25 and the rear projection 26.

[0070] In this embodiment, the transmission 7 includes the right housing 22, which is provided with the drive shaft support boss 24 and the bolt through-hole portions 23I and 23J. The drive shaft support boss 24 is formed on the rear side of the mounting portion 23 and supports the drive shafts 9A and 9B, through which power or torque generated by the engine 6 is transmitted to the drive wheels 20A and 20B. The bolt through-hole portions 23I and 23J are spaced apart from each other in the circumferential direction of the mounting portion 23 and connected to the engine 6.

[0071] The right housing 22 is provided with the bolt through-hole portion 23A, the bolt hole portion 23H, and the support projection 60. The bolt through-hole portion 23A and the bolt hole portion 23H are arranged above the bolt through-hole portions 23I and 23J, spaced apart from each other in the circumferential direction of the mounting portion 23, and are connected to the engine 6. The support projection 60 is provided with the front projection 25 and the rear projection 26, to which the rear support bracket 14 is attached.

[0072] On the right housing 22, the front protrusion 25 is arranged on the first imaginary line 50 passing through the bolt through-hole portion 23I and the bolt through-hole portion 23J. On the right housing 22, the drive shaft support protrusion 24 is also arranged on the third imaginary line 52 passing through the front protrusion 25 and the bolt through-hole portion 23H, between the first imaginary line 50 and the second imaginary line 51. The second imaginary line 51 passes through the bolt through-hole portion 23A and the bolt through-hole portion 23H.

[0073] By the foregoing arrangements, the bolt hole portion 23H, the drive shaft support boss 24, the front boss 25, and the rear boss 26, which have high rigidity, are located in a range between the first imaginary line 50 and the second imaginary line 51, in other words, between the lower portion of the cylinder block 41 and the lower portion of the oil pan 43 in the vertical direction of the vehicle 1.

[0074] The foregoing arrangements allow an increase in the rigidity of the differential case 22B in the vicinity of the front projection 25 and rear projection 26 into which the loads F1 and F2 are introduced, thereby minimizing the vibrations of the right case 22 caused by the offset moments M1 and M2.

[0075] The foregoing arrangements also ensure the stability of securing the drive train 5 to the suspension frame 3 by means of the rear bracket 12 and minimize the vibrations transmitted from the drive train 5 to the suspension frame 3.

[0076] In this embodiment, the transmission 7 has the right housing 22 on which the drive shaft support projection 24 is formed such that the center O2 on the third imaginary line 52 is located at the end opposite to the rotation center O1 of the crankshaft 41A when the right housing 22 is viewed in the axial direction of the drive shafts 9A and 9B.

[0077] The foregoing arrangement allows an increase in the rigidity of the right case 22 in the vicinity of the front projection 25 and rear projection 26, thereby minimizing the vibrations of the right case 22 caused by the offset moments M1 and M2, even if the differential case 22B protrudes far rearward from the engine 6.

[0078] In this embodiment, the bolt hole portion 23H and the front protrusion 25 on the transmission 7 are connected to the drive shaft support protrusion 24, allowing the bolt hole portion 23H, the drive shaft support protrusion 24, and the front protrusion 25 to be arranged in a small area. This further improves the rigidity of the right housing 22 in the vicinity of the front protrusion 25.

[0079] In this embodiment, the right housing 22 in the transmission 7 is provided with the bolt hole portion 23G and the rib 27. The bolt hole portion 23G is formed in the mounting portion 23 above the bolt hole portion 23H and is fixed to the cylinder block 41. The rib 27 connects the bolt hole portion 23G and the bolt hole portion 23H substantially along the third imaginary line 52. The rib 27 extends to the outer peripheral edge 22C of the right housing 22.

[0080] With the foregoing arrangements, the front projection 25, the drive shaft support projection 24, the bolt hole portion 23H, and the rib 27 are substantially aligned in the vertical direction of the vehicle 1, thereby improving the rigidity of the differential case 22B projecting rearward from the engine 6. This further minimizes the vibrations of the right case 22 caused by the offset moments M1 and M2.

[0081] In this embodiment, the transmission 7 has the rear projection 26 disposed above the upper portion of the front projection 25 and surrounding the center O2 of the drive shaft support projection 24 together with the bolt hole portion 23H and the front projection 25.

[0082] On the right housing 22, the front projection 25 and the rear projection 26 are formed, which are aligned such that the fourth imaginary line 53 passes through the front projection 25 and the rear projection 26 and is inclined such that it crosses the third imaginary line 52. The rear projection 26 is connected to the drive shaft bearing projection 24.

[0083] As in Fig. 4, due to the foregoing arrangements, the load F1 introduced into the front projection 25 and the load F2 introduced into the rear projection 26 are aligned as loads f1 and f2 in the circumferential direction of the drive shaft support projection 24.

[0084] The loads f1 and f2 are combined into a load f3 through the bolt hole portion 23H and the rib 27, which have high rigidity, and released into the fastening portion 23.

[0085] This prevents the accumulation of loads F1 and F2 in a certain area of the drive shaft bearing boss 24, thereby effectively minimizing the vibrations of the right housing 22 generated by the offset moments M1 and M2.

[0086] The transmission 7 is equipped with the right case 22, the outer peripheral edge 22C of which is connected to the bolt hole portion 23H via the rib 27. The rear projection 26 is formed on the outer peripheral edge 22C.

[0087] By the foregoing arrangements, the annular formation of the drive shaft support projection 24 is facilitated, and the annular portion 32 is formed by the outer peripheral edge 22C, the rear projection 26, the drive shaft support projection 24, the bolt hole portion 23H, the rib 27 and the bolt hole portion 23G of the right case 22 above the front projection 25, which extend continuously.

[0088] The foregoing arrangements further increase the rigidity of the differential case 22B, thereby improving the reduction of the vibrations of the right case 22 caused by the offset moments M1 and M2.

[0089] The transmission 7 includes the right housing 22, which also connects the pin through-hole portion 23I and the drive shaft support projection 24 to form the ribs 28 and 29. The rib 28 is connected to the pin through-hole portion 23H via the drive shaft support projection 24. The rib 29 connects the pin through-hole portion 23I to the front projection 25.

[0090] In addition, the right housing 22 also includes the annular portion 30 formed by the bolt hole portion 23H, the rib 28, the bolt through hole portion 23I, the rib 29, the front projection 25, and the drive shaft bearing projection 24.

[0091] The foregoing arrangements make it easy to achieve the annular configuration of the drive shaft bearing boss 24 and the annular portion 32, and the annular portion 30 is disposed on the opposite side of the drive shaft bearing boss 24 from the annular portion 32.

[0092] The rigidity of the differential case 22B is thus further increased. Furthermore, the load F2 introduced into the front projection 25 is separated into the load f1, the load f4, and the load f5. The load f1 is transmitted from the front projection 25 to the rib 27 via the drive shaft support projection 24. The load f4 is transmitted from the front projection 25 to the rib 28. The load f5 is transmitted from the front projection 25 to the rib 29.

[0093] This prevents the accumulation of loads F1 and F2 in certain areas of the drive shaft bearing boss 24, thereby minimizing the vibrations of the right housing 22 generated by the offset moments M1 and M2.

[0094] In this embodiment, the gear 7 is formed such that the rib 29 connects the lower end of the front projection 25 and the bolt through-hole portion 23I. Also formed on the right housing 22 is the rib 31 connecting the upper end of the front projection 25 to the bolt through-hole portion 23I between the ribs 28 and 29.

[0095] Thereby, the load F1 introduced into the front projection 25 is converted into the load f6, which is transmitted to the rib 31 in addition to the loads f7, f4 and f5, thereby preventing the accumulation of the loads F1 and F2 in certain areas of the drive shaft bearing projection 24, so that the suppression of the vibrations of the right housing 22 generated by the offset moments M1 and M2 is improved.

[0096] In this embodiment, in the transmission 7, the front projection 25 is designed as a first projection and the rear projection 26 is designed as a second projection, but the second projection can also be designed as a front projection 25 and the first projection as a rear projection 26.

Claims

[1] Speed converter (7) comprising a speed converter housing (8) having a housing-side fastening portion (23) formed on one of its outer peripheral surfaces and fastened to an internal combustion engine (6), wherein the speed converter housing (8) is connected to a vehicle body (2A, 2B, 3) via a mounting device (12), so that the speed converter housing (8) is elastically supported by the vehicle body (2A, 2B, 3) together with the internal combustion engine (6), wherein the speed converter housing (8) comprises a drive shaft bearing projection (24), a first fastening means (23I, 46I), a second fastening means (23J, 46J), a third fastening means (23A, 46A), a fourth fastening means (23H, 46H) and a support projection (60), wherein the drive shaft bearing projection (24) is arranged on a rear side of the housing-side fastening portion (23) and supports a drive shaft (9A, 9B) through which power generated by the internal combustion engine (6) is transmitted to a drive wheel (20A, 20B), wherein the first fastening means (23I, 46I) and the second fastening means (23J, 46J) are arranged at a distance from each other in the circumferential direction of the housing-side fastening section (23) and are connected to the internal combustion engine (6), wherein the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H) are arranged in the circumferential direction of the housing-side fastening portion (23) at a distance from each other above the first fastening means (23I, 46I) and the second fastening means (23J, 46J), wherein the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H) are connected to the internal combustion engine (6), and wherein the support projection (60) comprises a first projection (25) and a second projection (26) to which the support device (12) is attached, the second projection (26) being located on a front or a rear side of the first projection (25), wherein on the speed converter housing (8), the first projection (25) is located on a first imaginary line (50) that passes through the first (23I, 46I) and the second fastening means (23J, 46J), and the drive shaft bearing projection (24) is located between the first imaginary line (50) and a second imaginary line (51) that passes through the third fastening means (23A, 46A) and the fourth fastening means (23H, 46H), and is arranged on a third imaginary line (52) that passes through the first projection (25) and the fourth fastening means (23H, 46H), wherein the second projection (26) is formed above the first projection (25) and surrounds the center of the drive shaft bearing projection (24) together with the fourth fastening means (23H, 46H) and the first projection (25), wherein the first projection (25) and the second projection (26) are formed on the speed converter housing (8) such that a fourth imaginary line (53) leading through the first projection (25) and the second projection (26) is inclined such that it crosses the third imaginary line (52), and wherein the second projection (26) is connected to the drive shaft bearing projection (24). [2] The speed converter (7) according to claim 1, wherein the internal combustion engine (6) has a crankshaft (41A), and wherein, when the speed converter housing (8) is viewed in an axial direction of the drive shaft (9A, 9B), the drive shaft support projection (24) is formed on the speed converter housing (8) such that its center (O2) is located on a side of the third imaginary line (52) opposite a rotation center (O1) of the crankshaft (41A). [3] The speed converter (7) according to claim 1 or 2, wherein the fourth fastening means (23H, 46H) and the first projection (25) are connected to the drive shaft bearing projection (24). [4] The speed converter (7) according to claim 2, wherein the internal combustion engine (6) has a cylinder block (41) in which the crankshaft (41A) is rotatably supported, the speed converter housing (8) comprising an upper fastening means (23G) and a rib (27), the upper fastening means (23G) being located above the first fastening means (23I, 46I) or the second fastening means (23J, 46J) arranged in the housing-side fastening portion (23) and being fastened to the cylinder block (41), the rib (27) connecting the upper fastening means (23G) and the fourth fastening means (23H, 46H) along the third imaginary line (52), and the rib (27) leading to an outer peripheral edge (22C) of the speed converter housing (8). [5] The speed converter (7) according to claim 1 or 2, wherein the speed converter housing (8) has an outer peripheral edge (22C) connected to the second fastening means (23J, 46J) via the rib (27), and wherein the second projection (26) is formed on the outer peripheral edge (22C). [6] Speed converter (7) according to claim 4, wherein the rib (27) is provided as a first rib, wherein the speed converter housing (8) comprises a second rib (28) and a third rib (29), wherein the second rib (28) connects the first fastening means (23I, 46I) and the drive shaft bearing projection (24) and leads via the drive shaft bearing projection (24) to the fourth fastening means (23H, 46H), wherein the third rib (29) connects the first fastening means (23I, 46I) to the first projection (25), and wherein the speed converter housing (8) has an annular portion (30) which is formed by the second fastening means (23J, 46J), the second rib (28), the fourth fastening means (23H, 46H), the third rib (29), the first projection (25) and the drive shaft bearing projection (24) is formed. [7] Speed converter (7) according to claim 6, wherein the third rib (29) connects a lower end of the first projection (25) to the first fastening means (23I, 46I), and wherein a fourth rib (31) is formed on the speed converter housing (8) and connects an upper end of the first projection (25) to the first fastening means (23I, 46I) between the second rib (28) and the third rib (29).

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